@article {31851, title = {Split-pane electrochromic window control based on an embedded photometric device with real-time daylighting computing}, journal = {Building and Environment}, volume = {161}, year = {2019}, month = {08/2019}, pages = {106229}, abstract = {

Well-designed electrochromic (EC) glazing control can improve the energy performance of buildings and visual comfort of occupants in highly glazed buildings. This paper designed and demonstrated a compact integrated EC glazing automation system to control tint states of a split-pane EC window according to variations of sky conditions. The control is based on monitoring the luminance distribution of the sky and real-time lighting computation for a building interior, using an embedded photometric device (EPD). It optimizes tint states of EC glazing to offer sufficient daylight provision and temper discomfort glare for occupants, which potentially mitigates excessive solar heat gain. {\textquoteright}In-situ{\textquoteright} experiments were conducted in a full-scale testbed to demonstrate the daylighting performance under various sky conditions. Experimental results showed 83\% of the working time for work-plane illuminance (WPI) and 95\% of the time for daylight glare probability (DGP) were constrained in comfort range (WPI[500, 2000] lux, DGP\ <=\ 0.35) by the automated EC glazing (controlled by EPD) under clear skies; 68\% of the time for WPI and 94\% of the time for DGP in confined range under clear skies with thin clouds; 62\% of the time for WPI and 85\% of the time for DGP in confined range under partly cloudy skies.

}, keywords = {daylighting, electrochromic, Embedded Controller, HDR, windows}, issn = {03601323}, doi = {10.1016/j.buildenv.2019.106229}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0360132319304391}, author = {Yujie Wu and Taoning Wang and Eleanor S. Lee and J{\'e}r{\^o}me H. K{\"a}mpf and Jean-Louis Scartezzini} } @article {31495, title = {Efficient modeling of optically-complex, non-coplanar exterior shading: Validation of matrix algebraic methods}, journal = {Energy and Buildings}, volume = {174}, year = {2018}, month = {09/2018}, pages = {464 - 483}, abstract = {

It has long been established that shading windows with overhangs, fins, and other types of non-coplanar systems (NCS) is one of the most effective ways of controlling solar heat gains in buildings because they intercept solar radiation prior to entry into the building. Designers however often specify non-opaque materials (e.g., louvers, fritted glass, expanded metal mesh) for these systems in order to admit daylight, reduce lighting energy use, and improve indoor environmental quality. Most simulation tools rely on geometric calculations and radiosity methods to model the solar heat gain impacts of NCS and cannot model optically-complex materials or geometries. For daylighting analysis, optically-complex NCS can be modeled using matrix algebraic methods, although time-efficient parametric analysis has not yet been implemented. Determining the best design and/or material for static or operable NCS that minimize cooling, heating, and lighting energy use and peak demand requires an iterative process. This study describes and validates a matrix algebraic method that enables parametric energy analysis of NCS. Such capabilities would be useful not only for design but also for development of prescriptive energy-efficiency standards, rating and labeling systems for commercial products, development of design guidelines, and development of more optimal NCS technologies.

A facade or "F" matrix, which maps the transfer of flux from the NCS to the surface of the window, is introduced and its use is explained. A field study was conducted in a full-scale outdoor testbed to measure the daylight performance of an operable drop-arm awning. Simulated data were compared to measured data in order to validate the models. Results demonstrated model accuracy: simulated workplane illuminance was within 11-13\%, surface luminance was within 16-18\%, and the daylight glare probability was within 6-9\% of measured results. Methods used to achieve accurate results are discussed. Results of the validation of daylighting performance are applicable to solar heat gain performance. Since exterior shading can also significantly reduce peak demand, these models enable stakeholders to more accurately assess HVAC and lighting impacts in support of grid management and resiliency goals.

}, keywords = {bidirectional scattering distribution function (BSDF), daylighting, exterior shading, solar heat gains, validation; building energy simulation tools, windows.}, issn = {03787788}, doi = {10.1016/j.enbuild.2018.06.022}, url = {https://www.sciencedirect.com/science/article/pii/S0378778818302457?via\%3Dihub}, author = {Taoning Wang and Gregory Ward and Eleanor S. Lee} } @inbook {31496, title = {Innovative Glazing Materials}, booktitle = {Handbook of Energy Efficiency in Buildings A Life Cycle Approach}, year = {2018}, month = {11/2018}, publisher = {Butterworth-Heinemann, Elsevier Inc.}, organization = {Butterworth-Heinemann, Elsevier Inc.}, chapter = {6.3}, address = {Cambridge}, abstract = {

Windows have the unique capability of being able to achieve a net zero energy impact by admitting solar gains in the winter to offset thermal losses and admitting daylight to offset electric lighting. If rejection or admission of solar heat gains and daylight are appropriately timed, then heating, cooling and lighting energy use at the perimeter zone can be reduced to net zero energy levels. Nano-scale switchable coatings on glass have been developed to actively modulate solar intensity and spectral transmission. We provide a brief overview of these switchable glazing materials, discuss the desired performance objectives for such materials, and present results from recently completed monitored studies of state-of-the-art switchable windows, particularly with respect to occupant response and market factors. Careful application of state-of-the-art switchable windows and new material science developments on the horizon can deliver the desired net zero energy performance while meeting critical human factors and market related requirements.

}, keywords = {Electrochromics; Thermochromics; Switchable windows; Smart windows; Solar control; Daylighting; Building energy efficiency; Building controls}, isbn = {978-0-12-812817-6}, author = {Eleanor S. Lee} } @article {30007, title = {Daylight performance of a microstructured prismatic window film in deep open plan offices}, journal = {Building and Environment}, volume = {113}, year = {2017}, month = {02/2017}, pages = {280{\textendash}297}, abstract = {

Daylight redirecting systems with vertical windows have the potential to offset lighting energy use in deep perimeter zones. A microstructured prismatic film designed for such use was characterized using goniophotometric measurements and ray tracing simulations. The synthetically-generated bidirectional scattering distribution function (BSDF) data were shown to have good agreement with limited measured data for normal incident angles (0{\textendash}60{\textdegree}). Measured data indicated that the prismatic film was most efficient when vertical angles of incidence were between 18 and 35{\textdegree} and within {\textpm}45{\textdegree} of normal incidence to the plane of the window so maximum energy savings across the full depth of the zone occurred over the equinox to winter solstice period. Annual lighting energy use and visual comfort in a deep open plan office zone were evaluated using the Radiance three-phase method in several climates and for south and east-facing window orientations. Lighting energy savings were 39{\textendash}43\% for a 12\ m (40\ ft) deep south-facing perimeter zone compared to the same zone with no lighting controls. The prismatic film with and without a diffuser controlled glare for views parallel to the window but produced glare for seated viewpoints looking toward the window. At mature market costs, the system was projected to have a simple payback of 2{\textendash}6 years. Technical challenges encountered throughout the evaluation led to improvements in measurement and modeling tools and stressed the importance of having accurate input data for product development.

}, issn = {0360-1323}, doi = {10.1016/j.buildenv.2016.07.019}, author = {Andrew McNeil and Eleanor S. Lee and Jacob C. Jonsson} } @techreport {29657, title = {Demonstration of Energy Efficient Retrofits for Lighting and Daylighting in New York City Office Buildings}, year = {2017}, month = {04/2017}, abstract = {

The U.S. Department of Energy{\textquoteright}s (DOE) Commercial Buildings Integration (CBI) program{\textquoteright}s mission (and that of the New York State Energy Research \& Development Authority (NYSERDA)) is to accelerate the adoption of cost-effective, underutilized building technologies with large energy savings potential. The key question which CBI asks for each high impact technology is: "What can the DOE do to improve the market adoption of this technology?" Answering this relies on an assessment of the most significant barriers, including:

Innovative, automated shading and LED lighting controls were identified as key technologies that have the potential to significantly reduce perimeter zone energy use and peak demand in existing commercial buildings.\  Technological advances in the field of low-cost embedded controls have enabled high-resolution sensing and more optimal control on a per fixture or shade basis. The Lawrence Berkeley National Laboratory (LBNL) partnered with the Building Energy Exchange (BEEx) and a commercial building owner to evaluate leading-edge technologies on a 40,000 ft2 floor in an occupied, high-rise commercial office building in New York, New York. This {\textquotedblleft}Living Laboratory{\textquotedblright} was monitored for a year prior to and six months following the installation of four sets of lighting and shading technologies and their performance was compared to a parallel reference floor in the same building.

The Living Laboratory demonstrated that there were many competitive products on the market, that the products were able to meet current needs, and that the various advanced features provided significant added value over and above that of conventional products. Monitored data provided detailed insights into how and why each technology performed the way it did, and what the impacts were on energy-efficiency, peak demand, visual and thermal comfort, indoor environmental quality, and occupant acceptance and satisfaction within the resultant environment.

}, author = {Eleanor S. Lee and Luis L. Fernandes and Taoning Wang and Stephen E. Selkowitz and Steven Mesh and Yetsuh Frank and Richard Yancey} } @article {60938, title = {Balancing daylight, glare, and energy-efficiency goals: An evaluation of exterior coplanar shading systems using complex fenestration modeling tools}, journal = {Energy and Buildings}, volume = {112}, year = {2016}, month = {01/2016}, pages = {279-298}, abstract = {

Exterior shades are the most effective way to control solar load in buildings. Twelve different coplanar shades with different geometry, material properties and cut-off angles were investigated for two California climates: the moderate San Francisco Bay Area climate and a hot and dry Southern California climate. The presented results distinguish themselves from other simulation studies by a newly developed method that combines three research-grade software programs (Radiance, EnergyPlus and Window 7) to calculate heat transfer, daylight, and glare resulting from optically-complex fenestration systems more accurately. Simulations were run for a case with constant electric lighting and a case with daylighting controls for a prototypical, internal load dominated office building.

In the case of daylighting controls, the choice of slat angle and solar cut-off angle of a fixed exterior slat shading system is non trivial. An optimum slat angle was identified for the considered cases. Material properties (e.g., solar and visible reflectance) did not affect energy use if constant electric lighting was assumed, but they did have a significant influence on energy use intensity (EUI) when daylighting controls were assumed. Energy use increased substantially when an additional interior shade was used for glare control.

}, keywords = {Complex fenestration systems, Discomfort Glare, Energy Plus, Energy Use Intensity, Exterior shades, Glare Control, radiance}, doi = {10.1016/j.enbuild.2015.12.009}, author = {Sabine Hoffmann and Eleanor S. Lee and Andrew McNeil and Luis L. Fernandes and Dragan Vidanovic and Anothai Thanachareonkit} } @techreport {29804, title = {Technology Assessments of High Performance Envelope with Optimized Lighting, Solar Control, and Daylighting}, year = {2016}, month = {09/2016}, institution = {Lawrence Berkeley National Laboratory}, address = {Berkeley, CA}, abstract = {

Innovative, cost-effective, energy efficiency technologies and strategies for new and retrofit construction markets are essential for achieving near-term, broad market impacts. This study focuses on innovative shading and daylighting technologies that have the potential to significantly curtail annual cooling and lighting electricity use and reduce summer peak electric demand, particularly in the hot, sunny, inland areas where there has been significant population growth.

The building industry is well aware that energy-efficiency potential does not always match actual, real world performance in the field due to a variety of mitigating factors. Third party verification of the energy savings potential of innovative technologies is important for market adoption. In the case of shading and daylighting technologies, new simulation tools have only recently been developed to improve modeling accuracy. Market acceptance is also heavily dependent on how well the technology balances comfort and indoor environmental quality (IEQ) requirements (e.g., view, brightness, etc.). PG\&E commissioned this full-scale monitored study to better understand the impact of mitigating factors on performance so as to make more informed decisions when constructing program interventions that support technology adoption in the market.

}, author = {Eleanor S. Lee and Anothai Thanachareonkit and Samir Touzani and Spencer M. Dutton and Jordan Shackelford and Darryl J. Dickerhoff and Stephen E. Selkowitz} } @proceedings {60933, title = {Discomfort glare with complex fenestration systems and the impact on energy use when using daylighting control}, journal = {10th International Conference on Advanced Building Skins}, year = {2015}, month = {11/2015}, address = {Bern, Switzerland}, keywords = {building simulation, Complex fenestration systems, daylighting control, Discomfort Glare, Energy Use Intensity, radiance}, author = {Sabine Hoffmann and Andrew McNeil and Eleanor S. Lee and Raghuram Kalyanam} } @techreport {60776, title = {Electrochromic Window Demonstration at the Donna Land Port of Entry}, year = {2015}, month = {05/2015}, abstract = {

The U.S. General Services Administration (GSA) Public Buildings Service (PBS) has jurisdiction, custody or control over 105 land ports of entry throughout the United States, 35 of which are located along the southern border. At these facilities, one of the critical functions of windows is to provide border control personnel with direct visual contact with the surrounding environment. This also can be done through surveillance cameras, but the high value that U.S. Customs and Border Protection (CPB) officers place on direct visual contact can be encapsulated in the following statement by a senior officer regarding this project: {\textquotedblleft}nothing replaces line of sight.{\textquotedblright} In sunny conditions, however, outdoor visibility can be severely compromised by glare, especially when the orb of the sun is in the field of view. This often leads to the deployment of operable shading devices, such as Venetian blinds. While these devices address the glare, they obstruct the view of the surroundings, negating the visual security benefits of the windows.

Electrochromic (EC) windows have the ability to adjust their tint dynamically in response to environmental conditions. This provides the potential to control glare by going to a dark tint at times when extreme glare is likely. In previous studies, these windows have shown that this ability to control glare has the potential to increase the amount of time during which view is unobstructed. This technology is available in the U.S. as a commercial product from two vendors with high-capacity manufacturing facilities, and could be deployed on a nationwide scale if successful in a pilot test.

In this project, EC windows were installed at a land port of entry near Donna, Texas. The technical objectives of the study were to determine whether the installation of the EC windows resulted in the following:

}, author = {Luis L. Fernandes and Eleanor S. Lee and Anothai Thanachareonkit} } @article {60093, title = {Measured daylighting potential of a static optical louver system under real sun and sky conditions}, journal = {Building and Environment}, volume = {92}, year = {2015}, month = {10/2015}, pages = {347-359}, chapter = {347}, abstract = {

By utilizing highly specular surfaces and engineered profile geometry, optical sunlight redirecting systems integrated into the overhead {\textquotedblleft}clerestory{\textquotedblright} zone of the building facade present the potential to enlarge the daylighting zone by redirecting the luminous flux incident on the window deeper into the space than conventional shading systems. In addition, by developing system geometry to redirect daylight to specific zones within the space, optical light redirecting systems have the potential to avoid the glare conditions commonly produced by conventional facade shading systems that direct significant amounts of daylight below head height into the occupant{\textquoteright}s field of view. In this case study, side-by-side comparisons were made over solstice-to-solstice changes in sun and sky conditions between an optical louver system (OLS) and a conventional Venetian blind set at a horizontal slat angle and located inboard of a south-facing, small-area, clerestory window in a full-scale office testbed. Daylight autonomy (DA), window luminance, and ceiling luminance uniformity were used to assess performance. The performance of both systems was found to have significant seasonal variation, where performance under clear sky conditions improved as maximum solar altitude angles transitioned from solstice to equinox. Although the OLS produced fewer hours per day of DA on average than the Venetian blind, the OLS never exceeded the designated 2000\ cd/m2 threshold for window glare. In contrast, the Venetian blind was found to exceed the visual discomfort threshold over a large fraction of the day during equinox conditions (from 40 to 64\% of the test day between August 22 and October 12). Notably, these peak periods of visual discomfort occurred during the best periods of daylighting performance. Luminance uniformity was analyzed using calibrated high dynamic range luminance images. Under clear sky conditions, the OLS was found to increase the luminance of the ceiling as well as produce a more uniform distribution of luminance over the ceiling. Compared to conventional venetian blinds, the static optical sunlight redirecting system studied has the potential to significantly reduce the annual electrical lighting energy demand of a daylit space and improve the quality from the perspective of building occupants by consistently transmitting useful daylight while eliminating window glare.

}, keywords = {daylighting, field measurements, high dynamic range luminance images, optical louver system, sunlight redirecting system}, doi = {10.1016/j.buildenv.2015.04.024}, author = {Kyle S. Konis and Eleanor S. Lee} } @conference {60094, title = {Potential energy savings with exterior shades in large office buildings and the impact of discomfort glare}, booktitle = {Fourth BEST Conference Building Enclosure Science \& Technology (BEST4)}, year = {2015}, month = {04/2015}, address = {Kansas City, Missouri}, abstract = {

Exterior shades are highly efficient for reducing solar load in commercial buildings. Their impact on net energy use depends on the annual energy balance of heating, cooling, fan and lighting energy. This paper discusses the overall energy use intensity of various external shading systems for a prototypical large office building split into the different types of energy use and for different orientations and window sizes. Lighting energy was calculated for a constant lighting power as well as for dimmed lighting fixtures (daylighting control).

In Section 3, slat angles and solar cut-off angles were varied for fixed exterior slat shading systems. While the most light-blocking shades performed best for the case without daylighting controls, the optimum cut-off angle with daylighting controls was found to be 30 deg for the office building prototype used in Chicago and Houston. For large window-to-wall (WWR) ratios, window related annual energy use could be reduced by at least 70 \% without daylighting control and by a minimum of 86 \% with daylighting control in average over all orientations.

The occurrence of discomfort glare was is considered in Section 4 of the paper, which looks at the performance of commercially available exterior shading systems when an interior shade is used in addition to the exterior shade during hours when occupants would experience discomfort glare. Glare control impacts overall energy use intensity significantly for exterior shades with high transmittance, especially when daylighting controls are used. In these cases, exterior shades are only beneficial for window-to-wall areas >= 45\% in the hot Houston climate. For smaller windows and in a heating/cooling climate like Chicago, exterior shades can increase energy consumption.

}, author = {Sabine Hoffmann and Eleanor S. Lee} } @techreport {58592, title = {Angular selective window systems: Assessment of technical potential for energy saving}, year = {2014}, note = {

Submitted to Energy and Buildings, May 27, 2014

}, month = {01/2014}, pages = {36}, type = {DOE / CEC PIER Technical Report}, abstract = {

Static angular selective shading systems block or filter direct sunlight and admit daylight within a specific range of incident solar angles. They can potentially deliver energy efficient performance within the typical 4.6-m (15-ft) deep perimeter zone of buildings when tailored to a specific fa{\c c}ade orientation and latitude. The objective of this study is to quantify the technical potential of these systems to reduce energy use and peak demand in commercial buildings, specifically: a) achieve 30-50\% reductions in perimeter zone energy use vs. ASHRAE 90.1-2004, b) constrain peak window loads to less than 43 W/m2-floor (4 W/ft2-floor), and c) to the extent possible, admit useful daylight in the perimeter zone without exceeding the peak solar load constraint. Three distinctly different commercial shading systems were evaluated: a micro-perforated screen, a tubular shading structure (double- and triple-paned configurations), and an expanded metal mesh. This evaluation was performed mainly through computer simulation for a multitude of scenarios, including multiple climates (Chicago, Illinois and Houston, Texas), window-to-wall ratios (0.15-0.60), building codes (ASHRAE 90.1-2004 and 2010) and lighting control configurations (with and without daylighting controls). Angular selective shading systems are optically complex and cannot be modeled accurately using conventional simulation tools, prompting the development of unique versions of the EnergyPlus, Radiance and Window simulation tools. Results show significant potential reductions in perimeter zone energy use, with the best commercially-available system reaching 28\% and 47\% savings, relative to ASHRAE 90.1- 2004 and respectively without and with daylighting controls, on south facades in Chicago with WWR=0.45, while constraining peak window heat gains to under 43 W/m2-floor, and enabling significant savings from daylighting controls. Results suggest that it is possible that existing systems can be improved to more consistently achieve 30-50\% energy savings. Level of angular selectivity, spectral selectivity of low-e coatings and thermal conductance of the angle-selective layer were identified as critical factors for the performance of angular selective systems. Static, angular selective shading systems offer a potentially low-cost option to significantly reduce window heat gains and control glare from visibility of the sun orb, while permitting the admission of useful daylight and access to views to the outdoors. This type of system shows significant potential to contribute towards net-zero energy goals in both new and retrofit construction.

}, keywords = {angular selective systems, Building energy-efficiency, daylighting, Shading Systems, windows}, author = {Luis L. Fernandes and Eleanor S. Lee and Andrew McNeil and Jacob C. Jonsson and Thierry Stephane Nouidui and Xiufeng Pang and Sabine Hoffmann} } @article {58926, title = {Asymmetric particle fluxes from drifting ionization zones in sputtering magnetrons}, journal = {Plasma Sources Science and Technology}, volume = {23}, year = {2014}, month = {04/2014}, pages = {025007}, abstract = {

Electron and ion fluxes from direct current and high-power impulse magnetron sputtering (dcMS and HiPIMS) plasmas were measured in the plane of the target surface. Biased collector probes and a particle energy and mass analyzer showed asymmetric emission of electrons and of singly and doubly charged ions. For both HiPIMS and dcMS discharges, higher fluxes of all types of particles were observed in the direction of the electrons{\textquoteright} E x B drift. These results are put in the context with ionization zones that drift over the magnetron{\textquoteright}s racetrack. The measured currents of time-resolving collector probes suggest that a large fraction of the ion flux originates from drifting ionization zones, while energy-resolving mass spectrometry indicates that a large fraction of the ion energy is due to acceleration by an electric field. This supports the recently proposed hypothesis that each ionization zone is associated with a negative{\textendash}positive{\textendash}negative space charge structure, thereby producing an electric field that accelerates ions from the location where they were formed.

}, keywords = {Instrumentation and measurement, Plasma physics, Surfaces, interfaces and thin films}, issn = {0963-0252}, doi = {10.1088/0963-0252/23/2/025007}, author = {Matjaž Panjan and Robert Franz and Andr{\'e} Anders} } @article {1205, title = {Award of Excellence Winner Selkowitz Drives the Nation Toward Better Performing Buildings}, journal = {Engineering News-Record}, year = {2014}, month = {04/07/2014}, pages = {Acceptance speech for the Engineering News-Record, Award of Excellence, April 3, 2014}, publisher = {ENR.com}, url = {http://enr.construction.com/people/awards/2014/0407-Award-of-Excellence-Winner-Selkowitz-Drives-the-Nation-Toward-Better-Performing-Buildings.asp}, author = {Nadine M. Post} } @techreport {58905, title = {COMFEN {\textendash} Early Design Tool for Commercial Facades and Fenestration Systems}, year = {2014}, month = {03/2014}, abstract = {

California leads the nation in building energy efficiency standards and is a leader in the United States for legislation to reduce greenhouse gas emissions. Achieving these goals in practice requires that design teams and owners have access to technologies, systems and decision support tools that support their design work. This California Energy Commission funded work on the COMFEN software tool, which gives building practitioners, such as architects and engineers, the ability to assess the energy consequences of building design decisions, is thus a key enabling element that supports the AEC community in achieving ever more stringent performance requirements. COMFEN can provide needed building design guidance to not achieve the shorter term code goals but supports more aggressive achievement of the net-zero energy performance and peak load reduction required for all new buildings by 2030 as well as supporting deep retrofit of existing building stock.

Achieving a net-zero energy building cannot be done solely by improving the efficiency of the engineering systems (HVAC, lighting, equipment). It also requires consideration of the essential nature of the building starting early in the design process, including factors such as architectural form, massing, orientation and enclosure. Making informed decisions about the fundamental character of a building requires continuous assessment of the effects of the complex interaction of these factors on the resulting performance of the building as the design evolves. The complexity of these interactions necessitates the use of modeling and simulation tools to dynamically analyze the effects of the relationships. Decisions about the building fundamentals are often made in the earliest stages of design, before a complete {\textquoteright}building{\textquoteright} exists to model so that a focus on representative spaces in the building allows earlier guidance for the decision making.

COMFEN, an early-design energy modeling tool developed by LBNL, is designed specifically to make informed decisions about building fundamentals by considering the design of the building envelope, orientation and massing on building performance. It supports exploratory work early in the process by architects but is also useful for engineers and consultants later in the design process. It also supports innovation broadly as it allows teams to model new technologies and systems that are becoming available but have not yet reached mainstream status.

COMFEN focuses on the concept of a "space" or "room" and uses the EnergyPlus and Radiance{\texttrademark} engines and a simple, graphic user interface to allow the user to explore the effects of changing key early-design input variables for the fa{\c c}ade, internal loads, lighting controls and HVAC system on energy consumption, peak energy demand, and thermal and visual comfort. COMFEN also provides the ability to import glazing systems that have been developed in Window7, utilizing the International Glazing DataBase (IGDB) for glass choices. Comparative results are rapidly presented in a variety of graphic and tabular formats to help users move toward optimal fa{\c c}ade and fenestration design choices.

While the underlying simulation engines were developed over time as part of DOE{\textquoteright}s national windows and daylighting program, the specific design features of COMFEN were evolved over a several year period by consulting with a series of largely California-based architectural and engineering firms who provided important guidance and feedback on desirable features and then on functionality once the features were implemented.

COMFEN is available at no charge on the LBNL website.

}, author = {Stephen E. Selkowitz and Robert J. Hitchcock and Robin Mitchell and Maurya McClintock and Kevin Settlemyre} } @article {58925, title = {Drifting Ionization Zone in DC Magnetron Sputtering Discharges at Very Low Currents}, journal = {IEEE Transactions on Plasma Science}, volume = {42}, year = {2014}, month = {10/2014}, pages = {2578 - 2579}, abstract = {

Discharges with crossed electric and magnetic fields are known to develop instabilities that are crucial in the transport of charged particles. Sputtering magnetrons are no exception. While most recent studies focused on traveling ionization zones in high power impulse magnetron sputtering, we show here fast camera images of magnetron discharges at very low current. A single drifting ionization zone is always present, even down to the threshold current of about 10 mA.

}, issn = {0093-3813}, doi = {10.1109/TPS.2014.2334601}, author = {Andr{\'e} Anders and Pavel A Ni and Joakim Andersson} } @techreport {60771, title = {High Performance Building Fa{\c c}ade Solutions-Phase II}, year = {2014}, month = {03/2014}, abstract = {

The High Performance Building Fa{\c c}ade Solutions{\textendash}Phase II project was initiated through the California Energy Commission{\textquoteright}s Public Interest Energy Research (PIER) program in July 2010 to support industry{\textquoteright}s development and deployment of both incremental and breakthrough fa{\c c}ade technologies in partnership with the U.S. Department of Energy (DOE). The objective of this three-year project was to develop, or support the development and deployment of, promising near-term and emerging zero net energy building fa{\c c}ade technologies for solar control and daylighting, addressing two of the largest end uses in California commercial buildings: cooling and lighting. In partnership with industry (such as manufacturers), three classes of technologies were investigated: daylighting systems, angular-selective shading systems, and dynamic fa{\c c}ade systems. Commercially available and emerging prototype technologies were developed and evaluated using laboratory tests. Simulations, full-scale outdoor tests in the Advanced Window Testbed, and demonstration projects quantified energy and peak electric demand reductions and occupant satisfaction, acceptance, and comfort associated with the resultant indoor environment. Several new technologies were developed using virtual prototyping tools. Integrated control systems were developed using model predictive controls. Simulation tools were developed to model operable complex fenestration systems such as shades and microprismatic films. A schematic design tool called COMFEN was developed to facilitate evaluation of these advanced technologies in the early design phase. All three classes of technologies resulted in significant reductions in perimeter zone energy use and peak electric demand, providing viable options that can support California{\textquoteright}s long-term goal of achieving zero net energy use in the next decade.

}, keywords = {automated shading, between-pane shading, bidirectional scattering distribution functions, building energy simulation tools, Complex fenestration systems, daylighting, daylighting simulation tools, electrochromics, exterior shading, goniophotometer, light shelves, microprismatic films, model predictive controls, motorized shading, shading, solar-optical properties, switchable windows, thermochromics, virtual prototyping, window heat transfer}, author = {Eleanor S. Lee and Brian E. Coffey and Luis L. Fernandes and Sabine Hoffmann and Andrew McNeil and Anothai Thanachareonkit and Gregory J. Ward} } @techreport {61021, title = {High Performance Building Mockup in FLEXLAB}, year = {2014}, month = {12/2014}, institution = {Lawrence Berkeley National Laboratory}, address = {Berkeley, CA}, abstract = {

Genentech has ambitious energy and indoor environmental quality performance goals for Building 35 (B35) being constructed by Webcor at the South San Francisco campus. Genentech and Webcor contracted with the Lawrence Berkeley National Laboratory (LBNL) to test building systems including lighting, lighting controls, shade fabric, and automated shading controls in LBNL{\textquoteright}s new FLEXLAB facility. The goal of the testing is to ensure that the systems installed in the new office building will function in a way that reduces energy consumption and provides a comfortable work environment for employees.

LBNL tested three facades of the new office building in the rotating FLEXLAB testbed: west, south and east. External shading, lighting, and internal shading control was configured for each orientation to replicate the conditions of B35. The three facades were each tested for one week three times between July and October 2014. Changes were made between each test to improve the performance of the systems.

Linear pendant LED light fixtures will illuminate the open office areas of the office building. These fixtures were installed in FLEXLAB. The wide spacing between rows of light fixtures results in a low lighting power density of 0.57 W/ft2 in the open office areas, while still meeting the average illuminance criteria of 300 lux (28 footcandles). A combination of the wide spacing and optics of the light fixture creates a nonuniform lighting pattern on the ceiling of the space. Changing to a diffuse lens on the uplight will help reduce abrupt changes in luminance on the ceiling but non-uniformity will persist due to the wide spacing.

The pendant light fixtures allow separate control of the downward and upward light. The lighting control design aims to enhance the quality of space by dimming upward light unison providing uniform patterns of electric light on the ceiling. The downward light of each fixture dims to provide just enough light to meet illuminance criteria below the fixture.

Webcor installed two lighting control systems manufactured by Enlighted and Encelium for testing in FLEXLAB. The Encelium system uses an open loop control architecture with a ceiling-mounted photosensor at each facade (inside of the automated shade). While there is greater variation in workplane illuminance provided by the Encelium system, the system is better able to control upward versus downward lighting and is able to control the lighting according to the lighting design intent. The architecture of the Encelium system offers more functional flexibility by allowing any input (sensors, switches etc.) or multiple inputs to affect any fixture.

The Enlighted control system uses closed loop architecture with two photosensors per fixture (one for upward light and one for downward light). The Enlighted system controlled the lights more precisely than the Encelium system to meet workplane illuminance requirements, however the upward versus downward light control did not behave according to the lighting design intent.

MechoSystems provided motorized window shades and automated control. The shades in each window had a different color fabric, one dark grey and one medium grey. Both shade fabrics were an open weave with 3\% openness. Genentech selected the dark colored shade because it provides a better view of the exterior compared to the lighter colored shade. Anecdotal evidence suggests that some occupants may experience direct glare with 3\% open fabric while other occupants will not experience glare under the same conditions. Visual discomfort during the worst case sunny winter condition was not evaluated. However, the east-facing orientation during the equinox period was exposed to low sun angles in the third test period so findings of just acceptable visual discomfort are expected to be similar to what might be experienced during the winter.

The shades operated as expected on sunny days (which was the predominant condition during the test period). The testing identified substantial potential energy savings for the lighting systems by stopping the shade above the sill, preventing the shade from completely covering the window and allowing the sun to shine deeper into the space through the bottom few inches of the window. On partly cloudy days, which occurred more frequently after our testing concluded, anecdotal evidence suggests that the shades could be raised more often. LBNL suggests that a second threshold be implemented which drops the shade partway to prevent direct glare from bright sun, but doesn{\textquoteright}t close the shade down to the height required to limit sunshine depth.

Thermal comfort analysis suggests that occupants seated near the shaded window will be comfortable around 80\% of the time. The 20\% of time where the observed conditions fall outside the ASHRAE Standard 55 are almost always due to occupants being cold in the morning. This discomfort is mostly driven by cold surrounding surfaces causing a low mean radiant temperature and overcooling from outside air during economizer mode. Only one thermal comfort station, located near the facade, was used for the experiment. Thermal comfort further from the facade is unknown but is likely to be better due to the increased distance from the relatively cold facade.

Visual comfort studies indicated that occupants could sit as close as 3.5 feet to the east and west facade and 2.5 feet to the south facade when facing parallel to the window. Occupants must sit further away from the window to be comfortable when facing the window directly. Occupants should be 3.5 feet away when facing the south facade, 4.5 feet away when facing the west facade and 5.5 feet away when facing the east facade. Thermal comfort studies show that sitting within 30 inches of the facade has a negligible effect on comfort ratings.

Daylighting controls reduced lighting energy use in FLEXLAB by 46\% for east facade, 34\% for south facade and 35\% for west facade over 30 feet deep perimeter zone between 7 AM and 7 PM local time at autumn equinox. Occupancy controls will further reduce lighting energy use, though they were not implemented for the test due to the cell being tested unoccupied.

Genentech, Webcor, and the architectural and engineering team had access to the FLEXLAB during and for a month following the test period to observe, work, and discuss operational issues with employees and staff. The project team made their own qualitative observations about the space in terms of view, adequacy of lighting and daylight levels, color, furniture placement, etc. The project team worked collaboratively with the LBNL team to fine tune details of component design, control settings, troubleshooting, and operations. Because Genentech is introducing a new model for their work environment, a non-assigned workplace, there were detailed discussions on how to educate the occupants about the new technologies and their operational modes. Commissioning and tuning procedures were also discussed.

}, keywords = {commercial buildings, daylighting, energy management control systems, exterior shading, field test, lighting controls, monitored evaluation, shading controls, thermal comfort, visual comfort}, author = {Andrew McNeil and Christian Kohler and Eleanor S. Lee and Stephen E. Selkowitz} } @article {55580, title = {Monitored lighting energy savings from dimmable lighting controls in The New York Times Headquarters Building}, journal = {Energy and Buildings}, volume = {68}, year = {2014}, month = {01/2014}, pages = {498-514}, chapter = {498}, abstract = {

Digital addressable, dimmable lighting controls were introduced to the US market in the early 2000s with the promise of facilitating capture of potential energy savings with greater flexibility over their historic, typically unreliable, analog counterpart. The New York Times Company installed this emerging technology, after having tested the system thoroughly prior to procurement, in their new building in New York, New York. Four years after full occupancy in 2007, the owner agreed to participate in a post-occupancy monitored evaluation of the dimmable lighting system to verify actual performance in the field. Annual lighting energy savings from daylighting, setpoint tuning and occupancy controls were determined for the daylit, open-plan office areas on three typical floors (6, 11, and 20th floors) of the 51-story high-rise tower. Energy savings were calculated from ballast control signal and occupancy data recorded by the manufacturer{\textquoteright}s lighting control system. The ballast data were calibrated with independent measurements of lighting energy consumption. Savings from dimming controls (daylighting and setpoint tuning) were 12.6 kWh/m2-yr (1.17 kWh/ft2-yr) for the daylit spaces on the three floors overall, or 20\%, relative to ASHRAE 90.1-2007. Compared to the prescriptive code in effect at the time of the building{\textquoteright}s construction (ASHRAE 90.1-2001), savings were 21.0 kWh/m2-yr (1.95 kWh/ft2-yr) or 28\%. Annual lighting energy use with all lighting control strategies was 33.9 kWh/m2-yr (3.15 kWh/ft2-yr) in the daylit, open plan zones on average for the three floors. A simple payback analysis was conducted.

}, keywords = {Building energy-efficiency, daylighting, lighting control systems}, doi = {10.1016/j.enbuild.2013.10.009}, author = {Luis L. Fernandes and Eleanor S. Lee and Dennis L. DiBartolomeo and Andrew McNeil} } @article {57094, title = {Acceleration of the matrix multiplication of Radiance three phase daylighting simulations with parallel computing on heterogeneous hardware of personal computer}, journal = {Journal of Building Performance Simulation}, year = {2013}, abstract = {

Building designers are increasingly relying on complex fenestration systems to reduce energy consumed for lighting and HVAC in low energy buildings. Radiance, a lighting simulation program, has been used to conduct daylighting simulations for complex fenestration systems. Depending on the configurations, the simulation can take hours or even days using a personal computer. This paper describes how to accelerate the matrix multiplication portion of a Radiance three-phase daylight simulation by conducting parallel computing on heterogeneous hardware of a personal computer. The algorithm was optimized and the computational part was implemented in parallel using OpenCL. The speed of new approach was evaluated using various daylighting simulation cases on a multicore central processing unit and a graphics processing unit. Based on the measurements and analysis of the time usage for the Radiance daylighting simulation, further speedups can be achieved by using fast I/O devices and storing the data in a binary format.

}, keywords = {daylighting simulation, graphics processing unit, multicore central processing unit, OpenCL, parallel computing}, doi = {10.1080/19401493.2013.795193}, author = {Wangda Zuo and Andrew McNeil and Michael Wetter and Eleanor S. Lee} } @techreport {57096, title = {Annual daylighting performance of a passive optical light shelf in sidelit perimeter zones of commercial buildings}, year = {2013}, abstract = {

Sunlight redirecting systems have the potential to significantly offset electric lighting energy use in deep perimeter zones of buildings where the windows are subject to high daylight availability. New Radiance modeling tools have recently been developed and validated, enabling accurate and timely simulation analysis of the annual energy and comfort performance of these optically-complex, anisotropic systems. A parametric study was conducted using these tools to evaluate the performance of a commercially-available passive optical light shelf (OLS) in a 17.4 m deep (57 ft), south-facing open plan office zone in three climates. Daylighting efficiency, discomfort glare, and lighting energy savings with continuous dimming and bi-level switching controls were determined at varying depths within the zone. The OLS decreased lighting energy use significantly throughout the depth of the space and achieved these savings with minimal discomfort glare in the area near the window. Annual lighting energy use intensity was reduced to 1.71-1.82 kWh/ft2-yr (22-27\%) over the full depth of the perimeter zone across the three climates modeled (Phoenix, Washington DC, and Minneapolis) compared to a non-daylit zone at 2.34 kWh/ft2-yr. There was a greater occurrence of discomfort glare (3-7\% during daytime work hours) if the occupant was in a seated view position looking at the window from the back of the room. The system is passive, needing no adjustment during the day and over the seasons and can be used as a retrofit measure in existing buildings. These results are encouraging and demonstrate how the primary daylit sidelit area can be extended well beyond the defined limits provided by the newly adopted ASHRAE 90.1-2010 code (i.e., 1.0 times the head height of the window).

}, keywords = {bidirectional scattering distribution functions, buildings energy efficiency, daylighting, Radiance simulations}, author = {Andrew McNeil and Eleanor S. Lee} } @techreport {58288, title = {Automated Production of Optimization-Based Control Logics for Dynamic Fa{\c c}ade Systems, with Experimental Application to Two-Zone External Venetian Blinds}, year = {2013}, month = {09/2013}, type = {CEC PIER Technical Report}, author = {Brian E. Coffey and Andrew McNeil and Thierry Stephane Nouidui and Eleanor S. Lee} } @booklet {1206, title = {BSDFViewer: A utility for interactive exploration of BSDF datasets}, year = {2013}, month = {09/2013}, abstract = {

BSDFViewer is a utility for interactive exploration of BSDF datasets. With BSDF view you can load a BSDF xml file and view the outgoing distribution for user-selectable incident directions. You can look at transmission or reflection for front or back.

}, url = {http://www.radiance-online.org/download-install/bsdf-viewer}, author = {Andrew McNeil} } @inbook {58280, title = {Complex Fenestration Calculation Module}, booktitle = {EnergyPlus Engineering Reference}, year = {2013}, month = {10/2013}, chapter = {Window Calculation Module}, abstract = {

This document is organized to give you the best possible look into the EnergyPlus calculations. First, the concepts of modeling in EnergyPlus are presented. These include descriptions of the zone heat balance process, air loop/plant loop processes as well as other important processes for the building simulation.

Discussions during the modeling process may reference specific "object names" as found in the Input/Output Reference document.

The remainder of the document focuses on individual models.

}, author = {Joseph H. Klems} } @techreport {1207, title = {Daylight performance of a microstructured prismatic window film in deep open plan offices}, year = {2013}, month = {09/2013}, abstract = {

Daylight redirecting systems with vertical windows have the potential to offset lighting energy use in deep perimeter zones. A microstructured prismatic film was designed and fabricated by a manufacturer to redirect sunlight to the ceiling plane when the film was installed in the upper portion of a window. Energy simulations based on the raytracing program, Radiance, were performed to evaluate the annual lighting energy use and discomfort glare in a deep open plan office zone in several climates and for south and east-facing window orientations. These simulations showed that when the prismatic film was combined with a light diffusing film, the system was able to deliver significant energy savings without glare.

}, author = {Andrew McNeil and Eleanor S. Lee and Jacob C. Jonsson} } @techreport {1208, title = {Designing improved angular-selective shading systems}, year = {2013}, month = {09/2013}, type = {DOE/ CEC PIER Technical Report}, author = {Luis L. Fernandes and Eleanor S. Lee} } @article {58924, title = {Drifting potential humps in ionization zones: The {\textquotedblleft}propeller blades{\textquotedblright} of high power impulse magnetron sputtering}, journal = {Applied Physics Letters}, volume = {103}, year = {2013}, month = {10/2013}, pages = {144103}, abstract = {

Ion energy distribution functions measured for high power impulse magnetron sputtering show features, such as a broad peak at several 10\ eV with an extended tail, as well as asymmetry with respect to E {\texttimes} B, where E and B are the local electric and magnetic field vectors, respectively. Here it is proposed that those features are due to the formation of a potential hump of several 10\ V in each of the traveling ionization zones. Potential hump formation is associated with a negative-positive-negative space charge that naturally forms in ionization zones driven by energetic drifting electrons.

}, keywords = {Electric fields, ionization, plasma ionization, sputter deposition, sputtering}, issn = {00036951}, doi = {10.1063/1.4823827}, author = {Andr{\'e} Anders and Matjaž Panjan and Robert Franz and Joakim Andersson and Pavel A. Ni} } @article {57097, title = {Empirical Assessment of a Prismatic Daylight-Redirecting Window Film in a Full-Scale Office Testbed}, journal = {LEUKOS: The Journal of the Illuminating Engineering Society of North America}, volume = {10}, year = {2013}, note = {

Illuminating Engineering Society (IES) Annual Conference 2013
Huntington Beach, CA,
26 - 29 October 2013

}, month = {10/2013}, pages = {19-45}, address = {Huntington Beach, California}, abstract = {

Daylight redirecting systems with vertical windows have the potential to offset lighting energy use in deep perimeter zones. Microstructured prismatic window films can be manufactured using low-cost, roll-to-roll fabrication methods and adhered to the inside surface of existing windows as a retrofit measure or installed as a replacement insulating glass unit in the clerestory portion of the window wall. A clear film patterned with linear, 50-250 micrometer high, four-sided asymmetrical prisms was fabricated and installed in the south-facing, clerestory low-e, clear glazed windows of a full-scale testbed facility. Views through the film were distorted. The film was evaluated in a sunny climate over a two-year period to gauge daylighting and visual comfort performance. The daylighting aperture was small (window-to-wall ratio of 0.18) and the lower windows were blocked off to isolate the evaluation to the window film. Workplane illuminance measurements were made in the 4.6 m (15 ft) deep room furnished as a private office. Analysis of discomfort glare was conducted using high dynamic range imaging coupled with the evalglare software tool, which computes the daylight glare= probability and other metrics used to evaluate visual discomfort.

The window film was found to result in perceptible levels of discomfort glare on clear sunny days from the most conservative view point in the rear of the room looking toward the window. Daylight illuminance levels at the rear of the room were significantly increased above the reference window condition, which was defined as the same glazed clerestory window but with an interior Venetian blind (slat angle set to the cut-off angle), for the equinox to winter solstice period on clear sunny days. For partly cloudy and overcast sky conditions, daylight levels were improved slightly. To reduce glare, the daylighting film was coupled with a diffusing film in an insulating glazing unit. The diffusing film retained the directionality of the redirected light= spreading it within a small range of outgoing angles. This solution was found to reduce glare to imperceptible levels while retaining for the most part the illuminance levels achieved solely by the daylighting film.

}, keywords = {buildings energy efficiency, daylighting, microstructure film, prismatic film, windows}, doi = {10.1080/15502724.2014.837345}, author = {Anothai Thanachareonkit and Eleanor S. Lee and Andrew McNeil} } @article {57039, title = {An empirical study of a full-scale polymer thermochromic window and its implications on material science development objectives}, journal = {Solar Energy Materials and Solar Cells}, volume = {116}, year = {2013}, month = {09/2013}, pages = {14-26}, chapter = {14}, abstract = {

Large-area polymer thermochromic (TC) laminated windows were evaluated in a full-scale testbed office. The TC interlayer film exhibited thermochromism through a ligand exchange process, producing a change in solar absorption primarily in the visible range while maintaining transparent, undistorted views through the material. The film had a broad switching temperature range and when combined to make an insulating window unit had center-of-glass properties of Tsol=0.12-0.03, Tvis=0.28-0.03 for a glass temperature range of 24-75{\textdegree}C. Field test measurements enabled characterization of switching as a function of incident solar irradiance and outdoor air temperature, illustrating how radiation influences glass temperature and thus effectively lowers the critical switching temperature of TC devices. This was further supported by EnergyPlus building energy simulations. Both empirical and simulation data were used to illustrate how the ideal critical switching temperature or temperature range for TC devices should be based on zone heat balance, not ambient air temperature. Annual energy use data are given to illustrate the energy savings potential of this type of thermochromic. Based on observations in the field,a broad switching temperature range was found to be useful in ensuring a uniform appearance when incident irradiance is non-uniform across the facade. As indicated in prior research, a high visible transmittance in both the switched and unswitched state is also desirable to enable reduction of lighting energy use and enhance indoor environmental quality.

}, keywords = {buildings energy efficiency, Solar control, Thermochromic, windows}, doi = {10.1016/j.solmat.2013.03.043}, author = {Eleanor S. Lee and Xiufeng Pang and Sabine Hoffmann and Howdy Goudey and Anothai Thanachareonkit} } @techreport {58692, title = {The Five-Phase Method for Simulating Complex Fenestration with Radiance}, year = {2013}, month = {09/2013}, abstract = {

The "five-phase method" is an extension of the three-phase method that more closely follows the standard daylight coefficient model for dynamic daylight simulations proposed by Bourgeois et al (2008). More specifically, the five-phase method handles the direct solar component separately from the sky and interreflected solar component to achieve better accuracy of the distribution of direct solar light in a room for complex glazing systems (CFS).

}, author = {Andrew McNeil} } @article {55433, title = {Lighting energy savings potential of split-pane electrochromic windows controlled for daylighting with visual comfort}, journal = {Energy and Buildings}, volume = {61}, year = {2013}, month = {06/2013}, pages = {8-20}, abstract = {

A simulation study was conducted to evaluate lighting energy savings of split-pane electrochromic (EC) windows controlled to satisfy key visual comfort parameters. Using the Radiance lighting simulation software, interior illuminance and luminance levels were computed for a south-facing private office illuminated by a window split into two independently-controlled EC panes. The transmittance of these was optimized hourly for a workplane illuminance target while meeting visual comfort constraints, using a least-squares algorithm with linear inequality constraints. Blinds were successively deployed until visual comfort criteria were satisfied. The energy performance of electrochromics proved to be highly dependent on how blinds were controlled. With hourly blind position adjustments, electrochromics showed significantly higher (62\% and 53\%, respectively without and with overhang)lighting energy consumption than clear glass. With a control algorithm designed to better approximate realistic manual control by an occupant, electrochromics achieved significant savings (48\% and 37\%, respectively without and with overhang). In all cases, energy consumption decreased when the workplace illuminance target was increased. In addition, the fraction of time during which the occupant had an unobstructed view of the outside was significantly greater with electrochromics: 10 months out of the year versus a handful of days for the reference case.

}, keywords = {Building energy-efficiency, Control optimization, daylighting, Electrochromic windows}, doi = {10.1016/j.enbuild.2012.10.057}, author = {Luis L. Fernandes and Eleanor S. Lee and Gregory J. Ward} } @article {58920, title = {Modeling of optical and energy performance of tungsten-oxide-based electrochromic windows including their intermediate states}, journal = {Solar Energy Materials and Solar Cells}, volume = {108}, year = {2013}, month = {1/2013}, pages = {129 - 135}, abstract = {

Tungsten-oxide-based electrochromic (EC) windows are currently the most robust and matured dynamic windows where the transmittance of visual light and near-infrared radiation can be controlled by a small applied voltage. In its standard application, the window is commonly either in its clear or colored state. In this contribution, we study the optical and energy performance of such window in the fully bleached and fully colored state as well as when it is kept in intermediate states. Different configurations in terms of placement of the EC layer stack and possible additional low-emissivity (low-E) coating within the insulated glass unit are considered. Using optical data and software tools we find that even a small coloration has a significant effect on the energy performance because the solar heat gain coefficient is readily reduced by the absorption of the EC layer stack. We compare the performance of the EC windows to commercially available solar-control (spectrally selective) low-E windows.

}, keywords = {Electrochromic windows, Energy efficient window modeling, Energy simulation, Smart windows}, issn = {09270248}, doi = {10.1016/j.solmat.2012.09.010}, author = {Sunnie H.N. Lim and Jan Isidorsson and Lizhong Sun and B. Leo Kwak and Andr{\'e} Anders} } @article {58230, title = {Near-Infrared Spectrally Selective Plasmonic Electrochromic Thin Films}, journal = {Advanced Optical Materials}, volume = {1}, year = {2013}, month = {03/2013}, pages = {215 - 220}, abstract = {

A plasmonic electrochromic effect in which electrochemical doping reversibly modulates near-infrared surface plasmon absorption of aluminium-doped zinc oxide and tin-doped indium oxide nanocrystals is reported. Optical performance, switching kinetics, and cycling durability point to high-performance NIR selective plasmonic electrochromic coatings based on earth-abundant materials.

}, keywords = {aluminum zinc oxide, indium tin oxide, nanocrystal, spectroelectrochemistry, surface plasmon}, doi = {10.1002/adom.201200051}, author = {Guillermo Garcia and Raffaella Buonsanti and Anna Llordes and Evan L. Runnerstrom and Amy Bergerud and Delia J. Milliron} } @techreport {60935, title = {A Pilot Demonstration of Electrochromic and Thermochromic Windows in the Denver Federal Center, Building 41, Denver, Colorado}, year = {2013}, note = {

Completed September 30, 2012, released March 30, 2014.

}, month = {07/2013}, abstract = {

Chromogenic glazing materials are emerging technologies that tint reversibly from a clear to dark tinted state either passively in response to environmental conditions or actively in response to a command from a switch or building automation system. Switchable coatings on glass manage solar radiation and visible light while enabling unobstructed views to the outdoors. Building energy simulations estimate that actively controlled, near-term chromogenic glazings can reduce perimeter zone heating, ventilation, and air- conditioning (HVAC) and lighting energy use by 10-20\% and reduce peak electricity demand by 20-30\%, achieving energy use levels that are lower than an opaque, insulated wall.

This project demonstrates the use of two types of chromogenic windows: thermochromic and electrochromic windows. By 2013, these windows will begin production in the U.S. by multiple vendors at high-volume manufacturing plants, enabling lower cost and larger area window products to be specified. Both technologies are in the late R\&D stage of development, where cost reductions and performance improvements are underway. Electrochromic windows have been installed in numerous buildings over the past four years, but monitored energy-efficiency performance has been independently evaluated in very limited applications. Thermochromic windows have been installed in one other building with an independent evaluation, but results have not yet been made public.

}, keywords = {building controls, daylighting, Demand Side Management, electrochromic, energy-efficiency, Smart windows, switchable windows, Thermochromic, Window}, url = {http://gsa.gov/portal/content/187967}, author = {Eleanor S. Lee and Luis L. Fernandes and Howdy Goudey and Jacob C. Jonsson and Dragan C. Curcija and Xiufeng Pang and Dennis L. DiBartolomeo and Sabine Hoffmann} } @techreport {3441, title = {A Post-Occupancy Monitored Evaluation of the Dimmable Lighting, Automated Shading, and Underfloor Air Distribution System in The New York Times Building}, year = {2013}, month = {01/2013}, institution = {Lawrence Berkeley National Laboratory}, address = {Berkeley, CA}, abstract = {

With aggressive goals to reduce national energy use and carbon emissions, the US Department of Energy will be looking to exemplary buildings that have already invested in new approaches to achieving the energy performance goals now needed at a national level. The New York Times Building, in New York, New York, incorporates a number of innovative technologies, systems and processes and could become a model for widespread replication in new and existing buildings. Post-occupancy data are invaluable in establishing confidence in innovation. A year-long monitored study was conducted to verify energy performance, assess occupant comfort and satisfaction with the indoor environment, and evaluate impacts on maintenance and operations. Lessons learned were derived from the analysis; these lessons could help identify and shape policy, financial, or supporting strategies to accelerate diffusion in the commercial building market.

}, author = {Eleanor S. Lee and Luis L. Fernandes and Brian E. Coffey and Andrew McNeil and Robert D. Clear and Thomas L. Webster and Fred S. Bauman and Darryl J. Dickerhoff and David Heinzerling and Tyler Hoyt} } @article {58229, title = {Regional performance targets for transparent near-infrared switching electrochromic window glazings}, journal = {Building and Environment}, volume = {61}, year = {2013}, month = {03/2013}, pages = {160 - 168}, abstract = {

With building heating and cooling accounting for nearly 14\% of the national energy consumption, emerging technologies that improve building envelope performance have significant potential to reduce building energy consumption. Actual savings from these technologies will depend heavily upon their performance in diverse climate and operational conditions. In many cases, early-stage research can benefit from detailed investigation in order to develop performance thresholds and identify target markets. One example, a dynamic, highly transparent, near-infrared switching electrochromic (NEC) window glazing, is the focus of this investigation. Like conventional electrochromics, the NEC glazing can dynamically tune its optical properties with a small applied voltage. Consequently, the glazing can block or transmit solar heat to reduce cooling or heating loads, respectively. Unlike conventional electrochromics, NEC glazings remain transparent to visible light, causing no adverse effect to daylighting or building aesthetics. This study utilizes the software COMFEN to simulate a broad range of NEC performance levels, for commercial and residential buildings in 16 climate-representative reference cities. These simulations are the basis for identifying performance levels necessary to compete with existing static technologies. These results indicate that energy savings are strongly influenced by blocking-state performance. Additionally, residential applications have lower performance requirements due to their characteristic internal heat gains. Finally, the most dynamic NEC performance level is simulated in competition with high performing static alternatives. Here heating and cooling energy savings range from 5 to 11\ kWh/m2 yr for commercial and 8{\textendash}15\ kWh/m2 yr for residential, in many regions on the order of 10\%.

}, keywords = {Dynamic windows, Electrochromic glazings, NIR-switching, Performance targets, Solar heat gain}, issn = {03601323}, doi = {10.1016/j.buildenv.2012.12.004}, author = {Nicholas DeForest and Arman Shehabi and Guillermo Garcia and Jeffery B. Greenblatt and Eric R. Masanet and Eleanor S. Lee and Stephen E. Selkowitz and Delia J. Milliron} } @techreport {58686, title = {Simulated daylight performance of a new prototype prismatic window film in deep open plan offices}, year = {2013}, month = {09/2013}, type = {DOE/ CEC PIER Technical Report}, author = {Andrew McNeil and Eleanor S. Lee} } @article {58927, title = {Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas}, journal = {Applied Physics Letters}, volume = {103}, year = {2013}, month = {07/2013}, pages = {054104}, abstract = {

Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side-on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.

}, keywords = {Aluminium, ionization, Ionizing radiation, plasma ionization, visible spectra}, issn = {00036951}, doi = {10.1063/1.4817257}, author = {Joakim Andersson and Pavel A Ni and Andr{\'e} Anders} } @techreport {1209, title = {Theory documentation for software to control the pgII phirot2 automated sample mount and analyzing data obtained}, year = {2013}, month = {09/2013}, address = {Berkeley}, abstract = {

The phirot2 sample holder is a device used for controlling the angle of incidence for anisotropic samples with the pgII photogoniometer.

The first topic covered is how to control the instrument using the allmess command line tool which allows the measurement sequence to be more flexible than the pgc GUI tool usually used for control. A method to monitor drift over long measurement sessions is also covered. Tangential to this is several syntax examples of how bash shell script is used to call allmess. Code to generate bash scripts for samples with different degree of symmetry is discussed as well as how to modify a script to continue from a certain point if a measurement was aborted.

The second half of the document describes how to access the data and compile the data into the Klems XML format. A path for future combination with the Radiance interpolation format is also given.

Finally verification and visualization of BSDF data is discussed.

}, author = {Jacob C. Jonsson} } @techreport {1210, title = {The three-phase method for simulating complex fenestration with Radiance}, year = {2013}, month = {08/2013}, type = {Tutorial}, abstract = {

The "three-phase method" is a means to perform annual simulation of complex and/or dynamic fenestration systems. Flux transfer is broken into the following three phases for independ ent simulation:

  1. Sky to exterior of fenestration
  2. Transmission through fenestration
  3. Interior of fenestration into the simulated space

Rather than simulate a specific daylight condition, the three-phase method calculates normalized coefficients that relate flux input to output for each phase. A result for a specific daylight condition is computed by multiplying the coefficient matrices by the input values (sky luminance values). Matrix calculation can be performed very quickly enabling the user to simulate many sky conditions and fenestration transmission properties.

This document starts with a brief overview of the three-phase method. Following is a detailed discussion of each phase of flux transfer including an explanation of new tools that were develop ed for the three - phase method, explained in detail. Two examples follow the detailed discussion, the first a simple space with one south facing window, the second a space with south and east facing windows.

}, author = {Andrew McNeil} } @techreport {58691, title = {Tips for Daylighting with Windows: The Integrated Approach, 2nd Edition}, year = {2013}, abstract = {

These guidelines provide an integrated approach to the cost-effective design of perimeter zones in new commercial buildings and existing building retrofits. They function as a quick reference for building designers, through a set of easy steps and rules-of-thumb, emphasizing "how-to" practical details. References are given to more detailed sources of information, should the reader wish to go further.

The design method used in this document emphasizes that building decisions should be made within the context of the whole building as a single functioning system rather than as an assembly of distinct parts. This integrated design approach looks at the ramifications of each individual system decision on the whole building. For example, the decision on glazing selection will have an effect on lighting, mechanical systems, and interior design. Therefore, the entire design team should participate and influence this glazing decision{\textemdash}which typically rests with the architect alone. The benefit of an integrated design approach is a greater chance of success towards long-term comfort and sustained energy savings in the building.

}, author = {Jennifer Schumann and Eleanor S. Lee and Francis M. Rubinstein and Stephen E. Selkowitz and Alastair Robinson} } @article {57807, title = {U.S. energy savings potential from dynamic daylighting control glazings}, journal = {Energy and Buildings}, volume = {66}, year = {2013}, month = {11/2013}, pages = {415-423}, chapter = {415}, abstract = {

Daylighting controls have the potential to reduce the substantial amount of electricity consumed for lighting in commercial buildings. Material science research is now pursuing the development of a dynamic prismatic optical element (dPOE) window coating that can continuously readjust incoming light to maximize the performance and energy savings available from daylighting controls. This study estimates the technical potential for energy savings available from vertical daylighting strategies and explores additional savings that may be available if current dPOE research culminates in a successful market-ready product. Radiance daylight simulations are conducted with a multi-shape prismatic window coating. Simulated lighting energy savings are then applied to perimeter floorspace estimates generated from U.S. commercial building stock data. Results indicate that fully functional dPOE coatings, when paired with conventional vertical daylight strategies, have the potential to reduce energy use associated with U.S. commercial electric lighting demand by as much as 930 TBtu. This reduction in electric lighting demand represents an approximately 85\% increase in the energy savings estimated from implementing conventional vertical daylight strategies alone. Results presented in this study provide insight into energy and cost performance targets for dPOE coatings, which can help accelerate the development process and establish a successful new daylighting technology.

}, keywords = {Clerestories, daylighting, Dynamic prismatic optical elements (dPOE), energy efficiency, Glare, indoor environmental quality, radiance, windows}, doi = {10.1016/j.enbuild.2013.07.013}, author = {Arman Shehabi and Nicholas DeForest and Andrew McNeil and Eric R. Masanet and Jeffery B. Greenblatt and Eleanor S. Lee and Georgeta Masson and Brett A. Helms and Delia J. Milliron} } @article {57298, title = {A validation of a ray-tracing tool used to generate bi-directional scattering distribution functions for complex fenestration systems}, journal = {Solar Energy}, volume = {98}, year = {2013}, month = {12/2013}, pages = {404-414}, abstract = {

Fenestration attachments are anticipated to produce significant reductions in building energy use because they can be deployed quickly at low-cost. New software tools enable users to assess the building energy impacts of optically complex fenestration systems (CFS) such as shades, Venetian blinds, or daylighting systems. However, such tools require users to provide bi-directional scattering distribution function (BSDF) data that describe the solar-optical performance of the CFS. A free, open-source Radiance tool genBSDF enables users to generate BSDF data for arbitrary CFS. Prior to genBSDF, BSDF data for arbitrary fenestration systems could only be produced using either expensive software or with expensive equipment. genBSDF outputs CFS data in the Window 6 XML file format and so can be used with CFS-enabled software tools to model multi-layered window systems composed of glazing and shading layers.

We explain the basis and use of the genBSDF tool and validate the tool by comparing results for four different cases to BSDF data produced via alternate methods. This validation demonstrates that BSDFs created with genBSDF are comparable to BSDFs generated analytically using TracePro and by measurement with a scanning goniophotometer. This tool is expected to support accelerated adoption of fenestration attachments and daylighting technologies.

}, keywords = {Bi-directional scattering distribution function, Complex fenestration systems, daylighting, Solar heat gain}, doi = {10.1016/j.solener.2013.09.032}, author = {Andrew McNeil and Jacob C. Jonsson and Appelfeld, David and Gregory J. Ward and Eleanor S. Lee} } @conference {57409, title = {Application of a stochastic window use model in EnergyPlus}, booktitle = {SimBuild 2012, 5th National Conference of IBPSA-USA, August 1-3, 2012}, year = {2012}, month = {08/2012}, address = {Madison, WI}, abstract = {

Natural ventilation, used appropriately, has the potential to provide both significant HVAC energy savings, and improvements in occupant satisfaction.

Central to the development of natural ventilation models is the need to accurately represent the behavior of building occupants. The work covered in this paper describes a method of implementing a stochastic window model in EnergyPlus. Simulated window use data from three stochastic window opening models was then compared to measured window opening behavior, collected in a naturally-ventilated office in California. Recommendations regarding the selection of stochastic window use models, and their implementation in EnergyPlus, are presented.

}, url = {https://escholarship.org/uc/item/2gm7r783}, author = {Spencer M. Dutton and Hui Zhang and Yongchao Zhai and Edward A. Arens and Youness Bennani Smires and Samuel L. Brunswick and Kyle S. Konis and Philip Haves} } @techreport {58589, title = {On the benefits of a variable-resolution bidirectional scattering distribution data format}, year = {2012}, month = {09/2012}, pages = {5}, type = {DOE/ CEC PIER Technical Report Deliverable}, abstract = {

This summary report adds context to the recent development of a new format for variable-resolution bi-directional scattering data. Specifically we discuss why a high resolution BSDF format is needed, the advantages of a variable resolution data format, and the new capabilities that stem from this development.

}, author = {Andrew McNeil and Eleanor S. Lee} } @techreport {1211, title = {Conditioning anisotropic BSDF measurements for lighting and daylighting simulation}, year = {2012}, month = {09/2012}, type = {DOE/ LBNL FY12 Technical Report Deliverable}, address = {Berkeley}, abstract = {

This report describes the requirements for utilizing bidirectional scattering distribution function (BSDF) measurements produced by the PAB-Opto goniophotometer and similar devices in simulation tools such as Radiance, and describes progress to date in implementing these methods. An interpolation technique has been identified for resampling the measured data, and an initial implementation has been produced. Work continues on improving this technique and software so it may be employed in a streamlined process for reducing BSDF measurements to a usable form and distributed as variable-resolution XML data. This data may then be employed by lighting simulation software to model complex fenestration systems.

}, author = {Gregory J. Ward} } @techreport {1212, title = {Development of a simulation-based controls framework for implementation of controls algorithms for complex fenestration systems}, year = {2012}, month = {09/2012}, pages = {15}, type = {DOE/ CEC PIER Technical Report}, abstract = {

Effectively controlled dynamic windows can substantially reduce the energy consumption of buildings. Unfortunately, modular and extensible frameworks for testing and evaluating window system control algorithms that include the effects of thermal mass are missing in the research community.

This paper describes a modular and extensible simulation-based framework that uses different simulation tools such as EnergyPlus, Modelica, Radiance, and the Building Controls Virtual Test Bed (BCVTB) to develop and evaluate the performance of integrated fa{\c c}ade control strategies. We present a simulation framework and a proof-of concept application using the framework to control a venetian blind in a physical test cell in order to reduce its zone thermal load based on solar inputs and internal gains measured at the test cell.

}, author = {Thierry Stephane Nouidui and Andrew McNeil and Eleanor S. Lee} } @article {3185, title = {Discomfort Glare: What Do We Actually Know?}, journal = {Lighting Research and Technology}, volume = {April 2012}, year = {2012}, month = {05/2012}, abstract = {

Glare models were reviewed with an eye for missing conditions or inconsistencies. We found ambiguities as to when to use small source versus large source models, and as to what constitutes a glare source in a complex scene. We also found surprisingly little information validating the assumed independence of the factors driving glare.

A barrier to progress in glare research is the lack of a standardized dependent measure of glare. We inverted the glare models to predict luminance, and compared model predictions against the 1949 Luckiesh \& Guth data that form the basis of many of them. The models perform surprisingly poorly, particularly with regards to the luminance-size relationship and additivity. Evaluating glare in complex scenes may require fundamental changes to form of the glare models.

}, doi = {10.1177/1477153512444527}, author = {Robert D. Clear} } @article {58923, title = {Drifting localization of ionization runaway: Unraveling the nature of anomalous transport in high power impulse magnetron sputtering}, journal = {Journal of Applied Physics}, volume = {111}, year = {2012}, month = {03/2012}, pages = {053304}, abstract = {

The plasma over a magnetron{\textquoteright}s erosion {\textquotedblleft}racetrack{\textquotedblright} is not azimuthally uniform but concentrated in distinct dense ionization zones which move in the E x B direction with about 10\% of the electron E x B/B2 drift velocity. The ionization zones are investigated with a gated camera working in concert with a streak camera for Al, Nb, Cu, and W targets in Ar or Kr background gas. It is found that each ionization zone has a high plasma density edge, which is the origin of a plasma-generating electron jet leaving the target zone. Each region of strong azimuthal plasma density gradient generates an azimuthal electric field, which promotes the escape of magnetized electrons and the formation of electron jets and plasma flares. The phenomena are proposed to be caused by an ionization instability where each dense plasma zone exhibits a high stopping power for drifting high energy electrons, thereby enhancing itself.

}, keywords = {Cameras, ionization, Magnetic fields, Plasma density, plasma ionization}, issn = {00218979}, doi = {10.1063/1.3692978}, author = {Andr{\'e} Anders and Pavel A Ni and Albert Rauch} } @mastersthesis {58224, title = {Effective Daylighting: Evaluating Daylighting Performance in the San Francisco Federal Building from the Perspective of Building Occupants}, year = {2012}, month = {01/2012}, type = {PhD}, address = {Berkeley}, abstract = {

Commercial office buildings promoted as {\textquotedblleft}sustainable,{\textquotedblright} {\textquotedblleft}energy efficient,{\textquotedblright} {\textquotedblleft}green,{\textquotedblright} or {\textquotedblleft}high performance{\textquotedblright} often reference use of daylight as a key strategy for reducing energy consumption and enhancing indoor environmental quality. However, buildings are rarely studied in use to examine if the design intent of a sufficiently daylit and a visually comfortable work environment is achieved from the perspective of building occupants or how occupant use of shading devices may affect electrical lighting energy reduction from photocontrols. This dissertation develops a field-based approach to daylighting performance assessment that pairs repeated measures of occupant subjective response using a novel desktop polling station device with measurements of the physical environment acquired using High Dynamic Range (HDR) imaging and other environmental sensors with the objective of understanding the physical environmental conditions acceptable to occupants. The approach is demonstrated with a 6-month field study involving (N=44) occupants located in perimeter and core open-plan office spaces in the San Francisco Federal Building1 (SFFB). Over 23,100 subjective assessments paired with physical measures were analyzed to develop models of visual discomfort and shade control and to examine the assumptions of existing daylighting performance indicators. The analysis found that existing daylight performance indicators overestimated the levels of daylight illuminance required by occupants to work comfortably without overhead ambient electrical lighting. Time-lapse observation of interior roller shades showed that existing shade control models overestimated the frequency of shade operation and underestimated the level of facade occlusion due to interior shades. Comparison of measured results to the daylighting objectives of the SFFB showed that available daylight enabled electrical lighting energy reduction in the perimeter zones but not in the open-plan core zones. The results extend existing knowledge regarding the amount of daylight illuminance acceptable for occupants to work comfortably without overhead electrical lighting and for the physical variables (and stimulus intensities) associated with visual discomfort and the operation of interior shading devices.

}, keywords = {daylighting, performance assessment, San Francisco Federal Building, shading controls}, url = {https://escholarship.org/uc/item/7q35m7nq}, author = {Kyle S. Konis} } @booklet {1213, title = {Electro-Responsive Polymer Glazings For Smart Windows With Dynamic Daylighting Control}, year = {2012}, month = {02/2012}, abstract = {

In the context of alarming phenomenon of global warming with harmful consequences such as increased green house gases beyond predictions, the development of advanced energy efficient technologies became of a primary importance. Since the building sector accounts for 39\% of total US primary energy consumption, fenestration can significantly contribute to lowering the energy use for heating, cooling, and lighting. An estimated 9\% reduction in total US building energy use, or 3.47 Q, could be attained by dynamic solar/thermal control and daylighting if these advanced optical technologies were adopted throughout the residential and commercial building sectors. In spite of the great research and engineering efforts in the fast growing area of smart windows, development of glazing devices able to provide efficient, durable, and inexpensive products for dynamic daylight control is in infancy. Like the electrochromic glazings now emerging on the market, microscale, switchable daylight-redirecting glazings have the potential for widespread application if a low-cost, durable coating can be engineered and manufactured with the proper set of attributes.

Here we report on the development of a new technology using smart materials for switchable daylight-redirecting glazings. The proposed system consists in a prismatic optical element (POE) fabricated by micro-imprinting of an elastic redox-active polymer network capable to change its geometry and thereby its optical properties in response to an external stimulus. It is expected that the prismatic optical element reversibly collapses in response to an applied potential, thereby modulating the fraction of light which is redirected. The fabrication of the dynamic prismatic optical element from simulation-driven design to materials synthesis and device integration will be described. Investigation of specto-electrochemical characteristics of the redox-active grating and challenges encountered with respect to electromechanical induced structural changes will be also presented.

}, author = {Georgeta Masson and Rueben Mendlesberg and Irene Fernandez-Cuesta and Stefano Cabrini and Delia J. Milliron and Brett A. Helms and Eleanor S. Lee and Andrew McNeil and Stephen E. Selkowitz} } @article {55431, title = {End User Impacts of Automated Electrochromic Windows in a Pilot Retrofit Application}, journal = {Energy and Buildings}, volume = {47}, year = {2012}, month = {04/2012}, pages = {267-284}, chapter = {267}, abstract = {

Automated electrochromic (EC) windows, advanced thermally-improved window frames, and a dimmable lighting system were installed in a single, west-facing conference room in Washington DC. The EC windows were commercially-available, tungsten-oxide switchable devices, modulated automatically between either fully clear or fully tinted transparent states to control solar gains, daylight, and discomfort glare. Occupants were permitted to manually override the automated EC controls. The system was monitored over a 15-month period under normal occupied conditions. The last six months were used in the analysis. Manual override data were analyzed to assess the EC control system design and user satisfaction with EC operations. Energy and comfort were evaluated using both monitored data and simulations.

Of the 328 meetings that occurred over the six month period, the automatic system was manually overridden on 14 or 4\% of the meetings for reasons other than demonstration purposes. When overridden, occupants appeared to have switched the individual zones with deliberation, using a combination of clear and tinted zones and the interior Venetian blinds to produce the desired interior environment. Monitored weekday lighting energy savings were 91\% compared to the existing lighting system, which was less efficient, had a higher illuminance setpoint, and no controls. Annual performance was estimated using EnergyPlus, where the existing condition met the ASHRAE 90.1-2007 prescriptive requirements except for a higher window U-value. Annual energy savings were 48\% while peak demand savings were 35\%.

}, keywords = {buildings energy efficiency, control systems, daylighting, Electrochromic windows, Integrated systems, Intelligent buildings}, doi = {10.1016/j.enbuild.2011.12.003}, author = {Eleanor S. Lee and Erin S. Claybaugh and Marc LaFrance} } @article {11869, title = {Fenestration of Today and Tomorrow: A State-of-the-Art Review and Future Research Opportunities}, journal = {Solar Energy Materials and Solar Cells}, volume = {96}, number = {2012}, year = {2012}, month = {01/2012}, pages = {1-28}, chapter = {1}, abstract = {

Fenestration of today is continuously being developed into the fenestration of tomorrow, hence offering a steadily increase of daylight and solar energy utilization and control, and at the same time providing a necessary climate screen with a satisfactory thermal comfort. Within this work a state of the art market review of the best performing fenestration products has been carried out, along with an overview of possible future research opportunities for the fenestration industry. The focus of the market review was low thermal transmittance (U-value). The lowest centre of glass Ug-values found was 0.28 W/(m2K) and 0.30 W/(m2K), which was from a suspended coating glazing product and an aerogel glazing product, respectively. However, the majority of high performance products found were triple glazed. The lowest frame U-value was 0.61 W/(m2K). Vacuum glazing, smart windows, solar cell glazing, window frames, self cleaning glazing, low-emissivity coatings and spacers were also reviewed, thus also representing possibilities for controlling and harvesting the solar radiation energy. Currently, vacuum glazing, new spacer materials and solutions, electrochromic windows and aerogel glazing seem to have the largest potential for improving the thermal performance and daylight and solar properties in fenestration products. Aerogel glazing has the lowest potential U-values, ~ 0.1 W/(m2K), but requires further work to improve the visible transmittance. Electrochromic vaccum glazing and evacuated aerogel glazing are two vacuum related solutions which have a large potential. There may also be opportunities for completely new material innovations which could revolutionize the fenestration industry.

}, keywords = {Fenestration, Low-e, Multilayer glazing, Smart window, Solar cell glazing, Vacuum glazing}, doi = {10.1016/j.solmat.2011.08.010}, author = {Bj{\o}rn Petter Jelle and Andrew Hynd and Arlid Gustavsen and Dariush K. Arasteh and Howdy Goudey and Robert Hart} } @article {2964, title = {An Hourly-Based Performance Comparison of an Integrated Micro-Structural Perforated Shading Screen with Standard Shading Systems}, journal = {Energy and Buildings}, volume = {50}, year = {2012}, abstract = {

This article evaluates the performance of an integrated micro structural perforated shading screen (MSPSS). Such a system maintains a visual connection with the outdoors while imitating the shading functionality of a venetian blind. Building energy consumption is strongly influenced by the solar gains and heat transfer through the transparent parts of the fenestration systems. MSPSS is angular-dependent shading device that provides an effective strategy in the control of daylight, solar gains and overheating through windows. The study focuses on using direct experimental methods to determine bi-directional transmittance properties of shading systems that are not included as standard shading options in readily available building performance simulation tools. The impact on the indoor environment, particularly temperature and daylight were investigated and compared to three other static complex fenestration systems. The bi-directional description of the systems was used throughout the article. The simulations were validated against outdoor measurements of solar and light transmittance.

}, keywords = {building performance modelling, complex fenestration system, daylight, shading, solar gains}, doi = {10.1016/j.enbuild.2012.03.038}, author = {Appelfeld, David and Andrew McNeil and Svendsen, Svend} } @article {58917, title = {Improved structural and electrical properties of thin ZnO:Al films by dc filtered cathodic arc deposition}, journal = {Journal of Materials Research}, volume = {27}, year = {2012}, month = {3/2012}, pages = {857 - 862}, abstract = {

Transparent conducting oxide films are usually several 100-nm thick to achieve the required low sheet resistance. In this study, we show that the filtered cathodic arc technique produces high-quality low-cost ZnO:Al material for comparably smaller thicknesses than achieved by magnetron sputtering, making arc deposition a promising choice for applications requiring films less than 100-nm thick. A mean surface roughness less than 1 nm is observed for ZnO:Al films less than 100-nm thick, and 35-nm-thick ZnO:Al films exhibit Hall mobility of 28 cm2/Vs and a low resistivity of 6.5 {\texttimes} 10-4 Ωcm. Resistivity as low as 5.2 {\texttimes} 10-4 Ωcm and mobility as high as 43.5 cm2/Vs are obtained for 135-nm films.

}, keywords = {physical vapor deposition, Plasma deposition, Transparent conductor}, issn = {0884-2914}, doi = {10.1557/jmr.2011.342}, author = {Yuankun Zhu and Rueben J. Mendelsberg and Sunnie H.N. Lim and Jiaqi Zhu and Jiecai Han and Andr{\'e} Anders} } @techreport {58289, title = {Integrated control of operable fenestration systems and thermally massive HVAC systems: Methods and simulation studies of energy savings potential}, year = {2012}, month = {10/2012}, type = {DOE/ CEC PIER Technical Report}, abstract = {

The future design of high performance buildings is expected to involve more active facade technologies, acting in intelligent collaboration with the HVAC and lighting systems to produce comfortable indoor environments with reduced energy consumption. Integrated control of active facade systems and HVAC is challenging, particularly with thermally-massive HVAC systems such as radiant floors and ceilings. This paper describes methods for devising near-optimal controllers for such integrated systems, allowing for any arbitrary level of complexity in the facade system. An offline-optimization approximation to model predictive control is used with a model consisting of a reduced- order approximation of the zone and HVAC thermal properties and an interpolation grid of the daylight and solar gains attributes of the facade in its various possible states. The optimization over the 24-hour prediction horizon is split into two levels, with GenOpt used at the top level to deal with the complexity of the facade, alongside a linear programming solution to the chilled slab control. The model can be calibrated to match monitored data, or some combination of whole-building energy modeling and Radiance outputs. To test the methods and to estimate energy savings potential, case studies were performed with a calibrated model based on an EnergyPlus ASHRAE 90.1-2010 office building, modi ed to use radiant slabs and operable Venetian blinds (either internal or external) or electochromic glazing. Results are shown for four US climates. Further research is discussed.

}, author = {Brian E. Coffey} } @techreport {3419, title = {A Practical Framework for Sharing and Rendering Real-World Bidirectional Scattering Distribution Functions}, year = {2012}, month = {10/2012}, abstract = {

The utilization of real-world materials has been hindered by a lack of standards for sharing and interpreting measured data. This paper presents an XML representation and an Open Source C library to support bidirectional scattering distribution functions (BSDFs) in data-driven lighting simulation and rendering applications.The library provides for the efficient representation, query, and Monte Carlo sampling of arbitrary BSDFs in amodel-free framework. Currently, we support two BSDF data representations: one using a fixed subdivision of thehemisphere, and one with adaptive density. The fixed type has advantages for certain matrix operations, while theadaptive type can more accurately represent highly peaked data. We discuss advanced methods for data-driven BSDF rendering for both types, including the proxy of detailed geometry to enhance appearance and accuracy. We also present an advanced interpolation method to reduce measured data into these standard representations. We end with our plan for future extensions and sharing of BSDF data.

}, keywords = {building technology and urban systems department, windows and envelope materials group}, author = {Gregory J. Ward and Murat Kurt and Nicolas Bonneel} } @article {58922, title = {The {\textquoteleft}recycling trap{\textquoteright}: a generalized explanation of discharge runaway in high-power impulse magnetron sputtering}, journal = {Journal of Physics D: Applied Physics}, volume = {45}, year = {2012}, month = {01/2012}, pages = {012003}, abstract = {

Contrary to paradigm, magnetron discharge runaway cannot always be related to self-sputtering. We report here that the high density discharge can be observed with all conducting targets, including low sputter yield materials such as carbon. Runaway to a high density discharge is therefore generally based on self-sputtering in conjunction with the recycling of gas atoms in the magnetic field-affected pre-sheath. A generalized runaway condition can be formulated, offering a pathway to a time-dependent model for high-power impulse magnetron sputtering that includes rarefaction and an explanation for the termination of runaway.

}, issn = {0022-3727}, doi = {10.1088/0022-3727/45/1/012003}, author = {Andr{\'e} Anders and Ji{\v r}{\'\i} {\v C}apek and Mat{\^e}j H{\'a}la and Ludvik Martinu} } @techreport {1214, title = {Using Radiance and GenOpt to design static daylight redirection systems}, year = {2012}, month = {09/2012}, type = {DOE/ CEC PIER Technical Report}, author = {Andrew McNeil and Eleanor S. Lee} } @article {3184, title = {A validation of the Radiance three-phase simulation method for modeling annual daylight performance of optically-complex fenestration systems}, journal = {Journal of Building Performance Simulation}, volume = {April 2012}, year = {2012}, month = {05/2012}, keywords = {bidirectional scattering distribution functions, buildings energy efficiency, daylighting, radiance, validation}, doi = {10.1080/19401493.2012.671852}, author = {Andrew McNeil and Eleanor S. Lee} } @techreport {3182, title = {Validation of the Window Model of the Modelica Buildings Library}, year = {2012}, month = {07/2012}, abstract = {

This paper describes the validation of the window model of the free open-source Modelica Buildings library. This paper starts by describing the physical modeling assumptions of the window model. The window model can be used to calculate the thermal and angular properties of glazing systems. It can also be used for steady-state simulation of heat transfer mechanism in glazing systems. We present simulation results obtained by comparing the window model with WINDOW 6 the well established simulation tool for steady-state heat transfer in glazing systems. We also present results obtained by comparing the window model with measurements carried out in a test cell at the Lawrence Berkeley National Laboratory.

}, author = {Thierry Stephane Nouidui and Michael Wetter and Wangda Zuo} } @conference {3385, title = {Acceleration of Radiance for Lighting Simulation by using Parallel Computing with OpenCL}, booktitle = {12th International Conference of the International Building Performance Simulation Association (Building Simulation 2011)}, year = {2011}, month = {11/2011}, pages = {p. 110-117}, address = {Sydney, Australia}, abstract = {

This study attempted to accelerate annual daylighting simulations for fenestration systems in Radiance ray-tracing program. The algorithm was optimized to reduce both the redundant data input/output operations and floating-point operations. To further accelerate the simulation speed, calculation for matrices multiplications was implemented in parallel on a graphics processing unit using OpenCL, a cross-platform parallel programming language. Numerical experiments show that combination of above measures can speed up the annual daylighting simulations 101.7 times or 28.6 times when sky vector has 146 or 2306 elements, respectively.

}, author = {Wangda Zuo and Andrew McNeil and Michael Wetter and Eleanor S. Lee} } @article {2974, title = {Achieving high mobility ZnO:Al at very high growth rates by dc filtered cathodic arc deposition}, journal = {Journal of Physics D: Applied Physics}, volume = {44}, year = {2011}, pages = {232003-232007}, chapter = {232003}, abstract = {

Achieving a high growth rate is paramount for making large-area transparent conducting oxide coatings at a low cost. Unfortunately, the quality of thin films grown by most techniques degrades as the growth rate increases. Filtered dc cathodic arc is a lesser known technique which produces a stream of highly ionized plasma, in stark contrast to the neutral atoms produced by standard sputter sources. Ions bring a large amount of potential energy to the growing surface which is in the form of heat, not momentum. By minimizing the distance from cathode to substrate, the high ion flux gives a very high effective growth temperature near the film surface without causing damage from bombardment. The high surface temperature is a direct consequence of the high growth rate and allows for high-quality crystal growth. Using this technique, 500{\textendash}1300\ nm thick and highly transparent ZnO\ :\ Al films were grown on glass at rates exceeding 250\ nm\ min-1 while maintaining resistivity below 5 {\texttimes} 10-4\ Ω\ cm with electron mobility as high as 60\ cm2\ V-1\ s-1.

}, doi = {10.1088/0022-3727/44/23/232003}, author = {Rueben J. Mendelsberg and Sunnie H.N. Lim and Yuankun Zhu and Joe Wallig and Delia J. Milliron and Andr{\'e} Anders} } @conference {1174, title = {COMFEN 3.0: Evolution of an Early Design Tool for Commercial Fa{\c c}ades and Fenestration Systems}, booktitle = {Building Enclosure Sustainability Symposium (BESS), April 29-30, 2011}, year = {2011}, month = {03/2011}, address = {Pomona, CA}, abstract = {

Achieving a net-zero energy building cannot be done solely by improving the efficiency of the engineering systems. It also requires consideration of the essential nature of the building including factors such as architectural form, massing, orientation and enclosure. Making informed decisions about the fundamental character of a building requires assessment of the effects of the complex interaction of these factors on the resulting performance of the building. The complexity of these interactions necessitates the use of modeling and simulation tools to dynamically analyze the effects of the relationships, yet decisions about the building fundamentals are often made in the earliest stages of design, before a {\textquoteright}building{\textquoteright} exists to model.

To address these issues, Lawrence Berkeley National Laboratory (LBNL) has developed an early-design energy modeling tool (COMFEN) specifically to help make informed decisions about building fa{\c c}ade fundamentals by considering the design of the building envelope, orientation and massing on building performance. COMFEN focuses on the concept of a "space" or "room" and uses the EnergyPlus, and Radiance{\texttrademark} engines and a simple, graphic user interface to allow the user to explore the effects of changing key early-design input variables on energy consumption, peak energy demand, and thermal and visual comfort. Comparative results are rapidly presented in a variety of graphic and tabular formats to help users move toward optimal fa{\c c}ade and fenestration design choices.

While COMFEN 1.0 utilized an Excel{\texttrademark}{\textendash}based user interface, COMFEN 3.0 has been reworked to include a simple, more intuitive, yet powerful Graphic User Interface (GUI), a broader range of libraries for associated system and component choices and deliver a wider range of graphic outputs and options.

This paper (and presentation) outlines the objectives in developing and further refining COMFEN, the mechanics of the program, and plans for future development.\ 

}, author = {Stephen E. Selkowitz and Robin Mitchell and Maurya McClintock and Daniel McQuillen and Andrew McNeil and Mehry Yazdanian} } @techreport {1215, title = {Computing and applying variable-resolution data for bidirectional scattering distribution functions}, year = {2011}, month = {09/2011}, type = {DOE Technical Report}, abstract = {

We introduce the Tensor Tree representation for bidirectional scattering distribution functions (BSDFs), a variable-resolution data structure designed to minimize storage and computation. We offer a method for reducing full-resolution BSDF data into this format, and relate techniques for the efficient generation of uniformly weighted Monte Carlo samples. The Tensor Tree BSDF representation has been tested and incorporated into the 4.1 release of LBNL{\textquoteright}s Radiance lighting simulation and rendering system, with additional methods for modeling the appearance of complex fenestration systems. Finally, an independent software library is described for third-party developers who wish to support BSDF data outside of Radiance, and recommendations are made for future development directions.

}, author = {Gregory J. Ward} } @conference {58301, title = {Co-simulation based building controls implementation with networked sensors and actuators}, booktitle = {Third ACM Workshop on Embedded Sensing Systems for Energy-Efficiency in Buildings}, volume = {Proceedings of BuildSys 2011}, year = {2011}, month = {11/2011}, pages = {55}, publisher = {ACM Press}, organization = {ACM Press}, address = {Seattle, Washington}, abstract = {

The commercial building sector is one of the largest energy consumers in the U.S., and lighting, heating, ventilating and air conditioning contribute to more than half of the energy consumption and carbon emissions in buildings. Controls are the most effective way of increasing energy efficiency in building systems; however, the interdependencies among building subsystems must be taken into account to achieve deep energy savings. A networked sensing and actuation infrastructure shared among building systems is the key to optimal integrated control of the interdependent building elements in low energy and zero net energy buildings.

This paper presents a rapid-prototyping controls implementation platform based on the Building Controls Virtual Test Bed (BCVTB) framework that is capable of linking to building sensor and actuator networks for efficient controller design and testing. The platform creates a separation between the controls and the physical systems so that the controller can easily be implemented, tested and tuned with real performance feedback from a physical implementation. We realized an integrated lighting control algorithm using such a rapid-prototyping platform in a testing facility with networked sensors and actuators. This implementation has demonstrated an up to 57\% savings in lighting electricity and 28\% reduction in cooling demand.

}, isbn = {9781450307499}, doi = {10.1145/2434020.2434040}, author = {Yao-Jung Wen and Dennis L. DiBartolomeo and Francis M. Rubinstein} } @article {58919, title = {Dynamically Modulating the Surface Plasmon Resonance of Doped Semiconductor Nanocrystals}, journal = {Nano Letters}, volume = {11}, year = {2011}, month = {10/2011}, pages = {4415 - 4420}, abstract = {

Localized surface plasmon absorption features arise at high doping levels in semiconductor nanocrystals, appearing in the near-infrared range. Here we show that the surface plasmons of tin-doped indium oxide nanocrystal films can be dynamically and reversibly tuned by postsynthetic electrochemical modulation of the electron concentration. Without ion intercalation and the associated material degradation, we induce a \> 1200 nm shift in the plasmon wavelength and a factor of nearly three change in the carrier density.

}, keywords = {doping, indium tin oxide, nanocrystal, spectroelectrochemistry, surface plasmon}, issn = {1530-6984}, doi = {10.1021/nl202597n}, author = {Guillermo Garcia and Raffaella Buonsanti and Evan L. Runnerstrom and Rueben J. Mendelsberg and Anna Llordes and Andr{\'e} Anders and Thomas J. Richardson and Delia J. Milliron} } @book {58278, title = {GenOpt Generic Optimization Program, User Manual, Version 3.1.0}, year = {2011}, month = {12/2011}, publisher = {Simulation Research Group, Lawrence Berkeley National Laboratory}, organization = {Simulation Research Group, Lawrence Berkeley National Laboratory}, address = {Berkeley}, abstract = {

GenOpt is an optimization program for the minimization of a cost function that is evaluated by an external simulation program. It has been developed for optimization problems where the cost function is computationally expensive and its derivatives are not available or may not even exist. GenOpt can be coupled to any simulation programthat reads its input from text files and writes its output to text files. The independent variables can be continuous variables (possibly with lower and upper bounds), discrete variables, or both, continuous and discrete variables. Constraints on dependent variables can be implemented using penalty or barrier functions. GenOpt uses parallel computing to evaluate the simulations. GenOpt has a library with local and global multi-dimensional and one-dimensional optimization algorithms, and algorithms for doing parametric runs. An algorithm interface allows adding new minimization algorithms without knowing the details of the program structure. GenOpt is written in Java so that it is platform independent. The platform independence and the general interface make GenOpt applicable to a wide range of optimization problems. GenOpt has not been designed for linear programming problems, quadratic programming problems, and problems where the gradient of the cost function is available. For such problems, as well as for other problems, special tailored software exists that is more efficient.

}, author = {Michael Wetter} } @article {12005, title = {Key Elements of and Materials Performance Targets for Highly Insulating Window Frames}, journal = {Energy and Buildings}, volume = {43}, number = {10}, year = {2011}, month = {10/2011}, pages = {2583-2594}, chapter = {2583}, abstract = {

The thermal performance of windows is important for energy efficient buildings. Windows typically account for about 30{\textendash}50 percent of the transmission losses though the building envelope, even if their area fraction of the envelope is far less. The reason for this can be found by comparing the thermal transmittance (U-factor) of windows to the U-factor of their opaque counterparts (wall, roof and floor constructions). In well insulated buildings the U-factor of walls, roofs and floors can be between 0.1 and 0.2 W/(m2 K). The best windows have U-factors of about 0.7{\textendash}1.0. It is therefore obvious that the U-factor of windows needs to be reduced, even though looking at the whole energy balance for windows (i.e., solar gains minus transmission losses) makes the picture more complex.

In high performance windows the frame design and material use are of utmost importance, as the frame performance is usually the limiting factor for reducing the total window U-factor further. This paper describes simulation studies analyzing the effects on frame and edge-of-glass U-factors of different surface emissivities as well as frame material and spacer conductivities. The goal of this work is to define material research targets for window frame components that will result in better frame thermal performance than is exhibited by the best products available on the market today.

}, keywords = {Fenestration, heat transfer modeling, thermal performance, thermal transmittance, u-factor, window frames}, doi = {10.1016/j.enbuild.2011.05.010}, author = {Arlid Gustavsen and Steinar Grynning and Dariush K. Arasteh and Bj{\o}rn Petter Jelle and Howdy Goudey} } @techreport {58299, title = {Model-based controls for integrated shading and UFAD control: Report on initial studies}, year = {2011}, month = {10/2011}, type = {DOE/ CEC PIER Technical Report}, abstract = {

Methods and initial results are described for model-based controls with offline optimization for integrated shading and UFAD control for an office building in New York. Two cases are studied through lookup-table calculation and annual simulation of the resulting controllers: one case with interior blinds, the other case with exterior blinds. The interior blind case was found to reduce HVAC energy by 5\% over a simple baseline control, and the exterior blind case produced a 5.6\% HVAC energy savings over the baseline. Further investigations and case studies are planned.

}, keywords = {cloud computing, integrated controls, Model predictive control (MPC), offline optimization, shading and HVAC controls}, author = {Brian E. Coffey and Eleanor S. Lee} } @techreport {58281, title = {Modeling solar heat gains of complex fenestration systems using bidirectional scattering distribution functions}, year = {2011}, month = {09/2011}, type = {DOE/ CEC PIER Technical Report}, author = {Thierry Stephane Nouidui and Andrew McNeil and Christian Kohler and Brian E. Coffey and Eleanor S. Lee} } @article {12172, title = {Performance of Integrated Systems of Automated Roller Shade Systems and Daylight Responsive Dimming Systems}, journal = {Building and Environment}, volume = {46}, year = {2011}, month = {03/2011}, pages = {747-757}, chapter = {747}, abstract = {

Daylight responsive dimming systems have been used in few buildings to date because they require improvements to improve reliability. The key underlying factor contributing to poor performance is the variability of the ratio of the photosensor signal to daylight workplane illuminance in accordance with sun position, sky condition, and fenestration condition. Therefore, this paper describes the integrated systems between automated roller shade systems and daylight responsive dimming systems with an improved closed-loop proportional control algorithm, and the relative performance of the integrated systems and single systems. The concept of the improved closed-loop proportional control algorithm for the integrated systems is to predict the varying correlation of photosensor signal to daylight workplane illuminance according to roller shade height and sky conditions for improvement of the system accuracy. In this study, the performance of the integrated systems with two improved closed-loop proportional control algorithms was compared with that of the current (modified) closed-loop proportional control algorithm. In the results, the average maintenance percentage and the average discrepancies of the target illuminance, as well as the average time under 90\% of target illuminance for the integrated systems significantly improved in comparison with the current closed-loop proportional control algorithm for daylight responsive dimming systems as a single system.

}, keywords = {automated roller shade systems, daylight responsive dimming systems, daylighting, Integrated systems, photoelectric controls}, doi = {10.1016/j.buildenv.2010.10.007}, author = {Byoung-Chul Park and An-Seop Choi and Jae-Weon Jeong and Eleanor S. Lee} } @article {58921, title = {A Plasma Lens for Magnetron Sputtering}, journal = {IEEE Transactions on Plasma Science}, volume = {39}, year = {2011}, month = {11/2011}, pages = {2528 - 2529}, abstract = {

A plasma lens, consisting of a solenoid and potential-defining ring electrodes, has been placed between a magnetron and substrates to be coated. Photography reveals qualitative information on excitation, ionization, and the transport of plasma to the substrate.

}, issn = {0093-3813}, doi = {10.1109/TPS.2011.2157172}, author = {Andr{\'e} Anders and Jeff Brown} } @techreport {1216, title = {Rapid Prototyping Control Implementation using the Building Controls Virtual Test Bed}, year = {2011}, month = {09/2011}, type = {Philips Technical Report}, abstract = {

This report documents the development of a rapid-prototyping control framework based on the Building Controls Virtual Test Bed co-simulation software. The objective of the developed framework is to establish the separation between the control algorithm and the physical systems such that the control algorithm can be rapidly revised and implemented without having to physically swap the controllers. The corresponding protocols and interfaces are designed for maximal flexibility, easy generalization and straightforward implementation. An instance of such control framework has been realized in the Advanced Windows Testing Facility at the Lawrence Berkeley National Laboratory and is used as a case study throughout this report.

}, author = {Yao-Jung Wen} } @techreport {1217, title = {On the sensitivity of daylight simulations to the resolution of the hemispherical basis used to define bidirectional scattering distribution functions}, year = {2011}, month = {09/2011}, pages = {19}, type = {DOE / CEC PIER Technical Memorandum}, abstract = {

The Radiance simulation program includes new tools that enable daylight modeling of complex fenestration systems (CFS) using bi-directional transmission distribution functions (BTDF). The tools use the Klems angle basis to define the number of paired incoming and outgoing data values. However, the Klems angle basis was developed for thermal simulations and may be too low of a resolution for some types of daylight systems, particularly those that exhibit peaky, specular transmission. This study evaluates the sensitivity of the angle basis resolution by comparing simulation results for the Klems angle basis against results using two higher resolution angle bases. The first evaluation compares results for specific points in time. The second evaluation compares simulation results using annual performance metrics. Annual lighting energy data were found to agree to within 1\%. Annual assessments of discomfort glare were found to disagree by 7\% because high resolution basis resolved glare sources into smaller, more intense sources. We concluded that high resolution bases are appropriate for specific types of CFS and performance metrics.

}, author = {Andrew McNeil} } @article {1799, title = {Simulating the Daylight Performance of Complex Fenestration Systems Using Bidirectional Scattering Distribution Functions within Radiance}, journal = {Leukos, The Journal of the Illuminating Engineering Society}, volume = {7}, year = {2011}, month = {04/2011}, chapter = {241}, abstract = {

We describe two methods which rely on bidirectional scattering distribution functions (BSDFs) to model the daylighting performance of complex fenestration systems (CFS), enabling greater flexibility and accuracy in evaluating arbitrary assemblies of glazing, shading, and other optically-complex coplanar window systems. Two tools within Radiance enable a) efficient annual performance evaluations of CFS, and b) accurate renderings of CFS despite the loss of spatial resolution associated with low-resolution BSDF datasets for inhomogeneous systems. Validation, accuracy, and limitations of the methods are discussed.

}, keywords = {bidirectional scattering distribution function (BSDF), Complex fenestration systems, daylighting systems, energy, Radiance software, Shading Systems, windows}, issn = {1550-2724}, doi = {10.1080/15502724.2011.10732150}, author = {Gregory J. Ward and Richard G. Mistrick and Eleanor S. Lee and Andrew McNeil and Jacob C. Jonsson} } @techreport {1218, title = {Using Helmholtz reciprocity in variable resolution BSDFs in Radiance}, year = {2011}, month = {11/2011}, institution = {Bartenbach L-chtLabor}, author = {David Geisler-Moroder} } @techreport {1219, title = {Validation of variable resolution BSDFs in Radiance}, year = {2011}, month = {11/2011}, institution = {Bartenbach L-chtLabor}, abstract = {

In this document results of the validation of the "Variable Resolution BSDF" approach as presented at the 10th International Radiance Workshop (G.Ward, A.McNeil, "A Variable-resolution BSDF Implementation") are presented.

Variable-resolution BSDFs are generated with genBSDF for the RADIANCE native materials plastic, trans, and glass (isotropic) and plastic2 and trans2 (anisotropic). Both, the maximum resolution (1024 x 1024 patches or 4096 x 4096 patches) as well as the number of specular samples (16 or 64) are varied.

The resulting data is reduced with rttree_reduce at various degrees (0\%, i.e. no reduction, 95\%, i.e. reduction by approximately 95\%, and 99\%, i.e. only about 1\% of data left).

}, author = {David Geisler-Moroder} } @article {1957, title = {Visual Comfort Analysis of Innovative Interior and Exterior Shading Systems for Commercial Buildings using High Resolution Luminance Images}, journal = {LEUKOS The Journal of the Illuminating Engineering Society of North America}, volume = {7}, year = {2011}, month = {1/2011}, abstract = {

The objective of this study was to explore how calibrated high dynamic range (HDR) images (luminance maps) acquired in real world daylit environments can be used to characterize, evaluate, and compare visual comfort conditions of innovative facade shading and light-redirecting systems. Detailed (1536 x 1536 pixel) luminance maps were time-lapse acquired from two view positions in an unoccupied full scale testbed facility. These maps were analyzed using existing visual comfort metrics to quantify how innovative interior and exterior shading systems compare to conventional systems under real sun and sky conditions over a solstice-to-solstice test interval. The results provide a case study in the challenges and potential of methods of visualizing, evaluating and summarizing daily and seasonal variation of visual comfort conditions computed from large sets of image data.

}, doi = {10.1582/LEUKOS.2011.07.03003}, author = {Kyle S. Konis and Eleanor S. Lee and Robert D. Clear} } @conference {1408, title = {Experimental and Numerical Examination of the Thermal Transmittance of High Performance Window Frames}, booktitle = {Thermal Performance of the Exterior Envelopes of Whole Buildings XI International Conference, December 5-9, 2010}, year = {2010}, month = {09/2010}, address = {Clearwater Beach, FL}, abstract = {

While window frames typically represent 20-30\% of the overall window area, their impact on the total window heat transfer rates may be much larger. This effect is even greater in low-conductance (highly insulating) windows which incorporate very low conductance glazings. Developing low-conductance window frames requires accurate simulation tools for product research and development.

The Passivhaus Institute in Germany states that windows (glazing and frames, combined) should have U-values not exceeding 0.80 W/(m2 K). This has created a niche market for highly insulating frames, with frame U-values typically around 0.7-1.0 W/(m2 K). The U-values reported are often based on numerical simulations according to international simulation standards. It is prudent to check the accuracy of these calculation standards, especially for high performance products before more manufacturers begin to use them to improve other product offerings.

In this paper the thermal transmittance of five highly insulating window frames (three wooden frames, one aluminum frame and one PVC frame), found from numerical simulations and experiments, are compared. Hot box calorimeter results are compared with numerical simulations according to ISO 10077-2 and ISO 15099. In addition CFD simulations have been carried out, in order to use the most accurate tool available to investigate the convection and radiation effects inside the frame cavities.

Our results show that available tools commonly used to evaluate window performance, based on ISO standards, give good overall agreement, but specific areas need improvement.

}, keywords = {experimental, Fenestration, frame cavity, heat transfer modeling, hot box, international standards, thermal transmittance, U-value, window frames}, author = {Arlid Gustavsen and Goce Talev and Dariush K. Arasteh and Howdy Goudey and Christian Kohler and Sivert Uvsl{\o}kk and Bj{\o}rn Petter Jelle} } @article {58219, title = {Light-scattering properties of a Venetian blind slat used for daylighting applications}, journal = {Solar Energy}, volume = {84}, year = {2010}, month = {12/2010}, pages = {2103 - 2111}, abstract = {

The low cost, simplicity, and aesthetic appearance of external and internal shading devices, make them commonly used for daylighting and glare-control applications. Shading devices, such as Venetian blinds, screens, and roller shades, generally exhibit light scattering and/or light redirecting properties. This requires the bi-directional scattering distribution function (BSDF) of the material to be known in order to accurately predict the daylight distribution and energy flow through the fenestration system. Acquiring the complete BSDF is not a straightforward task, and to complete the process it is often required that a model is used to complement the measured data. In this project, a Venetian blind slat with a white top surface and a brushed aluminum bottom surface was optically characterized. A goniophotometer and an integrating sphere spectrophotometer were used to determine the angle resolved and hemispherical reflectance of the sample, respectively. The acquired data were fitted to a scattering model providing one Lambertian and one angle dependent description of the surface properties. These were used in combination with raytracing to obtain the complete BSDFs of the Venetian blind system.

}, keywords = {ABg-model, BSDF, Raytracing, Venetian blinds}, issn = {0038092X}, doi = {10.1016/j.solener.2010.09.005}, author = {Annica M. Nilsson and Jacob C. Jonsson} } @techreport {58302, title = {Post Occupancy Study of The New York Times Building: Survey Findings Assessing Occupant Comfort and Satisfaction}, year = {2010}, month = {11/2010}, type = {Final report by Sustainable Energy Partnerships}, address = {Tarrytown, New York}, abstract = {

The New York Times (NY Times) building located at 620 Eighth Avenue in Manhattan was designed to include state of the art, environmentally-sustainable features intended to enhance occupant satisfaction and save energy. Some of the features in the NY Times space, including daylight dimming controls, automated window shades, and an advanced under-floor air distribution (UFAD) system, were first of their kind ventures on this scale in the US. The New York State Energy Research \& Development Authority (NYSERDA) actively supported the design and construction of this new facility with significant incentives toward the innovative features of the facility.

In order to understand occupant satisfaction and comfort levels associated with these new technologies, NYSERDA is providing support to the NY Times Facility Management staff with a simplified post occupancy review, assisting with development and analysis of an occupant satisfaction survey. The survey (survey instrument attached as Appendix 2) was intended to determine the level of occupant satisfaction with certain aspects of the indoor environmental quality of the NY Times Building, with a special focus on lighting and comfort quality provided by the innovative lighting/shading control and UFAD systems. In distributing the survey, it was stated that results from the survey would be shared with occupants, and will also inform Facilities Management in their operation of the building.

}, author = {Adam Hinge} } @techreport {58235, title = {Post-Occupancy Evaluation of The New York Times Headquarters Building: an Examination of Causes for Occupant Satisfaction and Dissatisfaction with the Energy-Efficiency Measures}, year = {2010}, month = {10/2010}, type = {DOE/LBNL Technical report}, address = {Berkeley}, abstract = {

A post-occupancy evaluation (POE) survey was issued by The New York Times (NYT) to their employees with the assistance of Sustainable Energy Partnerships (SEP). SEP conducted a detailed analysis of the survey data (September 29, 2010 draft) and found that a significant fraction of the building occupants were satisfied to very satisfied with the overall building. Compared to other buildings, the overall level of satisfaction was greater than the norm of surveyed buildings.

This additional analysis was conducted to identify potential causes of the occupants{\textquoteright} satisfaction or dissatisfaction with the innovative lighting, shading, and space- conditioning systems themselves and/or the resultant indoor environment produced by these systems. The analysis used various methods to identify statistically significant factors, where the factors were those given in the survey questionnaire. Additional factors or causes of satisfaction and dissatisfaction were identified through analysis of the detailed comments: this was done for the questions related to the lighting section of the survey.

}, author = {Robert D. Clear} } @conference {1807, title = {Singapore{\textquoteright}s Zero-Energy Building{\textquoteright}s Daylight Monitoring System}, booktitle = {International Conference on Applied Energy 2010: Energy Solutions for a Sustainable World}, year = {2010}, month = {04/2010}, address = {Singapore}, abstract = {

A setup to monitor the daylighting performance of different glazing types in Singapore is presented. The glazing is installed in the facade of four dedicated testing chambers in BCAA{\textquoteright}s Zero Energy Building in Singapore. These test rooms are equipped with sensors that both record illuminances on the work plane, and luminances as seen by occupants. The physical and logical design of the monitoring system is presented. Criteria to assess the daylighting performance are introduced, and initial results of the work in progress are presented.

}, author = {Stephen E. Selkowitz} } @article {1869, title = {Supersonic metal plasma impact on a surface: an optical investigation of the pre-surface region}, journal = {Journal of Physics D: Applied Physics}, volume = {43}, year = {2010}, month = {04/2010}, chapter = {135201}, abstract = {

Aluminum plasma, produced in high vacuum by a pulsed, filtered cathodic arc plasma source, was directed onto a wall where if formed a coating. The accompanying "optical flare" known from the literature was visually observed, photographed, and spectroscopically investigated with appropriately high temporal (1 μs) and spatial (100 μm) resolution. Consistent with other observations using different techniques, it was found that the impact of the fully ionized plasma produces metal neutrals as well as desorbed gases, both of which interact with the incoming plasma. Most effectively are charge exchange collisions between doubly charged aluminum and neutral aluminum, which lead to a reduction of the flow of doubly charged before they reach the wall, and a reduction of neutrals as the move away from the surface. Those plasma-wall interactions are relevant for coating processes as well as for interpreting the plasma properties such as ion charge state distributions.

}, keywords = {cathodic arc plasma, ions, neutrals, optical emission spectroscopy, plasma-wall interaction}, doi = {10.1088/0022-3727/43/13/135201}, author = {Pavel A Ni and Andr{\'e} Anders} } @article {11677, title = {Daylight metrics and energy savings}, journal = {Lighting Research + Technology}, volume = {41}, year = {2009}, month = {09/2009}, pages = {261-283}, chapter = {261}, abstract = {

The drive towards sustainable, low-energy buildings has increased the need for simple, yet accurate methods to evaluate whether a "daylit" building meets minimum standards for energy and human comfort performance. Current metrics do not account for the temporal and spatial aspects of daylight, nor of occupants comfort or interventions. This paper reviews the historical basis of current compliance methods for achieving daylit buildings, proposes a technical basis for development of better metrics, and provides two case study examples to stimulate dialogue on how metrics can be applied in a practical, real-world context.

}, doi = {10.1177/1477153509339703}, author = {John Mardaljevic and Lisa Heschong and Eleanor S. Lee} } @article {58228, title = {Field Measurements of Innovative Indoor Shading Systems in a Full-Scale Office Testbed}, journal = {ASHRAE Transactions}, volume = {115}, year = {2009}, month = {10/2009}, pages = {706-728}, chapter = {706}, abstract = {

The development of spectrally selective low-e glass with its superior solar control and high daylight admission has led to widespread use of large-area, "transparent" or visually clear glass windows in commercial building facades. This type of fa{\c c}ade can provide significant inherent daylighting potential (ability to offset lighting energy use) and move us closer to the goal of achieving zero energy buildings, if not for the unmitigated glare that results from the unshaded glazing. Conventional shading systems result in a significant loss of daylight and view. Can innovative shading solutions successfully balance the tradeoffs between daylight, solar heat gains, discomfort glare, and view?

To investigate this issue, a six-month solstice-to-solstice field study was conducted in a sunny climate to measure the thermal and daylighting performance of a south-facing, full- scale, office testbed with large-area windows and a variety of innovative indoor shading systems. Indoor shading systems included manually-operated and automated roller shades, Venetian blinds, daylight-redirecting blinds, and a static translucent diffusing panel placed inboard of the window glazing. These innovative systems were compared to a reference shade lowered to block direct sun.

With continuous dimming controls, all shading systems yielded lighting energy savings between 43-69\% compared to a non-dimming case, but only the automated systems were able to meet visual comfort criteria throughout the entire monitored period. Cooling loads due to solar and thermal loads from the window were increased by 2-10\% while peak cooling loads were decreased by up to 14\%. The results from this experiment illustrate that some indoor shading systems can preserve daylight potential while meeting comfort requirements. Trends will differ significantly depending on application.

}, author = {Eleanor S. Lee and Dennis L. DiBartolomeo and Joseph H. Klems and Robert D. Clear and Kyle S. Konis and Mehry Yazdanian and Byoung-Chul Park} } @techreport {1458, title = {High Performance Building Facade Solutions: PIER Final Project Report}, year = {2009}, month = {12/2009}, abstract = {

Building fa{\c c}ades directly influence heating and cooling loads and indirectly influence lighting loads when daylighting is considered, and are therefore a major determinant of annual energy use and peak electric demand. fa{\c c}ades also significantly influence occupant comfort and satisfaction, making the design optimization challenge more complex than many other building systems.

This work focused on addressing significant near-term opportunities to reduce energy use in California commercial building stock by a) targeting voluntary, design-based opportunities derived from the use of better design guidelines and tools, and b) developing and de ploying more efficient glazings, shading systems, daylighting systems, fa{\c c}ade systems and integrated controls.

This two-year project, supported by the California Energy Commission PIER program and the US Department of Energy, initiated a collaborative effort between The Lawrence Berkeley National Laboratory (LBNL) and major stakeholders in the fa{\c c}ades industry to develop, evaluate, and accelerate market deployment of emerging, high-performance, integrated fa{\c c}ade solutions. The LBNL Windows Testbed Facility acted as the primary cata lyst and mediator on both sides of the building industry supply-user business transaction by a) aiding component suppliers to create and optimize cost effective, integrated systems that work, and b) demonstrating and verifying to the owner, designer, and specifier community that these integrated systems reliably deliver required energy performance. An industry consortium was initiated amongst approximately seventy disparate stakeholders, who unlike the HVAC or lighting industry, has no single representative, multi-disciplinary body or organized means of communicating and collaborating. The consortium provided guidance on the project and more importantly, began to mutually work out and agree on the goals, criteria, and pathways needed to attain the ambitious net zero energy goals defined by California and the US.

A collaborative test, monitoring, and reporting protocol was also formulated via the Windows Testbed Facility in collaboration with industry partners, transitioning industry to focus on the import ance of expecting measured performance to consistently achieve design performance expectations. The facility enables accurate quantification of energy use, peak demand, and occupant comfort impacts of synergistic fa{\c c}ade-lighting-HVAC systems on an apples-to-apples comparative basis and its data can be used to verify results from simulations.

Emerging interior and exterior shading technologies were investigated as potential near-term, low-cost solutions with potential broad applicability in both new and retrofit construction. Commercially-available and prototype technologies were developed, tested, and evaluated. Full-scale, monitored field tests were conducted over solstice-to-solstice periods to thoroughly evaluate the technologies, uncover potential risks associated with an unknown, and quantify performance benefits. Exterior shading systems were found to yield net zero energy levels of performance in a sunny climate and significant reductions in summer peak demand. Automated interior shading systems were found to yield significant daylighting and comfort-related benefits.

In support of an integrated design process, a PC-based commercial fenestration (COMFEN) software package, based on EnergyPlus, was developed that enables architects and engineers to x quickly assess and compare the performance of innovative fa{\c c}ade technologies in the early sketch or schematic design phase. This tool is publicly available for free and will continue to improve in terms of features and accuracy. Other work was conducted to develop simulation tools to model the performance of any arbitrary complex fenestration system such as common Venetian blinds, fabric roller shades as well as more exotic innovative fa{\c c}ade systems such as optical louver systems.

The principle mode of technology transfer was to address the key market barriers associated with lack of information and facile simulation tools for early decisionmaking. The third party data generated by the field tests and simulation data provided by the COMFEN tool enables utilities to now move forward toward incentivizing these technologies in the marketplace.

}, author = {Eleanor S. Lee and Stephen E. Selkowitz and Dennis L. DiBartolomeo and Joseph H. Klems and Robert D. Clear and Kyle S. Konis and Robert J. Hitchcock and Mehry Yazdanian and Robin Mitchell and Maria Konstantoglou} } @article {11918, title = {High quality ZnO:Al transparent conducting oxide films synthesized by pulsed filtered cathodic arc deposition}, journal = {Thin Solid Films}, year = {2009}, abstract = {

Aluminum-doped zinc oxide, ZnO:Al or AZO, is a well-known n-type transparent conducting oxide with great potential in a number of applications currently dominated by indium tin oxide (ITO). In this study, the optical and electrical properties of AZO thin films deposited on glass and silicon by pulsed filtered cathodic arc deposition are systematically studied. In contrast to magnetron sputtering, this technique does not produce energetic negative ions, and therefore ion damage can be minimized. The quality of the AZO films strongly depends on the growth temperature while only marginal improvements are obtained with post-deposition annealing. The best films, grown at a temperature of about 200{\textdegree}C, have resistivities in the low to mid 10-4Ω cm range with a transmittance better than 85\% in the visible part of the spectrum. It is remarkable that relatively good films of small thickness (60 nm) can be fabricated using this method.

}, author = {Andr{\'e} Anders and Sunnie H.N. Lim and Kin Man Yu and Joakim Andersson and Johanna Ros{\'e}n and Mike McFarland and Jeff Brown} } @article {58915, title = {Innovative Fa{\c c}ade Systems for Low-energy Commercial Buildings}, year = {2009}, month = {11/2009}, publisher = {Lawrence Berkeley National Laboratory}, address = {Berkeley}, abstract = {

Glazing and fa{\c c}ade systems have very large impacts on all aspects of commercial building performance. They directly influence peak heating and cooling loads, and indirectly influence lighting loads when daylighting is considered. In addition to being a major determinant of annual energy use, they can have significant impacts on peak cooling system sizing, electric load shape, and peak electric demand. Because they are prominent architectural and design elements and because they influence occupant preference, satisfaction and comfort, the design optimization challenge is more complex than with many other building systems.

Fa{\c c}ade designs that deliberately recognize the fundamental synergistic relationships between the fa{\c c}ade, lighting, and mechanical systems have the potential to deliver high performance over the life of the building. These "integrated" fa{\c c}ade systems represent a key opportunity for commercial buildings to significantly reduce energy and demand, helping to move us toward our goal of net zero energy buildings by 2030.

Provision of information {\textemdash} technology concepts, measured data, case study information, simulation tools, etc. {\textemdash} can enable architects and engineers to define integrated fa{\c c}ade solutions and draw from a wide variety of innovative technologies to achieve ambitious energy efficiency goals.

This research is directed toward providing such information and is the result of an on-going collaborative research and development (R\&D) program, supported by the U.S. Department of Energy and the California Energy Commission Public Interest Energy Research (PIER) program.

}, author = {Eleanor S. Lee and Stephen E. Selkowitz and Dennis L. DiBartolomeo and Joseph H. Klems and Robert D. Clear and Kyle S. Konis and Maria Konstantoglou and Mark Perepelitza} } @techreport {1631, title = {Modeling Windows in Energy Plus with Simple Performance Indices}, year = {2009}, month = {10/2009}, abstract = {

The paper describes the development of a model specification for performance monitoring systems for commercial buildings. The specification focuses on four key aspects of performance monitoring:

The aim is to assist building owners in specifying the extensions to their control systems that are required to provide building operators with the information needed to operate their buildings more efficiently and to provide automated diagnostic tools with the information required to detect and diagnose faults and problems that degrade energy performance.

The paper reviews the potential benefits of performance monitoring, describes the specification guide and discusses briefly the ways in which it could be implemented. A prototype advanced visualization tool is also described, along with its application to performance monitoring. The paper concludes with a description of the ways in which the specification and the visualization tool are being disseminated and deployed.

}, author = {Dariush K. Arasteh and Christian Kohler and Brent T. Griffith} } @article {58221, title = {Optical characterization of fritted glass for architectural applications}, journal = {Optical Materials}, volume = {31}, year = {2009}, month = {4/2009}, pages = {949 - 958}, abstract = {

Fritted glass is commonly used as a light diffusing element in modern buildings. Traditionally it has been used for aesthetic purposes but it can also be used for energy savings by incorporating it in novel daylighting systems? To answer such questions the light scattering properties must be properly characterized.

This paper contains measurements of different varieties of fritted glass, ranging from the simplest direct-hemispherical measurements to angle-resolved goniometer measurements. Modeling the light scattering to obtain the full bidirectional scattering distribution function (BSDF) extends the measured data, making it useful in simulation programs such as Window 6 and Radiance. Surface profilometry results and SEM micrographs are included to demonstrate the surface properties of the samples studied.

}, keywords = {BRDF, BTDF, Fritted glass, Integrating sphere, light scattering}, issn = {09253467}, doi = {10.1016/j.optmat.2008.10.050}, author = {Jacob C. Jonsson and Michael D. Rubin and Annica M. Nilsson and Andreas Jonsson and Arne Roos} } @conference {1798, title = {Simulating Complex Window Systems Using BSDF Data}, booktitle = {26th Conference on Passive and Low Energy Architecture (PLEA), June-22-24}, year = {2009}, month = {06/2009}, address = {Quebec City, Canada}, abstract = {

Nowadays, virtual models are commonly used to evaluate the performance of conventional window systems. Complex fenestration systems can be difficult to simulate accurately not only because of their geometry but also because of their optical properties that scatter light in an unpredictable manner. Bi-directional Scattering Distribution Functions (BSDF) have recently been developed based on a mixture of measurements and modelling to characterize the optics of such systems. This paper describes the workflow needed to create then use these BSDF datasets in the Radiance lighting simulation software. Limited comparisons are made between visualizations produced using the standard ray-tracing method, the BSDF method, and that taken in a full-scale outdoor mockup.

}, author = {Maria Konstantoglou and Jacob C. Jonsson and Eleanor S. Lee} } @conference {1252, title = {Deposition Rates of High Power Impulse Magneton Sputtering}, booktitle = {51st Annual Technical Meeting of the Society of Vacuum Coaters}, year = {2008}, month = {04/2008}, abstract = {

High power impulse magnetron sputtering (HIPIMS) is seen by many as the new paradigm in sputtering. It provides significant self-ion assistance to film growth. However, many noticed that deposition rates are reduced, often to less than 50\%, compared to direct current (DC) sputtering rates at the same power input. It is argued here that the reduction is based on the physics of sputtering and self-sputtering, and it should not come as a surprise. Four effects can be distinguished (i) the yield effect caused by the less-than-linear increase of sputtering yield with ion energy, (ii) the impedance effect, influencing what fraction of the target-anode voltage drops in the sheath, (iii) the species effect associated with a change of ions causing sputtering, and (iv) the return effect associated with flux splitting in selfsputtering. The paper is completed by considering some business implications, in particular; it is argued that HIPIMS is a different technology and that its value should be judged comprehensively, not just by rates. Finally, the special case of temperature dependent sputtering is considered, which in some cases may lead to rates exceeding the DC rates.

}, author = {Andr{\'e} Anders} } @article {11733, title = {Developing Low-Conductance Window Frames: Capabilities and Limitations of Current Window Heat Transfer Design Tools}, journal = {Journal of Building Physics}, volume = {32}, number = {2}, year = {2008}, pages = {131-153}, abstract = {

While window frames typically represent 20-30\% of the overall window area, their impact on the total window heat transfer rates may be much larger. This effect is even greater in low-conductance (highly insulating) windows which incorporate very low conductance glazings. Developing low-conductance window frames requires accurate simulation tools for product research and development. Based on a literature review and an evaluation of current methods of modeling heat transfer through window frames, we conclude that current procedures specified in ISO standards are not sufficiently adequate for accurately evaluating heat transfer through the low-conductance frames.

We conclude that the near-term priorities for improving the modeling of heat transfer through low-conductance frames are:

  1. Add 2-D view-factor radiation to standard modeling and examine the current practice of averaging surface emissivity based on area weighting and the process of making an equivalent rectangular frame cavity.
  2. Assess 3-D radiation effects in frame cavities and develop recommendation for inclusion into the design fenestration tools.
  3. Assess existing correlations for convection in vertical cavities using CFD.
  4. Study 2-D and 3-D natural convection heat transfer in frame cavities for cavities that are proven to be deficient from item 3 above. Recommend improved correlations or full CFD modeling into ISO standards and design fenestration tools, if appropriate.
  5. Study 3 D hardware short-circuits and propose methods to ensure that these effects are incorporated into ratings.
  6. Study the heat transfer effects of ventilated frame cavities and propose updated correlations.
}, author = {Arlid Gustavsen and Dariush K. Arasteh and Bj{\o}rn Petter Jelle and Dragan C. Curcija and Christian Kohler} } @article {11798, title = {Electrochromically switched, gas-reservoir metal hydride devices with application to energy-efficient windows}, journal = {Thin Solid Films}, volume = {1}, year = {2008}, month = {08/2003}, address = {Eindhoven, Netherlands}, abstract = {

Proof-of-principle gas-reservoir MnNiMg electrochromic mirror devices have been investigated. In contrast to conventional electrochromic approaches, hydrogen is stored (at low concentration) in the gas volume between glass panes of the insulated glass units (IGUs). The elimination of a solid state ion storage layer simplifies the layer stack, enhances overall transmission, and reduces cost. The cyclic switching properties were demonstrated and system durability improved with the incorporation a thin Zr barrier layer between the MnNiMg layer and the Pd catalyst. Addition of 9\% silver to the palladium catalyst further improved system durability. About 100 full cycles have been demonstrated before devices slow considerably. Degradation of device performance appears to be related to Pd catalyst mobility, rather than delamination or metal layer oxidation issues originally presumed likely to present significant challenges.

}, author = {Andr{\'e} Anders and Jonathan L. Slack and Thomas J. Richardson} } @article {11889, title = {Functionalization of Hydrogen-free Diamond-like Carbon Films using Open-air Dielectric Barrier Discharge Atmospheric Plasma Treatments}, journal = {Applied Surface Science}, volume = {254}, year = {2008}, month = {08/2008}, chapter = {5323}, address = {Boulder, CO}, abstract = {

A dielectric barrier discharge (DBD) technique has been employed to produce uniform atmospheric plasmas of He and N2 gas mixtures in open air in order to functionalize the surface of filtered-arc deposited hydrogen-free diamond-like carbon (DLC) films. XPS measurements were carried out on both untreated and He/N2 DBD plasma-treated DLC surfaces. Chemical states of the C 1s and N 1s peaks were collected and used to characterize the surface bonds. Contact angle measurements were also used to record the short- and long-term variations in wettability of treated and untreated DLC. In addition, cell viability tests were performed to determine the influence of various He/N2 atmospheric plasma treatments on the attachment of osteoblast MC3T3 cells. Current evidence shows the feasibility of atmospheric plasmas in producing long-lasting variations in the surface bonding and surface energy of hydrogen-free DLC and consequently the potential for this technique in the functionalization of DLC-coated devices.

}, keywords = {Cell viability, DLC, Ion implantation and deposition, wettability, XPS}, doi = {10.1016/j.apsusc.2008.02.065}, author = {Jose L. Endrino and Jose F. Marco and Phitsanu Poolcharuansin and Ayalasomayajula R. Phani and Matthew Allen and Jos{\'e} M. Albella and Andr{\'e} Anders} } @article {11897, title = {Gasless sputtering: Opportunities for ultraclean metallization, coatings in space, and propulsion}, journal = {Applied Physics Letters}, volume = {92}, year = {2008}, pages = {221503}, abstract = {

Pulsed magnetron sputtering was demonstrated in high vacuum: no sputter gas was used at any time. Sustained selfsputtering was initiated by multiply charged ions from a short vacuum arc. Copper ion currents to an ion collector in excess of 30 A were measured, implying a plasma density of about 6 x1018 m-3. This technology may prove useful for metal coatings free of noble gas inclusions and suggests that magnetrons could operate in the vacuum of space. In addition to coating objects in space, the momentum of the sputtered atoms and ions may be utilized in space thrusters.

}, author = {Joakim Andersson and Andr{\'e} Anders} } @conference {11927, title = {Highly Insulating Glazing Systems using Non-Structural Center Glazing Layers}, booktitle = {2008 Annual ASHRAE Meeting}, year = {2008}, month = {06/2008}, address = {Salt Lake City, UT}, abstract = {

Three layer insulating glass units with two low-e coatings and an effective gas fill are known to be highly insulating, with center-of-glass U-factors as low as 0.57 W/m2-K (0.10 Btu/h-ft2-{\textdegree}F). Such units have historically been built with center layers of glass or plastic which extend all the way through the spacer system.

This paper shows that triple glazing systems with non-structural center layers which do not create a hermetic seal at the edge have the potential to be as thermally efficient as standard designs, while potentially removing some of the production and product integration issues that have discouraged the use of triples.

}, author = {Dariush K. Arasteh and Howdy Goudey and Christian Kohler} } @conference {12020, title = {Light-scattering properties of a woven shade-screen material used for daylighting and solar heat-gain control}, booktitle = {SPIE Optics+Photonics}, year = {2008}, month = {08/2008}, address = {San Diego, CA}, abstract = {

Shade-screens are widely used in commercial buildings as a way to limit the amount of direct sunlight that can disturb people in the building. The shade screens also reduce the solar heat-gain through glazing the system. Modern energy and daylighting analysis software such as EnergyPlus and Radiance require complete scattering properties of the scattering materials in the system.

In this paper a shade screen used in the LBNL daylighting testbed is characterized using a photogoniometer and a normal angle of incidence integrating sphere. The data is used to create a complete bi-directional scattering distribution function (BDSF) that used in simulation programs.

The resulting BDSF is compared to a model{\textquoteright}s BDSF, both directly and by calculating the solar heat-gain coefficient for a dual-pane system using Window 6.

}, author = {Jacob C. Jonsson and Eleanor S. Lee and Michael D. Rubin} } @conference {61, title = {A Modular Building Controls Virtual Test Bed for the Integration of Heterogeneous Systems}, booktitle = {SimBuild 2008, July 30-August 1}, year = {2008}, month = {08/2008}, address = {Berkeley, CA}, abstract = {

This paper describes the Building Controls Virtual Test Bed (BCVTB) that is currently under development at Lawrence Berkeley National Laboratory. An earlier prototype linked EnergyPlus with controls hardware through embedded SPARK models and demonstrated its value in more cost-effective envelope design and improved controls sequences for the San Francisco Federal Building. The BCVTB presented here is a more modular design based on a middleware that we built using Ptolemy II, a modular software environment for design and analysis of heterogeneous systems. Ptolemy II provides a graphical model building environment, synchronizes the exchanged data and visualizes the system evolution during run-time. Our additions to Ptolemy II allow users to couple to Ptolemy II a prototype version of EnergyPlus, MATLAB/Simulink or other simulation programs for data exchange during run-time. In future work we will also implement a BACnet interface that allows coupling BACnet compliant building automation systems to Ptolemy II. We will present the architecture of the BCVTB and explain how users can add their own simulation programs to the BCVTB. We will then present an example application in which the building envelope and the HVAC system was simulated in EnergyPlus, the supervisory control logic was simulated in MATLAB/Simulink and Ptolemy II was used to exchange data during run-time and to provide real-time visualization as the simulation progresses.

}, author = {Michael Wetter and Philip Haves} } @article {12123, title = {Observation of Ti4+ ions in a high power impulse magnetron sputtering plasma}, journal = {Applied Physics Letters}, volume = {93}, year = {2008}, month = {08/2008}, pages = {71504}, abstract = {

Multiply charged titanium ions including Ti4+ were observed in high power impulse magnetron sputtering discharges. Mass/charge spectrometry was used to identify metal ion species. Quadruply charged titanium ions were identified by isotope-induced broadening at mass/charge 12. Due to their high potential energy, Ti4+ ions give a high yield of secondary electrons, which in turn are likely to be responsible for the generation of multiply charged states.

}, doi = {10.1063/1.2973179}, author = {Joakim Andersson and Arutiun P. Ehiasarian and Andr{\'e} Anders} } @article {58226, title = {Phase transitions in non-hydride switchable mirror thin films}, journal = {Phase Transitions}, volume = {81}, year = {2008}, month = {07/2008}, pages = {807 - 813}, abstract = {

Switchable mirrors modulate incident light by changes in the reflectivity of thin films that are converted by chemical reactions from a metallic reflective state to a semiconducting transparent state. The reactions may be effected by exposure to a gas, by treatment with a liquid reagent, or by electrochemical means. The changes in optical properties coincide with phase transformations. In the examples reviewed here, the reactions are accompanied by substantial volume changes and atomic rearrangement. Bismuth, antimony, and antimony alloy films are switched by electrochemical lithiation. Copper films are electrochemically oxidized to Cu(I) and Cu(II) oxides, which are transparent and opaque, respectively. Morphological changes in all films during cycling lead to degradation in performance without loss of active material. Strategies to improve the cycling stability of these systems are discussed.

}, keywords = {electrochromism, optoelectronics, Switchable mirrors, thin films}, issn = {0141-1594}, doi = {10.1080/01411590801911406}, author = {Thomas J. Richardson} } @article {12244, title = {Self-sputtering far above the runaway threshold: an extraordinary metal ion generator}, journal = {Physical Review Letters}, year = {2008}, abstract = {

When self-sputtering is driven far above the runaway threshold voltage, energetic electrons are made available to produce excess plasma far from the magnetron target. Ionization balance considerations show that the secondary electrons deliver the necessary energy to the remote zone. Thereby, such a system can be an extraordinarily prolific generator of useable metal ions. Contrary to other known sources, the ion current to a substrate can exceed the discharge current. For gasless self-sputtering of copper, the useable ion current scales exponentially with the discharge voltage.

}, author = {Joakim Andersson and Andr{\'e} Anders} } @article {1791, title = {Self-sputtering runaway in high power impulse magnetron sputtering: The role of secondary electrons and multiply charged metal ions}, journal = {Applied Physics Letters}, volume = {92}, year = {2008}, month = {08/2004}, chapter = {201501}, address = {Boulder, CO}, abstract = {

Self-sputtering runaway in high power impulse magnetron sputtering is closely related to the appearance of multiply charged ions. This conclusion is based on the properties of potential emission of secondary electrons and energy balance considerations. The effect is especially strong for materials whose sputtering yield is marginally greater than unity. The absolute deposition rate increases ~ Q1/2, whereas the rate normalized to the average power decreases ~ Q-1/2, with Q being the mean ion charge state number.

}, doi = {10.1063/1.2936307}, author = {Andr{\'e} Anders} } @article {1834, title = {Spatial distribution of average charge state and deposition rate in high power impulse magnetron sputtering of copper}, journal = {Journal of Physics D}, volume = {41}, year = {2008}, pages = {135210-1-6}, abstract = {

The spatial distribution of copper ions and atoms in high power impulse magnetron sputtering (HIPIMS) discharges was determined by (i) measuring the ion current to electrostatic probes and (ii) measuring the film thickness by profilometry. A set of electrostatic and collection probes were placed at different angular positions and distances from the target surface. The angular distribution of the deposition rate and the average charge state of the copper species (including ions and neutrals) were deduced. The discharge showed a distinct transition to a high current mode dominated by copper self-sputtering when the applied voltage exceeded the threshold of 535 V. For a lower voltage, the deposition rate was very low and the average charge state was found to be less than 0.4. For higher voltage (and average power), the absolute deposition rates were much higher, but they were smaller than the corresponding direct current (DC) rates if normalized to the same average power. At the high voltage level, the spatial distribution of the average charge state showed some similarities with the distribution of the magnetic field, suggesting that the generation and motion of copper ions is affected by magnetized electrons. At higher voltage, the average charge state increases with the distance from the target and locally may exceed unity, indicating the presence of significant amounts of doubly charged copper ions.

}, author = {David Horwat and Andr{\'e} Anders} } @article {1859, title = {The structure and electron energy loss near edge structure of tungsten oxide thin films prepared by pulsed cathodic arc deposition and plasma-assisted pulsed magnetron sputtering}, journal = {Journal of Physics: Condensed Matter}, volume = {20}, year = {2008}, month = {04/2008}, pages = {175216}, abstract = {

The microstructure and energy-loss near-edge structure (ELNES) of pulsed cathodic arc and pulsed magnetron sputtered WO3 thin films were investigated. It was found that the cathodic arc deposited material consisted of the α-WO3 phase with a high degree of crystallinity. In contrast, the magnetron sputtered material was highly disordered making it difficult to determine its phase. A self-consistent real space multiple scattering approach was used to calculate the NES of the various phases of WO3. Each phase was found to exhibit a unique NES allowing different phases of WO3 to be identified. The real space approach also allowed the origin of the main features in the NES to be investigated as the cluster size increased. The calculated NES for the room temperature γ-WO3 was found to compare well to previous X-ray absorption spectra and to NES obtained by full-potential band structure calculation.

}, doi = {10.1088/0953-8984/20/17/175216}, author = {Matthew R. Field and Dougal G. McCulloch and Sunnie H.N. Lim and Andr{\'e} Anders and Vicki J. Keast and R.W. Burgess} } @techreport {1972, title = {WINDOW 6.2/THERM 6.2 Research Version User Manual}, year = {2008}, month = {01/2008}, pages = {1-126}, institution = {Lawrence Berkeley National Laboratory}, address = {Berkeley}, abstract = {

WINDOW 6 and THERM 6 Research Versions are software programs developed at Lawrence Berkeley National Laboratory (LBNL) for use by manufacturers, engineers, educators, students, architects, and others to determine the thermal and solar optical properties of glazing and window systems.

WINDOW 6 and THERM 6 are significant updates to LBNL{\textquoteright}s WINDOW 5 and THERM 5 computer program because of the added capability to model complex glazing systems, such as windows with shading systems, in particular venetian blinds. Besides a specific model for venetian blinds and diffusing layers, WINDOW 6 also includes the generic ability to model any complex layer if the Transmittance and Reflectance are known as a function of incoming and outgoing angles.

The algorithms used in these versions of the programs to determine the properties of windows with shading layers are relatively new and should be considered as informative but not definitive.

As such, for windows with shading layers, the results are intended for research purposes only. Pending further validation efforts, results for windows with sh ading layers should not be used for NFRC certified calculations of design decisions in real buildings.

All calculations for products without shading layers are identical to those from WINDOW 5.2.

WINDOW 6 Research Version includes all of the WINDOW 5 capabilities with the addition of shading algorithms from ISO15099 which are incorporated into the program, as well as an extension of those algorithms with the matrix calculation method.

THERM 6 Research Version includes all of the THERM 5 capabilities with the addition of being able to import and model WINDOW 6 glazing systems with shading devices. Those THERM 6 files with shading devices can them be imported into the WINDOW 6 Frame Library and whole windows with shading devices can then be modeled in WINDOW 6.

}, author = {Robin Mitchell and Christian Kohler and Joseph H. Klems and Michael D. Rubin and Dariush K. Arasteh and Charlie Huizenga and Tiefeng Yu and Dragan C. Curcija} } @techreport {58305, title = {Commissioning and verification procedures for the automated roller shade system at The New York Times Headquarters}, year = {2007}, month = {05/2007}, address = {Berkeley}, abstract = {

This document describes the procedures for verification testing of a newly installed automated roller shade system. The automated roller shade system has been designed to control direct sun and window glare while admitting daylight and permitting view out. Procedures in this document focus on verifying that the glare control aspect of this commercially-available system works prior to building occupancy. A high dynamic range luminance measurement tool, developed for this project, is used to verify that the average window luminance is within acceptable limits. Additional spreadsheet and visualization tools are described. The commissioning agent (CxA) and The New York Times will use these procedures during the commissioning phase of the building to verify that the automated control system is operating as intended.

}, author = {Eleanor S. Lee and Robert D. Clear and Gregory J. Ward and Luis L. Fernandes} } @techreport {58303, title = {Daylighting the New York Times Headquarters Building: Final Report: Commissioning Daylighting Systems and Estimation of Demand Response}, year = {2007}, month = {08/2007}, address = {Berkeley}, abstract = {

The technical energy-savings potential for smart integrated window-daylighting systems is excellent and can yield significant reductions in US commercial building energy use if adopted by a significant percentage of the market. However, conventional automated shades and daylighting controls have been commercially available for over two decades with less than 1-2\% market penetration in the US. As with many innovations, the problem with accelerating market adoption is one of demonstrating real performance and decreasing risk and cost. The New York Times considered use of such daylighting systems for their new 139,426 m2 (1.5 Mft2) headquarters building in downtown Manhattan.

In the initial phase of work, The New York Times employed a unique approach to create a competitive marketplace for daylighting systems and to address their concerns about risk by building a full-scale daylighting mockup and evaluating commercially-available products. This field test formed the strategic cornerstone for accelerating an industry response to the building owners{\textquoteright} challenge to a sleepy market. A procurement specification was produced and bids were received that met The Times cost-effective criteria. The Times decided to proceed with using these innovative systems in their new building.

This next phase of work consisted of two distinct tasks: 1) to develop and use commissioning tools and procedures to insure that the automated shade and daylighting control systems operate as intended prior to occupancy; and 2) to estimate the peak demand savings resulting from different levels of demand response (DR) control strategies (from moderate to severe load curtailment) and then determine the financial implications given various DR programs offered by the local utility and New York Independent System Operator in the area.

Commissioning daylighting control systems is mandatory to insure that design intent is met, that the systems are tuned to optimal performance, and to eliminate problems and errors before occupants move in. Commissioning tools were developed and procedures were defined and then used to verify that the daylighting systems operated according to the technical specifications. For both lighting control and shading systems, the Times and the manufacturers were able to resolve most of the bugs and fine-tune the systems prior to occupancy.

The demand response (DR) strategies at the New York Times building involve unique state-of-the-art systems with dimmable ballasts, movable shades on the glass facade, and underfloor air HVAC. The process to develop the demand response strategies, the results of the EnergyPlus model, the activities to implement the DR strategies in the controls design at the New York Times Headquarters building and the evaluation of economics of participating in DR programs are presented and discussed. The DR simulation iv efforts for this building design are novel, with an innovative building owner evaluating DR and future DR program participation strategies during the design and construction phase using advanced simulation tools.

}, keywords = {automated daylighting controls, automated window shades, daylighting, demand response, energy-efficiency, visual comfort}, author = {Eleanor S. Lee and Glenn D. Hughes and Robert D. Clear and Luis L. Fernandes and Sila Kiliccote and Mary Ann Piette and Francis M. Rubinstein and Stephen E. Selkowitz} } @article {11811, title = {Energy and visual comfort performance of electrochromic windows with overhangs}, journal = {Building and Environment}, volume = {42}, year = {2007}, month = {06/2007}, pages = {2439-2449}, chapter = {2439}, abstract = {

DOE-2 building energy simulations were conducted to determine if there were practical architectural and control strategy solutions that would enable electrochromic (EC) windows to significantly improve visual comfort without eroding energy-efficiency benefits. EC windows were combined with overhangs since opaque overhangs provide protection from direct sun which EC windows are unable to do alone. The window wall was divided into an upper and lower aperture so that various combinations of overhang position and control strategies could be considered. The overhang was positioned either at the top of the upper window aperture or between the upper and lower apertures. Overhang depth was varied. EC control strategies were fully bleached at all times, modulated based on incident vertical solar radiation limits, or modulated to meet the design work plane illuminance with daylight. The EC performance was compared to a state-of-the-art spectrally selective low-e window with the same divided window wall, window size, and overhang as the EC configuration. The reference window was also combined with an interior shade which was manually deployed to control glare and direct sun. Both systems had the same daylighting control system to dim the electric lighting. Results were given for south-facing private offices in a typical commercial building.

In hot and cold climates such as Houston and Chicago, EC windows with overhangs can significantly reduce the average annual daylight glare index (DGI) and deliver significant annual energy use savings if the window area is large. Total primary annual energy use was increased by 2-5\% for moderate-area windows in either climate but decreased by 10\% in Chicago and 5\% in Houston for large-area windows. Peak electric demand can be reduced by 7-8\% for moderate-area windows and by 14-16\% for large-area windows in either climate. Energy and peak demand reductions can be significantly greater if the reference case does not have exterior shading or state-of-the-art glass.

}, keywords = {building simulation, Control algorithms, daylighting, Electrochromic windows, energy efficiency}, doi = {10.1016/j.buildenv.2006.04.016}, author = {Eleanor S. Lee and Aslihan Tavil} } @conference {1420, title = {Field Evaluation of Low-E Storm Windows}, booktitle = {Thermal Performance of the Exterior Envelopes of Whole Buildings X International Conference}, volume = {277}, year = {2007}, month = {12/2007}, pages = {228-236}, address = {Clearwater Beach, FL}, abstract = {

A field evaluation comparing the performance of low emittance (low-e) storm windows with both standard clear storm windows and no storm windows was performed in a cold climate. Six homes with single pane windows were monitored over the period of one heating season. The homes were monitored with no storm windows and with new storm windows. The storm windows installed on four of the six homes included a hard coat, pyrolitic, low-e coating while the storm windows for the other two homes had traditional clear glass. Overall heating load reduction due to the storm windows was 13\% with the clear glass and 21\% with the low-e windows. Simple paybacks for the addition of the storm windows were 10 years for the clear glass and 4.5 years for the low-e storm windows.

}, author = {S. Craig Drumheller and Christian Kohler and Stefanie Minen} } @article {12037, title = {A low-energy linear oxygen plasma source}, journal = {Review of Scientific Instruments}, volume = {78}, year = {2007}, month = {04/2007}, chapter = {043104}, abstract = {

A new version of a constricted plasma source is described, characterized by all metal-ceramic construction, a linear slit exit of 180 mm length, and cw operation typically 50 kHz at an average power of 1.5 kW. The plasma source is here operated with oxygen gas, producing streaming plasma that contains mainly positive molecular and atomic ions, and to a much lesser degree, negative ions. The maximum total ion current obtained was about 0.5 A. The fraction of atomic ions reached more than 10\% of all ions when the flow rate was less then 10 SCCM O2, corresponding to a chamber pressure of about 0.5 Pa for the selected pumping speed. The energy distribution functions of the different ion species were measured with a combined mass spectrometer and energy analyzer. The time-averaged distribution functions were broad and ranged from about 30 to 90 eV at 200 kHz and higher frequencies, while they were only several eV broad at 50 kHz and lower frequencies, with the maximum located at about 40 eV for the grounded anode case. This maximum was shifted down to about 7 eV when the anode was floating, indicating the important role of the plasma potential for the ion energy for a given substrate potential. The source could be scaled to greater length and may be useful for functionalization of surfaces and plasma-assisted deposition of compound films.

}, keywords = {atomic and molecular ions, Constricted plasma source, ion energy distribution functions, oxygen plasma}, author = {Andr{\'e} Anders and Georgy Yu Yushkov} } @techreport {58255, title = {Moving from Niche to Mainstream Markets: Addressing the High Cost of Daylighting Systems}, year = {2007}, month = {05/2007}, address = {New York, New York}, abstract = {

Transcript of a lecture given by Glenn Hughes, Managing Director of Construction, The New York Times at LightFair International: Daylighting Institute, New York, New York, May 6, 2007.

}, author = {Glenn D. Hughes} } @conference {12116, title = {NFRC Interlaboratory Comparison on Optical Properties}, booktitle = {NFRC Conference}, year = {2007}, month = {03/2006}, address = {San Diego, CA}, abstract = {

As part of the NFRC rating process, optical data on glazing materials is combined with other information to calculate various properties of a window product. The administrative procedure for gathering such optical data is governed by NFRC 3021, which in turn refers to NFRC 3002 and NFRC 3013 for the technical procedures by which the optical properties are determined in the solar and infrared ranges, respectively. In practice, the data is compiled by the Lawrence Berkeley National Laboratory (LBNL) and becomes part of the International Glazing Database (IGDB).

NFRC 302 specifies that submitters of optical data or their representatives must participate in a {\textquoteright}round robin{\textquoteright} or ILC. Often, manufacturers of glazing materials have the optical equipment necessary to perform their own measurements. NFRC 302 allows manufacturers to submit their own measured data subject to a set of checks including peer review to ensure the accuracy of such data. In some cases the glazing manufacturer does not have the required equipment and so may choose to send the samples to a test laboratory. In other cases the manufacturer of the final product such as a laminate may ask a component supplier, often a glass manufacturer, to perform the measurements for them. In such cases the "representative" must have qualified by participating in the ILC. An ILC is only required every four years and it would be unfair to expect new product submitters to wait so long. Therefore, two interpretations are made on occasion: (1) a new data submitter does not have to wait for the next ILC if they submit a set of samples with their first dataset for comparison at LBNL (a mini ILC), or (2) if they have participated in an ILC conducted by some other reputable independent organization.

}, author = {Jacob C. Jonsson and Michael D. Rubin} } @article {12126, title = {Obtaining the Bidirectional Transfer Distribution Function of Isotropically Scattering Materials Using an Integrating Sphere}, journal = {Optics Communications}, volume = {277}, year = {2007}, pages = {228-236}, abstract = {

This paper demonstrates a method to determine the bidirectional transfer distribution function (BTDF) using an integrating sphere. Information about the sample{\textquoteright}s angle dependent scattering is obtained by making transmittance measurements with the sample at different distances from the integrating sphere. Knowledge about the illuminated area of the sample and the geometry of the sphere port in combination with the measured data combines to an system of equations that includes the angle dependent transmittance. The resulting system of equations is an ill-posed problem which rarely gives a physical solution. A solvable system is obtained by using Tikhonov regularization on the ill-posed problem. The solution to this system can then be used to obtain the BTDF. Four bulk-scattering samples were characterised using both two goniophotometers and the described method to verify the validity of the new method. The agreement shown is great for the more diffuse samples. The solution to the low-scattering samples contains unphysical oscillations, but still gives the correct shape of the solution. The origin of the oscillations and why they are more prominent in low-scattering samples are discussed.

}, author = {Jacob C. Jonsson and Henrik Branden} } @article {12182, title = {Physical properties of erbium implanted tungsten oxide films deposited by reactive dual magnetron sputtering}, journal = {Thin Solid Films}, volume = {515}, number = {8}, year = {2007}, month = {05/2007}, pages = {5264-5269}, chapter = {5264}, abstract = {

Amorphous and partially crystalline WO3 thin films were prepared by reactive dual magnetron sputtering and successively implanted by erbium ions with a fluence in the range from 7.7 x 1014 to 5 x 1015 ions/cm2. The electrical and optical properties were studied as a function of the film deposition parameters and the ion fluence. Ion implantation caused a strong decrease of the resistivity, a moderate decrease of the index of refraction and a moderate increase of the extinction coefficient in the visible and near infrared, while the optical band gap remained almost unchanged. These effects could be largely ascribed to ion-induced oxygen deficiency. When annealed in air, the already low resistivities of the implanted samples decreased further up to 70{\textdegree}C, whereas oxidation, and hence a strong increase of the resistivity, was observed at higher annealing temperatures

}, keywords = {Dual magnetron sputtering, electrical resistivity, Er ion implantation, optical properties, tungsten oxide films}, doi = {10.1016/j.tsf.2006.12.179}, author = {Sodky H. Mohamed and Andr{\'e} Anders} } @conference {1731, title = {Physics of High Power Impulse Magnetron Sputtering}, booktitle = {ISSP2007: The 9th International Symposium on Sputtering \& Plasma Processes}, year = {2007}, abstract = {

High power impulse magnetron sputtering is characterized by discharge pulses whose target power density exceeds conventional sputtering power densities by two orders of magnitude or more; the goal is to provide a large flux of ionized sputtered material. The processes of pulse evolution are briefly reviewed, including secondary electron emission, self-sputtering, and rarefaction. Using a pulse power supply capable of providing constant voltage for target peak power densities up to 5 kW/cm2, the evolution of the current-voltage characteristics was investigated for copper and titanium. It is shown that the characteristic cannot be reduced to value pairs. Rather, a strong but reproducible development exists. The details depend on the argon pressure and applied voltage. Each target material exhibits a distinct and sharp transition to a high current regime that appears to be dominated by metal plasma. Despite the higher sputter yields for copper, the transition to the high current regime occurs much earlier and stronger for titanium, which may be attributed to a higher secondary electron yield and hence a higher density of electrons confined in the magnetron structure. At high currents, the closed-drift Hall current generates a magnetic field that weakens plasma confinement, thereby enabling large ion currents to reach a biased substrate.

}, author = {Andr{\'e} Anders and Joakim Andersson and David Horwat and Arutiun P. Ehiasarian} } @conference {1732, title = {Plasma and Ion Assistance in Physical Vapor Deposition: A Historical Perspective}, booktitle = {50th Technical Annual Meeting of the Society of Vacuum Coaters}, year = {2007}, abstract = {

Deposition of films using plasma or plasma-assist can be traced back surprisingly far, namely to the 18th century for arcs and to the 19th century for sputtering. However, only since the 1960s the coatings community considered other processes than evaporation for large scale commercial use. Ion Plating was perhaps the first important process, introducing vapor ionization and substrate bias to generate a beam of ions arriving on the surface of the growing film. Rather independently, cathodic arc deposition was established as an energetic condensation process, first in the former Soviet Union in the 1970s, and in the 1980s in the Western Hemisphere.

About a dozen various ion-based coating technologies evolved in the last decades, all characterized by specific plasma or ion generation processes. Gridded and gridless ion sources were taken from space propulsion and applied to thin film deposition. Modeling and simulation have helped to make plasma and ions effects to be reasonably well understood. Yet{\textemdash}due to the complex, often non-linear and non-equilibrium nature of plasma and surface interactions{\textemdash}there is still a place for the experienced ion and plasma "sourcerer."

}, author = {Andr{\'e} Anders} } @techreport {58306, title = {Quick Start Guide: Commissioning and verification procedures for the automated roller shade system at The New York Times Headquarters}, year = {2007}, month = {05/2007}, address = {Berkeley}, abstract = {

This quick start guide summarizes the steps required to verify the performance of a newly installed automated roller shade system. The automated roller shade system at The New York Times Headquarters has been designed to control direct sun and window glare while admitting daylight and permitting view out. Procedures in this guide focus on verifying that the glare control aspect of this commerciallyavailable system works prior to building occupancy. A high dynamic range luminance measurement tool, developed for this project, is used to verify that the average window luminance is within acceptable limits. The commissioning agent (CxA) and The New York Times will use these procedures during the commissioning phase of the building to verify that the automated control system is operating as intended.

}, author = {Eleanor S. Lee and Robert D. Clear and Gregory J. Ward and Luis L. Fernandes} } @techreport {1846, title = {State-of-the-Art Highly Insulating Window Frames - Research and Market Review}, number = {Project report 6}, year = {2007}, institution = {INTEF Building and Infrastructure}, address = {Olso}, abstract = {

This document reports the findings of a market and research review related to state-of-the-art highly insulating window frames. The market review focuses on window frames that satisfy the Passivhaus requirements (window U-value less or equal to 0.8 W/m2K), while other examples are also given in order to show the variety of materials and solutions that may be used for constructing window frames with a low thermal transmittance (U-value). The market search shows that several combinations of materials are used in order to obtain window frames with a low U-value. The most common insulating material seems to be Polyurethane (PUR), which is used together with most of the common structural materials such as wood, aluminum, and PVC.

The frame research review also shows examples of window frames developed in order to increase the energy efficiency of the frames and the glazings which the frames are to be used together with. The authors find that two main tracks are used in searching for better solutions. The first one is to minimize the heat losses through the frame itself. The result is that conductive materials are replaced by highly thermal insulating materials and air cavities. The other option is to reduce the window frame area to a minimum, which is done by focusing on the net energy gain by the entire window (frame, spacer and glazing). Literature shows that a window with a higher U-value may give a net energy gain to a building that is higher than a window with a smaller U-value. The net energy gain is calculated by subtracting the transmission losses through the window from the solar energy passing through the windows. The net energy gain depends on frame versus glazing area, solar factor, solar irradiance, calculation period and U-value.

The frame research review also discusses heat transfer modeling issues related to window frames. Thermal performance increasing measures, surface modeling, and frame cavity modeling are among the topics discussed. The review shows that the current knowledge gives the basis for improving the calculation procedures in the calculation standards. At the same time it is room for improvement within some areas, e.g. to fully understand the natural convection effects inside irregular vertical frame cavities (jambs) and ventilated frame cavities.

}, keywords = {energy use, Passivhaus, thermal transmittance, U-value, window frame, windows}, isbn = {978-82-536-0970-6}, author = {Arlid Gustavsen and Bj{\o}rn Petter Jelle and Dariush K. Arasteh and Christian Kohler} } @techreport {1220, title = {Technical Note: Commissioning procedures for the dimmable daylighting control systems}, year = {2007}, month = {03/2007}, address = {Berkeley, California}, abstract = {

This memorandum presents a procedure for verifying that the lighting controls manufacturer has properly calibrated the response of control system for the overhead lighting at the NY Times building. Proper calibration of the lighting control system in this building means adjusting the output of the overhead lighting system so that the following criteria are satisfied:

  1. The average illuminance over a representative portion of the workstation task surface is at least 90\% of the target design level (450 lux is 90\% of the target 500 lux level1) and
  2. The overhead lights in the vicinity of the workstation are significantly dimmed (or OFF) if the average illuminance is \> 125\% (650 lux) of the target level.
}, author = {Francis M. Rubinstein} } @conference {1935, title = {Two-Dimensional Computational Fluid Dynamics and Conduction Simulations of Heat Transfer in Horizontal Window Frames with Internal Cavities}, booktitle = {2007 ASHRAE Winter Meeting}, year = {2007}, month = {01/2007}, address = {Dallas, TX}, abstract = {

This paper assesses the accuracy of the simplified frame cavity conduction/convection and radiation models presented in ISO 15099 and used in software for rating and labeling window products. Temperatures and U-factors for typical horizontal window frames with internal cavities are compared; results from Computational Fluid Dynamics (CFD) simulations with detailed radiation modeling are used as a reference.

Four different frames were studied. Two were made of polyvinyl chloride (PVC) and two of aluminum. For each frame, six different simulations were performed, two with a CFD code and four with a building-component thermal-simulation tool using the Finite Element Method (FEM). This FEM tool addresses convection using correlations from ISO 15099; it addressed radiation with either correlations from ISO 15099 or with a detailed, view-factor-based radiation model. Calculations were performed using the CFD code with and without fluid flow in the window frame cavities; the calculations without fluid flow were performed to verify that the CFD code and the building-component thermal-simulation tool produced consistent results. With the FEM-code, the practice of subdividing small frame cavities was examined, in some cases not subdividing, in some cases subdividing cavities with interconnections smaller than five millimeters (mm) (ISO 15099) and in some cases subdividing cavities with interconnections smaller than seven mm (a breakpoint that has been suggested in other studies). For the various frames, the calculated U-factors were found to be quite comparable (the maximum difference between the reference CFD simulation and the other simulations was found to be 13.2 percent). A maximum difference of 8.5 percent was found between the CFD simulation and the FEM simulation using ISO 15099 procedures. The ISO 15099 correlation works best for frames with high U-factors. For more efficient frames, the relative differences among various simulations are larger.

Temperature was also compared, at selected locations on the frames. Small differences was found in the results from model to model.

Finally, the effectiveness of the ISO cavity radiation algorithms was examined by comparing results from these algorithms to detailed radiation calculations (from both programs). Our results suggest that improvements in cavity heat transfer calculations can be obtained by using detailed radiation modeling (i.e. view-factor or ray-tracing models), and that incorporation of these strategies may be more important for improving the accuracy of results than the use of CFD modeling for horizontal cavities.

}, author = {Arlid Gustavsen and Christian Kohler and Arvid Dalehaug and Dariush K. Arasteh} } @techreport {1077, title = {Advancement of Electrochromic Windows}, year = {2006}, month = {04/2006}, abstract = {

This guide provides consumer-oriented information about switchable electrochromic (EC) windows. Electrochromic windows change tint with a small applied voltage, providing building owners and occupants with the option to have clear or tinted windows at any time, irrespective of whether it{\textquoteright}s sunny or cloudy. EC windows can be manually or automatically controlled based on daylight, solar heat gain, glare, view, energy-efficiency, peak electricity demand response, or other criteria. Window controls can be integrated with other building systems, such as lighting and heating/cooling mechanical systems, to optimize interior environmental conditions, occupant comfort, and energy-efficiency.

}, keywords = {commercial buildings, daylight, daylighting controls, Electrochromic windows, energy efficiency, human factors, peak demand, switchable windows, visual comfort}, author = {Eleanor S. Lee and Stephen E. Selkowitz and Robert D. Clear and Dennis L. DiBartolomeo and Joseph H. Klems and Luis L. Fernandes and Gregory J. Ward and Vorapat Inkarojrit and Mehry Yazdanian} } @techreport {1264, title = {A Design Guide for Early-Market Electrochromic Windows}, year = {2006}, abstract = {

Switchable variable-tint electrochromic windows preserve the view out while modulating transmitted light, glare, and solar heat gains and can reduce energy use and peak demand. To provide designers objective information on the risks and benefits of this technology, this study offers data from simulations, laboratory tests, and a 2.5-year field test of prototype large-area electrochromic windows evaluated under outdoor sun and sky conditions. The study characterized the prototypes in terms of transmittance range, coloring uniformity, switching speed, and control accuracy. It also integrated the windows with a daylighting control system and then used sensors and algorithms to balance energy efficiency and visual comfort, demonstrating the importance of intelligent design and control strategies to provide the best performance. Compared to an efficient low-e window with the same daylighting control system, the electrochromic window showed annual peak cooling load reductions from control of solar heat gains of 19-26\% and lighting energy use savings of 48-67\% when controlled for visual comfort. Subjects strongly preferred the electrochromic window over the reference window, with preferences related to perceived reductions in glare, reflections on the computer monitor, and window luminance. The EC windows provide provided the benefit of greater access to view year-round. Though not definitive, findings can be of great value to building professionals.

}, author = {Eleanor S. Lee and Stephen E. Selkowitz and Robert D. Clear and Dennis L. DiBartolomeo and Joseph H. Klems and Luis L. Fernandes and Gregory J. Ward and Vorapat Inkarojrit and Mehry Yazdanian} } @conference {165, title = {Dynamic Controls for Energy Efficiency and Demand Response: Framework Concepts and a New Construction Case Study in New York}, booktitle = {2006 ACEEE Summer Study on Energy Efficiency in Buildings}, year = {2006}, month = {06/2006}, address = {Pacific Grove, CA}, abstract = {

Many of today{\textquoteright}s advanced building control systems are designed to improve granularity of control for energy efficiency. Examples include direct digital controls for building heating, ventilation, and cooling systems (HVAC), and dimmable ballasts for continuous dimming for daylighting applications. This paper discusses recent research on the use of new and existing controls in commercial buildings for integrated energy efficiency and demand response (DR). The paper discusses the use of DR controls strategies in commercial buildings and provides specific details on DR control strategy design concepts for a new building in New York. We present preliminary results from EnergyPlus simulations of the DR strategies at the New York Times Headquarters building currently under construction. The DR strategies at the Times building involve unique state of the art systems with dimmable ballasts, movable shades on the glass facade, and underfloor air HVAC. The simulation efforts at this building are novel, with an innovative building owner considering DR and future DR program participation strategies during the design phase. This paper also discusses commissioning plans for the DR strategies. The trends in integration of various systems through the EMCS, master versus supervisory controls and dynamic operational modes concepts are presented and future research directions are outlined.

}, author = {Sila Kiliccote and Mary Ann Piette and David S. Watson and Glenn D. Hughes} } @article {11783, title = {Effects of Overhangs on the Performance of Electrochromic Windows}, journal = {Architectural Science Review}, number = {6-Dec}, year = {2006}, abstract = {

In this study, various facade designs with overhangs combined with electrochromic (EC) window control strategies were modeled for a typical commercial office building in a hot and cold climate using the DOE 2.1E building energy simulation program. EC windows were combined with overhangs since opaque overhangs provide protection from direct sun which EC windows are unable to do alone. The window wall was divided into an upper and lower aperture so that various combinations of overhang position and control strategies could be considered. The overhang was positioned either at the top of the upper window aperture or between the upper and lower apertures. Overhang depth was varied. EC control strategies were fully bleached at all times, modulated based on incident vertical solar radiation limits, or modulated to meet the design work plane illuminance with daylight. Annual total energy use (ATE), peak electric demand (PED), average daylight illuminance (DI), and daylight glare index (DGI) for south-facing private offices were computed and compared to determine which combinations of fa{\c c}ade design and control strategies yielded the greatest energy efficiency, daylight amenity, and visual comfort.

}, author = {Aslihan Tavil and Eleanor S. Lee} } @conference {11848, title = {Evaluating Fenestration Products for Zero-Energy Buildings: Issues for Discussion}, booktitle = {SimBuild 2006: Building Sustainability and Performance Through Simulation}, year = {2006}, month = {08/2006}, address = {Cambridge, MA}, abstract = {

Computer modeling to determine fenestration product energy properties (U-factor, SHGC, VT) has emerged as the most cost-effective and accurate means to quantify them. Fenestration product simulation tools have been effective in increasing the use of low-e coatings and gas fills in insulating glass and in the widespread use of insulating frame designs and materials. However, for more efficient fenestration products (low heat loss products, dynamic products, products with non-specular optical characteristics, light redirecting products) to achieve widespread use, fenestration modeling software needs to be improved.

This paper addresses the following questions:

1) Are the current properties (U, SHGC, VT) calculated sufficient to compare and distinguish between windows suitable for Zero Energy Buildings and conventional window products? If not, what data on the thermal and optical performance, on comfort, and on peak demand of windows is needed.

2) Are the algorithms in the tools sufficient to model the thermal and optical processes? Are specific heat transfer and optical effects not accounted for? Is the existing level of accuracy enough to distinguish between products designed for Zero Energy Buildings? Is the current input data adequate?

}, author = {Dariush K. Arasteh and Dragan C. Curcija and Yu Joe Huang and Charlie Huizenga and Christian Kohler} } @techreport {58258, title = {Experimental Validation of Daylighting Simulation Methods for Complex Fenestration Systems}, year = {2006}, month = {05/2006}, abstract = {

The objective of this paper is to assess the capability of existing lighting simulation methods to predict the performance of complex fenestration systems, which are becoming a commonly used component in buildings construction domain. A specific experimental protocol was conducted to collect reliable reference data based on illuminance measurements inside a black box with (and without) one complex glazing sample facing a measured external luminance distribution. Two types of simulation methods were tested and compared: The first is based on modeling the glazing sample in a ray-tracing simulation program and the second is based on use of the samples{\textquoteright} BTDF data. The BTDF data sets were combined with the external luminance distribution to predict the flux distribution inside the room and the resulting illuminance values at the reference points. The comparison between the experimental reference data and the simulation results showed that the influence of the CFS could be predicted with good accuracy.

}, author = {Fawaz Maamari and Marilyn Andersen and Jan de Boer and William L. Carroll and Dominique Dumortier and Phillip Greenup} } @article {11879, title = {Filtered cathodic arc deposition with ion-species-selective bias}, journal = {Review of Scientific Instruments}, year = {2006}, abstract = {

A dual-cathode arc plasma source was combined with a computer-controlled bias amplifier such as to synchronize substrate bias with the pulsed production of plasma. In this way, bias can be applied in a material-selective way. The principle has been applied to the synthesis metal-doped diamond-like carbon films, where the bias was applied and adjusted when the carbon plasma was condensing, and the substrate was at ground when the metal was incorporated. In doing so, excessive sputtering by too-energetic metal ions can be avoided while the sp3/sp2 ratio can be adjusted. It is shown that the resistivity of the film can be tuned by this species-selective bias. The principle can be extended to multiple-material plasma sources and complex materials.

}, author = {Andr{\'e} Anders and Nitisak Pasaja and Sakon Sansongsiri and Sunnie H.N. Lim} } @article {12067, title = {Metal plasmas for the fabrication of nanostructures}, journal = {J. Phys. D: Appl. Phys.}, year = {2006}, abstract = {

A review is provided covering metal plasma production, the energetic condensation of metal plasmas, and the formation of nanostructures using such plasmas. Plasma production techniques include pulsed laser ablation, filtered cathodic arcs, and various forms of ionized physical vapor deposition, namely magnetron sputtering with ionization of sputtered atoms in radio frequency discharges, self-sputtering, and high power impulse magnetron sputtering. The discussion of energetic condensation focuses on the control of kinetic energy by biasing and also includes considerations of the potential energy and the processes occurring at subplantation and implantation. In the final section on nanostructures, two different approaches are discussed. In the top-down approach, the primary nanostructures are lithographically produced and metal plasma is used to coat or fill trenches and vias. Additionally, multilayers with nanosize periods (nanolaminates) can be produced. In the bottom-up approach, thermodynamic forces are used to fabricate nanocomposites and nanoporous materials by decomposition and dealloying.

}, author = {Andr{\'e} Anders} } @conference {12088, title = {Monitored Energy Performance of Electrochromic Windows Controlled for Daylight and Visual Comfort}, booktitle = {2006 ASHRAE Annual Meeting}, volume = {112 Issue 2}, year = {2006}, month = {10/2006}, address = {Quebec City, Canada}, abstract = {

A 20-month field study was conducted to measure the energy performance of south-facing large-area tungsten-oxide absorptive electrochromic (EC) windows with a broad switching range in a private office setting. The EC windows were controlled by a variety of means to bring in daylight while minimizing window glare. For some cases, a Venetian blind was coupled with the EC window to block direct sun. Some tests also involved dividing the EC window wall into zones where the upper EC zone was controlled to admit daylight while the lower zone was controlled to prevent glare yet permit view. If visual comfort requirements are addressed by EC control and Venetian blinds, a 2-zone EC window configuration provided average daily lighting energy savings of 10-15\% compared to the reference case with fully lowered Venetian blinds. Cooling load reductions were 0-3\%. If the reference case assumes no daylighting controls, lighting energy savings would be 44-11\%. Peak demand reductions due to window cooling load, given a critical demand-response mode, were 19-26\% maximum on clear sunny days. Peak demand reductions in lighting energy use were 0\% or 72-100\% compared to a reference case with and without daylighting controls, respectively. Lighting energy use was found to be very sensitive to how glare and sun is controlled. Additional research should be conducted to fine-tune EC control for visual comfort based on solar conditions so as to increase lighting energy savings.

}, keywords = {building automation and controls, Building envelope, commercial buildings}, author = {Eleanor S. Lee and Dennis L. DiBartolomeo and Joseph H. Klems and Mehry Yazdanian and Stephen E. Selkowitz} } @article {12113, title = {The New York Times Headquarters Daylighting Mockup: Monitored Performance of the Daylighting Control System}, journal = {Energy \& Buildings}, volume = {38}, number = {7}, year = {2006}, pages = {914-929}, abstract = {

A nine-month monitored field study of the performance of automated roller shades and daylighting controls was conducted in a 401 m2 unoccupied, furnished daylighting mockup. The mockup mimicked the southwest corner of a new 110 km2 commercial building in New York, New York, where The New York Times will be the major tenant. This paper focuses on evaluating the performance of two daylighting control systems installed in separate areas of an open plan office with 1.2-m high workstation partitions: 1) Area A had 0-10 V dimmable ballasts with an open-loop proportional control system and an automated shade controlled to reduce window glare and increase daylight, and 2) Area B had digital addressable lighting interface (DALI) ballasts with a closed-loop integral reset control system and an automated shade controlled to block direct sun. Daylighting control system performance and lighting energy use were monitored. The daylighting control systems demonstrated very reliable performance after they were commissioned properly. Work plane illuminance levels were maintained above 90\% of the maximum fluorescent illuminance level for 99.9+/-0.5\% and 97.9+/-6.1\% of the day on average over the monitored period, respectively, in Areas A and B. Daily lighting energy use savings were significant in both Areas over the equinox-to-equinox period compared to a non-daylit reference case. At 3.35 m from the window, 30\% average savings were achieved with a sidelit west-facing condition in Area A while 50-60\% were achieved with a bilateral daylit south-facing condition in Area B. At 4.57-9.14 m from the window, 5-10\% and 25-40\% savings were achieved in Areas A and B, respectively. Average savings for the 7-m deep dimming zone were 20-23\% and 52-59\% for Areas A and B, respectively, depending on the lighting schedule. The large savings and good reliability can be attributed to the automatic management of the interior shades. The DALI-based system exhibited faulty behavior that remains unexplained, but operational errors are expected to be resolved as DALI products reach full maturity. The building owner received very competitive bids ($30-75 US/DALI ballast) and was able to justify use of the daylighting control system based on operational cost savings and increased amenity. Additional energy savings due to reduced solar and lighting heat gains were not quantified but will add to the total operational cost savings.

}, author = {Eleanor S. Lee and Stephen E. Selkowitz} } @conference {12166, title = {Performance Criteria for Residential Zero Energy Windows}, booktitle = {2007 ASHRAE Winter Meeting}, year = {2006}, month = {01/2007}, address = {Dallas, TX}, abstract = {

This paper shows that the energy requirements for today{\textquoteright}s typical efficient window products (i.e. ENERGY STAR products) are significant when compared to the needs of Zero Energy Homes (ZEHs). Through the use of whole house energy modeling, typical efficient products are evaluated in five US climates and compared against the requirements for ZEHs. Products which meet these needs are defined as a function of climate. In heating dominated climates, windows with U-factors of 0.10 Btu/hr-ft2-F (0.57 W/m2-K) will become energy neutral. In mixed heating/cooling climates a low U-factor is not as significant as the ability to modulate from high SHGCs (heating season) to low SHGCs (cooling season).

}, author = {Dariush K. Arasteh and Howdy Goudey and Yu Joe Huang and Christian Kohler and Robin Mitchell} } @article {12188, title = {Plasma biasing to control the growth conditions of diamond-like carbon}, journal = {Surface and Coatings Technology}, volume = {201}, year = {2006}, month = {01/2007}, pages = {4628-4632}, chapter = {4628}, abstract = {

It is well known that the structure and properties of diamond-like carbon, and in particular the sp3/sp2 ratio, can be controlled by the energy of the condensing carbon ions or atoms. In many practical cases, the energy of ions arriving at the surface of the growing film is determined by the bias applied to the substrate. The bias causes a sheath to form between substrate and plasma in which the potential difference between plasma potential and surface potential drops. In this contribution, we demonstrate that the same results can be obtained with grounded substrates by shifting the plasma potential. This plasma biasing (as opposed to substrate biasing) is shown to work well with pulsed cathodic carbon arcs, resulting in tetrahedral amorphous carbon (ta-C) films that are comparable to the films obtained with the conventional substrate bias. To verify the plasma bias approach, ta-C films were deposited by both conventional and plasma bias and characterized by transmission electron microscopy (TEM) and electron energy loss spectrometry (EELS). Detailed data for comparison of these films are provided.

}, keywords = {Diamond-like carbon films, Electron energy loss spectroscopy, Plasma bias, Substrate bias, transmission electron microscopy}, doi = {10.1016/j.surfcoat.2006.09.313}, author = {Andr{\'e} Anders and Nitisak Pasaja and Sunnie H.N. Lim and Tim C. Petersen and Vicki J. Keast} } @article {1812, title = {Smoothing of ultrathin silver films by transition metal seeding}, journal = {Applied Physics Letters}, year = {2006}, abstract = {

The nucleation and coalescence of silver islands on coated glass was investigated by in-situ measurements of the sheet resistance. Sub-monolayer amounts of transition metals (Nb, Ti, Ni, Cr, Zr, Ta, and Mo) were deposited prior to the deposition of silver. It was found that some, but not all, of the transition metals lead to coalescence of silver at nominally thinner films with smoother topology. The smoothing effect of the transition metal at sub-monolayer thickness can be explained by a thermodynamic model of surface energies.

}, author = {Andr{\'e} Anders and Eungsun Byon and Dong-Ho Kim and Kentaro Fukuda and Sunnie H.N. Lim} } @article {1857, title = {Structural, optical and electrical properties of WOxNy films deposited by reactive dual magnetron sputtering}, journal = {Surface and Coatings Technology}, volume = {201}, year = {2006}, pages = {2977-2983}, chapter = {2977}, abstract = {

Thin films of tungsten oxynitrides were prepared by dual magnetron sputtering of tungsten using argon/oxygen/nitrogen gas mixtures with various nitrogen/oxygen ratios. The presence of even relatively small amounts of oxygen led to close-to-stoichiometric WO3, with little incorporation of nitrogen, therefore the films were labeled as WOx(Ny). Oxygen had a great effect not only on the composition but on the structure of WOx(Ny) films, as shown by Rutherford backscattering and X-ray diffraction, respectively. Significant incorporation of nitrogen occurred only when the nitrogen partial pressure exceeded 89\% of the total reactive gas pressure. Sharp changes in the stoichiometry, deposition rate, room temperature resistivity, electrical activation energy and optical band gap were observed when the nitrogen/oxygen ratio was high. The deposition rate increased from 0.31 to 0.89 nm/s, the room temperature resistivity decreased from 1.65 {\texttimes} 108 to 1.82 {\texttimes} 10- 2 Ω cm, the electrical activation energy decreased from 0.97 to 0.067 eV, and the optical band gap decreased from 3.19 to 2.94 eV upon nitrogen incorporation into the films. WOx(Ny) films were highly transparent as long as the nitrogen incorporation was low, and were brownish (absorbing) and partially reflecting as nitrogen incorporation became significant.

}, keywords = {Dual magnetron sputtering, electrical, optical properties, structural, tungsten oxynitride thin films}, doi = {10.1016/j.surfcoat.2006.06.008 }, author = {Sodky H. Mohamed and Andr{\'e} Anders} } @article {1861, title = {Subject Response to Electrochromic Windows}, journal = {Energy and Buildings}, volume = {38}, number = {7}, year = {2006}, month = {07/2006}, pages = {758-779}, chapter = {758}, abstract = {

Forty-three subjects worked in a private office with switchable electrochromic windows, manually-operated Venetian blinds, and dimmable fluorescent lights. The electrochromic window had a visible transmittance range of approximately 3-60\%. Analysis of subject responses and physical data collected during the work sessions showed that the electrochromic windows reduced the incidence of glare compared to working under a fixed transmittance (60\%) condition. Subjects used the Venetian blinds less often and preferred the variable transmittance condition, but used slightly more electric lighting with it than they did when window transmittance was fixed.

}, keywords = {Electrochromic windows, energy use, Subjective response, Venetian blind use}, doi = {10.1016/j.enbuild.2006.03.011}, author = {Robert D. Clear and Vorapat Inkarojrit and Eleanor S. Lee} } @techreport {58563, title = {Summary results of visual comfort measurements at the electrochromic windows testbed}, year = {2006}, note = {

Included as an attachment to the Advancement of Electrochromic Windows final report.

}, month = {03/2006}, address = {Berkeley}, abstract = {

The study was performed at the Lawrence Berkeley National Laboratory (LBNL) windows testbed in Berkeley California. The location is 37.4{\textdegree}N latitude. The maximum solar altitude ranges from approximately 29{\textdegree} to 76{\textdegree}, with a yearly average of about 53{\textdegree}. The testbed rooms have their windows mounted due south. The azimuthal angle at sunrise varies from approximately 60{\textdegree} from due south in the winter to 120{\textdegree} in summer. The analysis was restricted to the period from 6:00-18:00 standard time. Sunrise ranges from 4:42 to 7:17 (solar time), so the sun was not visible during part of the winter study periods.

}, author = {Robert D. Clear} } @techreport {1221, title = {Technical Note: The New York Times Demand Response Strategies for the HVAC System}, year = {2006}, author = {Flack + Kurtz} } @techreport {1980, title = {Window-Related Energy Consumption in the US Residential and Commercial Building Stock}, year = {2006}, abstract = {

We present a simple spreadsheet-based tool for estimating window-related energy consumption in the United States. Using available data on the properties of the installed US window stock, we estimate that windows are responsible for 2.15 quadrillion Btu (Quads) of heating energy consumption and 1.48 Quads of cooling energy consumption annually. We develop estimates of average U-factor and SHGC for current window sales. We estimate that a complete replacement of the installed window stock with these products would result in energy savings of approximately 1.2 quads. We demonstrate that future window technologies offer energy savings potentials of up to 3.9 Quads.

}, author = {Joshua S. Apte and Dariush K. Arasteh} } @conference {1988, title = {Zero Energy Windows}, booktitle = {2006 ACEEE Summer Study on Energy Efficiency in Buildings}, year = {2006}, month = {08/2006}, address = {Pacific Grove, CA}, abstract = {

Windows in the U.S. consume 30 percent of building heating and cooling energy, representing an annual impact of 4.1 quadrillion BTU (quads) of primary energy. Windows have an even larger impact on peak energy demand and on occupant comfort. An additional 1 quad of lighting energy could be saved if buildings employed effective daylighting strategies.

The ENERGY STAR(r) program has made standard windows significantly more efficient. However, even if all windows in the stock were replaced with today{\textquoteright}s efficient products, window energy consumption would still be approximately 2 quads. However, windows can be "net energy gainers" or "zero-energy" products. Highly insulating products in heating applications can admit more useful solar gain than the conductive energy lost through them. Dynamic glazings can modulate solar gains to minimize cooling energy needs and, in commercial buildings, allow daylighting to offset lighting requirements. The needed solutions vary with building type and climate. Developing this next generation of zero-energy windows will provide products for both existing buildings undergoing window replacements and products which are expected to be contributors to zero-energy buildings.

This paper defines the requirements for zero-energy windows. The technical potentials in terms of national energy savings and the research and development (R\&D) status of the following technologies are presented:

Market transformation policies to promote these technologies as they emerge into the marketplace are then described.

}, author = {Dariush K. Arasteh and Stephen E. Selkowitz and Joshua S. Apte and Marc LaFrance} } @mastersthesis {58225, title = {Balancing comfort: occupants{\textquoteright} control of window blinds in private offices}, year = {2005}, pages = {281}, school = {University of California, Berkeley}, type = {PhD}, address = {Berkeley}, abstract = {

The goal of this study was to develop predictive models of window blind control that could be used as a function in energy simulation programs and provide the basis for the development of future automated shading systems. Toward this goal, a two-part study, consisting of a window blind usage survey and a field study, was conducted in Berkeley, California, USA, during a period spanning from the vernal equinox to window solstice. A total of one hundred and thirteen office building occupants participated in the survey. Twenty-five occupants participated in the field study, in which measurements of physical environmental conditions were cross-linked to the participants{\textquoteright} assessment of visual and thermal comfort sensations.

Results from the survey showed that the primary window blind closing reason was to reduce glare from sunlight and bright windows. For the field study, a total of thirteen predictive window blind control logistic models were derived using the Generalized Estimating Equations (GEE) technique.

}, url = {http://escholarship.org/uc/item/3rd2f2bg}, author = {Vorapat Inkarojrit} } @article {11582, title = {Bi-Directional Transmission Properties of Venetian Blinds: Experimental Assessment Compared to Ray-Tracing Calculations}, journal = {Solar Energy}, volume = {78}, number = {2}, year = {2005}, pages = {187-198}, abstract = {

An accurate evaluation of daylight distribution through advanced fenestration systems (complex glazing, solar shading systems) requires the knowledge of their Bidirectional light Transmission (Reflection) Distribution Function BT(R)DF. An innovative equipment for the experimental assessment of these bi-directional functions has been developed, based on a digital imaging detection system. An extensive set of BTDF measurements was performed with this goniophotometer on Venetian blinds presenting curved slats with a mirror coating on the upper side. In this paper, the measured data are compared with ray-tracing results achieved with a virtual copy of the device, that was constructed with a commercial ray-tracing software. The model of the blind was created by implementing the measured reflection properties of the slats coatings in the ray-tracing calculations. These comparisons represent an original and objective validation methodology for detailed bi-directional properties for a complex system; the good agreement between the two methods, yet presenting very different parameters and assessment methodologies, places reliance both on the digital-imaging detection system and calibration, and on the potentiality of a flexible calculation method combining ray-tracing simulations with simple components measurements.

}, author = {Marilyn Andersen and Michael D. Rubin and Rebecca Powles and Jean-Louis Scartezzini} } @article {11682, title = {Daylighting control performance of a thin-film ceramic electrochromic window: Field study results}, journal = {Energy and Buildings}, volume = {38}, number = {4}, year = {2005}, pages = {30-44}, abstract = {

Control system development and lighting energy monitoring of ceramic thin-film electrochromic (EC) windows were initiated at the new full-scale Window Systems testbed facility at the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, California. The new facility consists of three identically configured side-by-side private offices with large-area windows that face due south. In one room, an array of EC windows with a center-of-glass visible transmittance (Tv) range of 0.05-0.60 was installed. In the two other rooms, unshaded windows with a Tv=0.50 or 0.15 were used as reference. The same dimmable fluorescent lighting system was used in all three rooms. This study explains the design and commissioning of an integrated EC window-lighting control system and then illustrates its performance in the testbed under clear, partly cloudy, and overcast sky conditions during the equinox period. The performance of an early prototype EC window controller is also analyzed. Lighting energy savings data are presented. Daily lighting energy savings were 44-59\% compared to the reference window of Tv=0.15 and 8-23\% compared to the reference window of Tv=0.50. The integrated window-lighting control system maintained interior illuminance levels to within ?10\% of the setpoint range of 510-700 lux for 89-99\% of the day. Further work is planned to refine the control algorithms and monitor cooling load, visual comfort, and human factor impacts of this emerging technology.

}, author = {Eleanor S. Lee and Dennis L. DiBartolomeo and Stephen E. Selkowitz} } @techreport {58284, title = {Daylighting the New York Times Headquarters Building: Final Report}, year = {2005}, month = {06/2005}, abstract = {

The technical energy-savings potential for smart integrated window-daylighting systems is excellent and can yield significant reductions in US commercial building energy use if adopted by a significant percentage of the market. However, conventional automated shades and daylighting controls have been commercially available for over two decades with less than 1-2\% market penetration in the US. As with all innovations, the problem with accelerating market adoption is one of decreasing risk. As the building owner researches technology options, the usual questions surface that concern the purchase of any new product: how will it work for my application, are the vendor claims valid, what risks are incurred, and will the performance benefits be sustained over the life of the installation? In their effort to create an environment that "enhances the way we work" in their new 139 km2 (1.5 Mft2) headquarters building in downtown Manhattan, The New York Times employed a unique approach to create a competitive marketplace for daylighting systems. A monitored field test formed the strategic cornerstone for accelerating an industry response to the building owners{\textquoteright} challenge to a sleepy market (i.e., US automated shading and daylighting control products have had few major technical advances over the past 10 years). Energy, control system, and environmental quality performance of commercially-available automated roller shade and daylighting control systems were evaluated. Procurement specifications were produced. Bids were received that met The Times cost-effective criteria. The Times will proceed with the use of these systems in their final building. Competitively-priced new products have been developed as a result of this research and are now available on the market.

}, keywords = {automated daylighting controls, automated window shades, daylighting, energy-efficiency, visual comfort}, author = {Eleanor S. Lee and Stephen E. Selkowitz and Glenn D. Hughes and Robert D. Clear and Gregory J. Ward and John Mardaljevic and Judy Lai and Mehlika Inanici and Vorapat Inkarojrit} } @conference {11697, title = {DElight2 Daylighting Analysis in Energy Plus: Integration and Preliminary User Results}, booktitle = {Building Simulation 2005}, year = {2005}, month = {08/2005}, address = {Montreal, Canada}, abstract = {

DElight is a simulation engine for daylight and electric lighting system analysis in buildings. DElight calculates interior illuminance levels from daylight, and the subsequent contribution required from electric lighting to meet a desired interior illuminance. DElight has been specifically designed to integrate with building thermal simulation tools. This paper updates the DElight capability set, the status of integration into the simulation tool EnergyPlus, and describes a sample analysis of a simple model from the user perspective.

}, author = {William L. Carroll and Robert J. Hitchcock} } @conference {58227, title = {Energetic or Not Energetic: Considerations for Fabricating Nanostructures by Physical Vapor Deposition}, booktitle = {NanoSingapore 2006: IEEE Conference on Emerging Technologies - Nanoelectrics, January 10-13}, year = {2005}, note = {

Presented as Invited Talk at
NanoSingapore 2006: IEEE Conference on Emerging Technologies {\textendash} Nanoelectronics
Singapore
January 10-13, 2006

}, month = {06/2005}, address = {Singapore}, abstract = {

Physical vapor deposition (PVD) has greatly matured in terms of growth modeling and equipment available. For this reason, and the often-required limitation to low-temperature processing, it is app ealing to utilize PVD methods not only for thin films but also for the synthesis of nanostructures. This is true even as many other methods enjoy the advantage of not needing high vacuum equipment.

PVD techniques are traditionally classified by the method of vapor generation, though here it is argued that a physically meaningful classification can be based on the energetics of film-forming species. At the low end of the energy scale, evaporation methods can be used to produce columnar structures with significant porosity. Sputtering at high pressure results in similar properties. This regime is preferred for sculptured structures, which involves moving tilted substrates (chiral films, chevrons, etc. [1]). As the energy is increased, so is the mobility of surface atoms, and we enter an energy regime that is widely used in thin film deposition by magnetron sputtering. Recently, high power pulsed sputtering has evolved as an energetic extension of conventional sputtering [2]. The enhanced degree of ionization enables the efficient application of bias techniques. Additionally, species seem to have higher kinetic energy. Ultimately, one would like to have fully ionized plasmas to fully exploit biasing, which can be done by using filtered cathodic arc plasmas [3]. Considering the high-energy range, substrates can be ion-treated by immersing them in a plasma and applying high voltage pulses, a technique known as plasma-based ion implantation.

Nanostructures are preferentially fabricated at either the low energy (\< 1 eV, e.g. for sculptured films) or very high energy (\> 1 keV, e.g. metal filling of lithographically produced nanotrenches [4], or formation of precipitates or bubbles by ion implantation [5]). At the intermediate energy range, ~ 100 eV, nanoscale processing of interfaces is used to obtain coatings with superior adhesion. Subplantation growth is facilitated at this energy, which is especially important for tuning the structure and properties of diamond-like carbon and a range of nitride and oxide materials.

}, author = {Andr{\'e} Anders} } @conference {11943, title = {The Impact of Overhang Designs on the Performance of Electrochromic Windows}, booktitle = {ISES 2005 Solar World Congress}, year = {2005}, month = {08/2005}, address = {Orlando, FL}, abstract = {

In this study, various facade designs with overhangs combined with electrochromic window control strategies were modeled with a prototypical commercial office building in a hot and cold climate using the DOE 2.1E building energy simulation program. Annual total energy use (ATE), peak electric demand (PED), average daylight illuminance (DI), and daylight glare index (DGI) were computed and compared to determine which combinations of fa{\c c}ade design and control strategies yielded the greatest energy efficiency, daylight amenity, and visual comfort.

}, author = {Aslihan Tavil and Eleanor S. Lee} } @article {1222, title = {Master of the House: Why a Company Should Take Control of Its Building Projects}, journal = {Harvard Business Review}, year = {2005}, month = {10/2005}, pages = {1-8}, publisher = {Harvard Business School Publishing Corporation}, url = {http://hbr.org/2005/10/master-of-the-house-why-a-company-should-take-control-of-its-building-projects/ar/1}, author = {David Thurm} } @article {12184, title = {Physics of Arcing, and Implications to Sputter Deposition}, journal = {Thin Solid Films}, year = {2005}, abstract = {

Arcing on sputter targets and negatively biased substrates is known as one of the most challenging issues in physical vapor deposition of thin films and coatings. This is particularly true when high-rate deposition with reactive gases, large area deposition, and high power pulsed sputtering are considered. Much progress has been made in the development of power supplies that can handle arcing events with minimal damage to target and substrate. However, relatively little is known about the processes leading to arcs and the physics of the arcing events themselves. In this contribution, the issue of arcing is approached from the point of view of arc physics. Current knowledge of arcing and arc suppression is reviewed.

(Note: PDF contains both LBNL-54220 \& LBNL-54220 Journal.)

}, author = {Andr{\'e} Anders} } @conference {12187, title = {Plasma and Ion Sources in Large Area Coatings: A Review}, year = {2005}, abstract = {

Efficient deposition of high-quality coatings often requires controlled application of excited or ionized particles. These particles are either condensing (film-forming) or assisting by providing energy and momentum to the film growth process, resulting in densification, sputtering/etching, modification of stress, roughness, texture, etc. In this review, the technical means are surveyed enabling large area application of ions and plasmas, with ion energies ranging from a few eV to a few keV. Both semiconductor-type large area (single wafer or batch processing with ~ 1000 cm2) and in-line web and glass-coating-type large area (\> 107 m2 annually) are considered. Characteristics and differences between plasma and ion sources are explained. The latter include gridded and gridless sources. Many examples are given, including sources based on DC, RF, and microwave discharges, some with special geometries like hollow cathodes and E x B configurations.

}, author = {Andr{\'e} Anders} } @article {12189, title = {Plasma-Based Ion Implantation and Deposition: A Review of Physics, Technology, and Applications}, journal = {IEEE Transactions on Plasma Science}, volume = {33}, number = {6}, year = {2005}, pages = {1944-1959}, abstract = {

After pioneering work in the 1980s, plasma-based ion implantation (PBII) and plasma-based ion implantation and deposition (PBIID) can now be considered mature technologies for surface modification and thin film deposition. This review starts by looking at the historical development and recalling the basic ideas of PBII. Advantages and disadvantages are compared to conventional ion beam implantation and physical vapor deposition for PBII and PBIID, respectively, followed by a summary of the physics of sheath dynamics, plasma and pulse specifications, plasma diagnostics, and process modelling. The review moves on to technology considerations for plasma sources and process reactors. PBII surface modification and PBIID coatings are applied in a wide range of situations. They include the by-now traditional tribological applications of reducing wear and corrosion through the formation of hard, tough, smooth, low-friction and chemically inert phases and coatings, e.g. for engine components. PBII has become viable for the formation of shallow junctions and other applications in microelectronics. More recently, the rapidly growing field of biomaterial synthesis makes used of PBII\&D to produce surgical implants, bio- and blood-compatible surfaces and coatings, etc. With limitations, also non-conducting materials such as plastic sheets can be treated. The major interest in PBII processing originates from its flexibility in ion energy (from a few eV up to about 100 keV), and the capability to efficiently treat, or deposit on, large areas, and (within limits) to process non-flat, three-dimensional workpieces, including forming and modifying metastable phases and nanostructures. We use the acronym PBII\&D when referring to both implantation and deposition, while PBIID implies that deposition is part of the process.

}, author = {Jacques Pelletier and Andr{\'e} Anders} } @techreport {1768, title = {RESFEN5: Program Description}, year = {2005}, month = {05/2005}, institution = {Lawrence Berkeley National Laboratory}, abstract = {

A computer tool such as RESFEN can help consumers and builders pick the most energy-efficient and cost-effective window for a given application, whether it is a new home, an addition, or a window replacement. It calculates heating and cooling energy use and associated costs as well as peak heating and cooling demand for specific window products. Users define a specific scenario by specifying house type (single-story or two-story), geographic location, orientation, electricity and gas cost, and building configuration details (such as wall, floor, and HVAC system type). Users also specify size, shading, and thermal properties of the window they wish to investigate. The thermal properties that RESFEN requires are: U-factor, Solar Heat Gain Coefficient, and air leakage rate. RESFEN calculates the energy and cost implications of the window compared to an insulated wall. The relative energy and cost impacts of two different windows can be compared.

RESFEN 3.0 was a major improvement over previous versions because it performs hourly calculations using a version of the DOE 2.1E (LBL 1980, Winkelmann et al. 1993) energy analysis simulation program. RESFEN 3.1 incorporates additional improvements including input assumptions for the base case buildings taken from the National Fenestration Rating Council (NFRC) Annual Energy Subcommittee{\textquoteright}s efforts.

}, author = {Robin Mitchell and Yu Joe Huang and Dariush K. Arasteh and Charlie Huizenga and Steve Glendenning} } @conference {1934, title = {Two-Dimension Conduction and CFD Simulations for Heat Transfer in Horizontal Window Frame Cavities}, booktitle = {2005 ASHRAE Winter Meeting}, volume = {111}, year = {2005}, month = {02/2005}, address = {Orlando, FL}, abstract = {

Accurately analyzing heat transfer in window frames and glazings is important for developing and characterizing the performance of highly insulating window products. This paper uses computational fluid dynamics (CFD) modeling to assess the accuracy of the simplified frame cavity conduction/convection models presented in ISO 15099 and used in software for rating and labeling window products. Three representative complex cavity cross-section profiles with varying dimensions and aspect ratios are examined. The results presented support the ISO 15099 rule that complex cavities with small throats should be subdivided; however, our data suggest that cavities with throats smaller than 7 mm should be subdivided, in contrast to the ISO 15099 rule, which places the break point at 5 mm. The agreement between CFD modeling results and the results of the simplified models is moderate for the heat transfer rates through the cavities. The differences may be a result of the underlying ISO 15099 Nusselt number correlations being based on studies where cavity height/length aspect ratios were smaller than 0.5 and greater than 5 (with linear interpolation assumed in between). The results presented here are for horizontal frame members because convection in vertical jambs involves very different aspect ratios that require three-dimensional CFD simulations.

}, author = {Arlid Gustavsen and Dariush K. Arasteh and Christian Kohler and Dragan C. Curcija} } @booklet {1223, title = {Analysis of visual comfort using high-dynamic-range luminance images}, year = {2004}, author = {Vorapat Inkarojrit} } @article {11614, title = {Charge-State-Resolved Ion Energy Distributions of Aluminum Vacuum Arcs}, journal = {Journal of Applied Physics}, volume = {97}, number = {10}, year = {2004}, abstract = {

The charge-state-resolved ion energy distributions of metal ions present in a cathodic arc plasma have been measured and analyzed. Contrary to literature data, lower energies were observed for higher charged ions. The observations were explained by opposing acceleration by pressure gradient and electron-ion coupling, and deceleration by part of the discharge voltage. The distributions were well fitted by shifted Maxwellian distributions, giving additional information on plasma parameters. These results are of importance for an improved understanding of the evolution of ion energy distributions, and is hence instrumental for future progress in thin film growth modelling.

}, author = {Johanna Ros{\'e}n and Andr{\'e} Anders and Stanislav Mr{\'a}z and Jochen M. Schneider} } @conference {11745, title = {Development of Trade-Off Equations for EnergyStar Windows}, booktitle = {SimBuild 2004}, year = {2004}, month = {08/2004}, address = {Boulder, CO}, abstract = {

The authors explore the feasibility of adding a performance option to DOE{\textquoteright}s EnergyStar{\textcopyright} Windows program whereby windows of differing U-factors and SHGCs can qualify so long as they have equivalent annual energy performance. An iterative simulation procedure is used to calculate trade-off equations giving the change in SHGC needed to compensate for a change in U-factor. Of the four EnergyStar{\textcopyright} Window climate zones, trade-off equations are possible only in the Northern and Southern zones. In the North/Central and South/Central zones, equations are not possible either because of large intrazone climate variations or the current SHGC requirements are already near optimum.

}, author = {Yu Joe Huang and Robin Mitchell and Stephen E. Selkowitz and Dariush K. Arasteh and Robert D. Clear} } @article {11768, title = {Effect of Ion Mass and Charge State on Transport Vacuum Arc Plasmas Through a Biased Magnetic Filter}, journal = {IEEE Transactions on Plasma Science}, volume = {32}, number = {2}, year = {2004}, month = {04/2004}, pages = {433-439}, chapter = {433}, abstract = {

The effect of ion mass and charge state on plasma transport through a 90 deg.-curved magnetic filter is experimentally investigated using a pulsed cathodic arc source. Graphite, copper, and tungsten were selected as test materials. The filter was a bent copper coil biased via the voltage drop across a low-ohm, selfbias resistor. Ion transport is accomplished via a guiding electric field, whose potential forms a trough shaped by the magnetic guiding field of the filter coil. Evaluation was done by measuring the filtered ion current and determination of the particle system coefficient, which can be defined as the ratio of filtered ion current, divided by the mean ion charge state, to the arc current. It was found that the ion current and particle system coefficient decreased as the mass-to-charge ratio of ions increased. This result can be qualitatively interpreted by a very simple model of ion transport that is based on compensation of the centrifugal force by the electric force associated with the guiding potential trough.

}, keywords = {Arc plasma, cathodic vacuum arc, ion charge states, macroparticle filter, plasma transport}, issn = {0093-3813 }, doi = {10.1109/TPS.2004.826363}, author = {Eungsun Byon and Jong-Kuk Kim and Sik-Chol Kwon and Andr{\'e} Anders} } @techreport {1386, title = {The Energy-Savings Potential of Electrochromic Windows in the US Commercial Buildings Sector}, year = {2004}, abstract = {

Switchable electrochromic (EC) windows have been projected to significantly reduce the energy use of buildings nationwide. This study quantifies the potential impact of electrochromic windows on US primary energy use in the commercial building sector and also provides a broader database of energy use and peak demand savings for perimeter zones than that given in previous LBNL simulation studies. The DOE-2.1E building simulation program was used to predict the annual energy use of a three-story prototypical commercial office building located in five US climates and 16 California climate zones. The energy performance of an electrochromic window controlled to maintain daylight illuminance at a prescribed setpoint level is compared to conventional and the best available commercial windows as well as windows defined by the ASHRAE 90.1-1999 and California Title 24-2005 Prescriptive Standards. Perimeter zone energy use and peak demand savings data by orientation, window size, and climate are given for windows with interior shading, attached shading, and horizon obstructions (to simulate an urban environment).

Perimeter zone primary energy use is reduced by 10-20\% in east, south, and west zones in most climates if the commercial building has a large window-to-wall area ratio of 0.60 compared to a spectrally selective low-e window with daylighting controls and no interior or exterior shading. Peak demand for the same condition is reduced by 20-30\%. The emerging electrochromic window with daylighting controls is projected to save approximately 91.5-97.3 1012 Btu in the year 2030 compared to a spectrally selective low-E window with manually-controlled interior shades and no daylighting controls if it reaches a 40\% market penetration level in that year.

}, author = {Eleanor S. Lee and Mehry Yazdanian and Stephen E. Selkowitz} } @techreport {1400, title = {Evaluation of High Dynamic Range Photography as a Luminance Mapping Technique}, year = {2004}, abstract = {

The potential, limitations, and applicability of the High Dynamic Range (HDR) photography technique is evaluated as a luminance mapping tool. Multiple exposure photographs of static scenes are taken with a Nikon 5400 digital camera to capture the wide luminance variation within the scenes. The camera response function is computationally derived using the Photosphere software, and is used to fuse the multiple photographs into HDR images. The vignetting effect and point spread function of the camera and lens system is determined. Laboratory and field studies have shown that the pixel values in the HDR photographs can correspond to the physical quantity of luminance with reasonable precision and repeatability.

}, author = {Mehlika Inanici and Jim Galvin} } @techreport {1428, title = {A First-Generation Prototype Dynamic Residential Window}, year = {2004}, month = {10/2004}, pages = {11}, abstract = {

We present the concept for a "smart" highly efficient dynamic window that maximizes solar heat gain during the heating season and minimizes solar heat gain during the cooling season in residential buildings. We describe a prototype dynamic window that relies on an internal shade, which deploys automatically in response to solar radiation and temperature. This prototype was built at Lawrence Berkeley National Laboratory from commercially available "off-the-shelf" components. It is a stand-alone, standard-size product, so it can be easily installed in place of standard window products. Our design shows promise for near-term commercialization. Improving thermal performance of this prototype by incorporating commercially available highly efficient glazing technologies could result in the first window that could be suitable for use in zero-energy homes. The units predictable deployment of shading could help capture energy savings that are not possible with manual shading. Installation of dynamically shaded windows in the field will allow researchers to better quantify the energy effects of shades, which could lead to increased efficiency in the sizing of heating, ventilation, and air conditioning equipment for residences.

}, author = {Christian Kohler and Howdy Goudey and Dariush K. Arasteh} } @conference {11989, title = {Integrating Automated Shading and Smart Glazings with Daylight Controls}, booktitle = {International Symposium on Daylighting Buildings}, year = {2004}, month = {03/2004}, pages = {B13-B20}, address = {Tokyo, Japan}, abstract = {

Most commercial buildings utilize windows and other glazed envelope components for a variety of reasons. Glass is a key element in the architectural expression of the building and typically provides occupants with a visual connection with the outdoors and daylight to enhance the quality of the indoor environment. But the building skin must serve a crucial function in its role to help maintain proper interior working environments under extremes of external environmental conditions. Exterior temperature conditions vary slowly over a wide range and solar and daylight fluxes can vary very rapidly over a very wide range. The technical problem of controlling heat loss and gain is largely solved with highly insulating glazing technologies on the market today. The challenge of controlling solar gain and managing daylight, view and glare is at a much earlier stage. In most cases a static, fixed control solution will not suffice. Some degree of active, rapid response to changing outdoor conditions and to changing interior task requirements is needed. This can be provided with technology within the glass or glazing assembly itself, or the functionality can be added to the facade either on the interior or exterior of the glazing. In all cases sensors, actuators, and a control logic must be applied for proper functionality. Traditional manually operated mechanical shading systems such as blinds or shades can be motorized and then controlled by occupant action or by sensors and building controls. Emerging smart glass technology can dynamically change optical properties, and can be activated manually or by automated control systems. In all of these cases electric lighting should be controlled to meet occupant needs, while maximizing energy efficiency and minimizing electric demand. As with the fenestration controls, lighting control requires sensors (photocells or the human eye), actuation (switching or dimming) and a control logic that determines what action should be taken under each set of conditions. Some variation on the combination of all of these elements comprises the typical equipment and systems found in most commercial buildings today. The new challenge is to provide a fully functional and integrated facade and lighting system that operates appropriately for all environmental conditions and meets a range of occupant subjective desires and International Symposium on objective performance requirements. And finally these rigorous performance goals must be achieved with solutions that are cost effective and operate over long periods with minimal maintenance.

}, author = {Stephen E. Selkowitz and Eleanor S. Lee} } @article {12036, title = {Low-Cost Networking for Dynamic Window Systems}, journal = {Energy and Buildings}, volume = {36}, number = {6}, year = {2004}, pages = {503-513}, abstract = {

A low-cost building communications network is needed that would allow individual window and lighting loads to be controlled fromsan existing enterprise LAN network. This building communications network concept, which we term Integrated Building EnvironmentalsCommunications System (IBECSTM), would enable both occupant-based and building-wide control of individual window, lighting, andssensor devices. IBECS can reduce the cost of systemic control because it allows a drastic cost reduction in per point networking costs. This kind of effort is needed to encourage the control industry to make the commitment to build this technology and to demonstratesto prospective customers that this breakthrough approach to more comprehensive systemic control will provide them with high-quality,sconvenient control while saving them money.

The development and demonstration of network interfaces to DC- and AC-motorized shades and to an electrochromic window aresdescribed. The network interfaces enable one to control and monitor the condition of these fenestration appliances from a variety of sources,sincluding a user?s personal computer. By creating a functional specification for an IBECS network interface and testing a prototype, thesability to construct such an interface was demonstrated and the cost-effective price per point better understood. The network interfacesswere demonstrated to be reliable in a full-scale test of three DC-motorized Venetian blinds in an open-plan office over 2 years and in limitedsbench-scale tests of an electrochromic window.

}, author = {Eleanor S. Lee and Dennis L. DiBartolomeo and Francis M. Rubinstein and Stephen E. Selkowitz} } @conference {12049, title = {Market Transformation Opportunities for Emerging Dynamic Facade and Dimmable Lighting Control Systems}, booktitle = {2004 ACEEE Summer Study on Energy Efficiency in Buildings}, year = {2004}, month = {08/2004}, address = {Pacific Grove, CA}, abstract = {

Automated shading and daylighting control systems have been commercially available for decades. The new challenge is to provide a fully functional and integrated facade and lighting system that operates appropriately for all environmental conditions and meets a range of occupant subjective desires and objective performance requirements. These rigorous performance goals must be achieved with solutions that are cost effective and can operate over long periods with minimal maintenance. It will take time and effort to change the marketplace for these technologies and practices, particularly in building a series of documented success stories, and driving costs and risks to much lower levels at which their use becomes the norm. In recent years, the architectural trend toward highly-transparent all-glass buildings presents a unique challenge and opportunity to advance the market for emerging, smart, dynamic window and dimmable daylighting control technologies.

We believe it is possible to accelerate product market transformation by developing projects where technical advances and the interests of motivated manufacturers and innovative owners converge. In this paper we present a case study example that explains a building owners decision-making process to use dynamic window and dimmable daylighting controls. The case study project undertaken by a major building owner in partnership with a buildings R\&D group was designed explicitly to use field test data in conjunction with the market influence of a major landmark building project in New York City to stimulate change in manufacturers product offerings. Preliminary observations on the performance of these systems are made. A cost model that was developed with the building owner is explained.

}, author = {Eleanor S. Lee and Stephen E. Selkowitz and Glenn D. Hughes and David A. Thurm} } @article {12122, title = {Observation of Self-Sputtering in Energetic Condensation of Metal Ions}, journal = {Applied Physics Letters}, volume = {85}, number = {25}, year = {2004}, pages = {6137-6139}, abstract = {

The condensation of energetic metal ions on a surface may cause self-sputtering even in the absence of substrate bias. Charge-state-averaged self-sputtering yields were determined for both zirconium and gold ions generated by a cathodic vacuum arc. Films were deposited on differently biased substrates exposed to streaming Zr and Au vacuum arc plasma. The self-sputtering yields for both metals were estimated to be about 0.05 in the absence of bias, and exceeding 0.5 when bias reached - 50 V. These surprisingly high values can be reconciled with binary collision theory and molecular dynamics calculations taking high the kinetic and potential energy of vacuum arc ions into account.

}, author = {Andr{\'e} Anders} } @article {1912, title = {Time-Dependence of Ion Charge State Distributions of Vacuum Arcs: An Interpretation Involving Atoms and Charge Exchange Collisions}, journal = {IEEE Transactions on Plasma Science}, volume = {33}, number = {1}, year = {2004}, pages = {205-209}, abstract = {

Experimentally observed charge state distributions are known to be higher at the beginning of each arc discharge. Up to know, this has been attributed to cathode surface effects in terms of changes of temperature, chemical composition and spot mode. Here it is shown that the initial decay of charge states of cathodic arc plasmas may at least in part due to charge exchange collisions of ions with neutrals that gradually fill the discharge volume. Sources of neutrals may include evaporated atoms from macroparticles and still-hot craters of previously active arc spots. More importantly, atoms are also produced by energetic condensation of the cathodic arc plasma. Self-sputtering is significant when ions impact with near-normal angle of incidence, and ions have low sticking probability when impacting at oblique angle of incidence. Estimates show that the characteristic time for filling the near-cathode discharge volume agrees well with the charge state decay time, and the likelihood of charge exchange is reasonably large to be taken into account.

}, author = {Andr{\'e} Anders} } @book {58586, title = {Window Systems for High-Performance Buildings}, year = {2004}, month = {04/2004}, pages = {400}, publisher = {W. W. Norton \& Company, Inc.,}, organization = {W. W. Norton \& Company, Inc.,}, address = {New York, NY}, abstract = {

A guide to essential window design issues, technologies, and applications for designers, specifiers, and builders.

The challenge in designing facades and selecting windows in commercial buildings is balancing many issues and criteria. This fact-packed guide outlines the basics of glazing selection and provides critical information and performance data on the energy efficiency, interior environment, technical, and life-cycle-cost considerations that drive window design decisions in commercial buildings.

}, isbn = {978-0-393-73121-7}, issn = {0198711956}, author = {John Carmody and Stephen E. Selkowitz and Eleanor S. Lee and Dariush K. Arasteh} } @conference {58238, title = {Advanced Interactive Fa{\c c}ades {\textemdash} Critical Elements for Future Green Buildings?}, booktitle = {GreenBuild, the annual USGBC International Conference and Expo}, year = {2003}, month = {11/2013}, abstract = {

Building designers and owners have always been fascinated with the extensive use of glass in building envelopes. Today the highly glazed fa{\c c}ade has almost become an iconic element for a "green building" that provides daylighting and a visual connection with the natural environment. Even before the current interest in green buildings there was no shortage of highly glazed building designs. But many of these buildings either rejected sunlight, and some associated daylight and view with highly reflective glazings or used highly transmissive glass and encountered serious internal comfort problems that could only be overcome with large HVAC systems, resulting in significant energy, cost and environmental penalties.

}, author = {Stephen E. Selkowitz and {\O}yvind Aschehoug and Eleanor S. Lee} } @article {11626, title = {Coalescence of Nanometer Silver Islands on Oxides Grown by Filtered Cathodic Arc Deposition}, journal = {Applied Physics Letters}, volume = {82}, number = {10}, year = {2003}, pages = {1634-1636}, chapter = {1634}, abstract = {

Ultrathin silver films have been deposited on glass and oxide-coated glass using filtered cathodic arc deposition and, for comparison, magnetron sputtering. The energetic differences between these deposition methods lead to initially different film properties. Silver films made by cathodic arc deposition show an earlier onset of island coalescence, indicating a lower aspect ratio than islands produced by evaporation and sputtering. However, the as-deposited films are thermodynamically unstable, exhibiting changes on a timescale of minutes. While films of islands tend to increase their sheet resistance with time, the sheet resistance of contiguous films shows a decrease. Both effects can be explained by silver mobility driven to minimize film and interfacial energy.

}, url = {http://dx.doi.org/10.1063/1.1558955}, author = {Eungsun Byon and Thomas W.H. Oates and Andr{\'e} Anders} } @article {11635, title = {Comparison Between Ray-Tracing Simulations and Bi-Directional Transmission Measurements on Prismatic Glazing}, journal = {Solar Energy}, volume = {74}, number = {2}, year = {2003}, month = {02/2003}, pages = {157-173}, chapter = {157}, abstract = {

Evaluation of solar heat gain and daylight distribution through complex window and shading systems requires the determination of the bi-directional transmission distribution function (BTDF). Measurement of BTDF can be timeconsuming, and inaccuracies are likely because of physical constraints and experimental adjustments. A general calculation methodology, based on more easily measurable component properties, would be preferable and would allow much more flexibility. In this paper, measurements and calculations are compared for the specific case of prismatic daylight-redirecting panels. Measurements were performed in a photogoniometer equipped with a digital-imaging detection system. A virtual copy of the photogoniometer was then constructed with commercial ray-tracing software. For the first time, an attempt is made to validate detailed bi-directional properties for a complex system by comparing an extensive set of experimental BTDF data with ray-tracing calculations. The results generally agree under a range of input and output angles to a degree adequate for evaluation of glazing systems. An analysis is presented to show that the simultaneously measured diffuse and direct components of light transmitted by the panel are properly represented. Calculations were also performed using a more realistic model of the source and ideal model of the detector. Deviations from the photogoniometer model were small and the results were similar in form. Despite the lack of an absolute measurement standard, the good agreement in results promotes confidence in both the photogoniometer and in the calculation method.\ 

}, doi = {10.1016/S0038-092X(03)00115-4}, author = {Marilyn Andersen and Michael D. Rubin and Jean-Louis Scartezzini} } @conference {11773, title = {Effect of Underlayer on Coalescence of Silver Islands Grown by Filtered Cathodic Arc Deposition}, booktitle = {The International Conference on Metallurgical Coatings and Thin Films (ICMCTF 2003)}, year = {2003}, month = {05/2003}, address = {San Diego}, abstract = {

Ultrathin silver films that are not continuous show relatively high absorption in the visible and low reflection in the infrared. For low-emissivity application on window glass, coalescence of silver islands is crucial for obtaining the desired optical properties of the coating, namely high transparence in the visible and high reflectivity in the infrared. It is well known that the energy of ions arriving at the substrate and the type of underlayer affect nucleation and growth of silver islands. There are a number of studies on nucleation and growth, but little is known about coalescence of silver islands synthesized by more energetic condensation, e.g. filtered cathodic vacuum arc (FCVA). In this work, the effect of underlayer on nucleation and growth of silver films deposited by FCVA was investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The results arescompared with data obtained by magnetron sputtering.

From the results, plane and titanium-oxide-coated glass requires more material to achieve the same value of resistance than for the zinc oxide coated glass. It is related with the energy of interaction between the surface and the silver atom. Silver films made by cathodic arc deposition show an earlier onset of island coalescence and formation of short links. It was found that silver islands in energetic deposition exhibit a reduced aspect ratio when compared to evaporation and sputtering. Nb underlayer affects nucleation and growth of coalescence of silver only in the case of few monolayer of Nb was introduced.

}, author = {Eungsun Byon and Andr{\'e} Anders} } @article {11892, title = {Fundamentals of Pulsed Plasmas for Materials Processing}, journal = {Surface and Coatings Technology}, volume = {183}, number = {3-Feb}, year = {2003}, pages = {301-311}, abstract = {

Pulsed plasmas offer the use of much higher power (during each pulse) compared to continuously operated plasmas, and additional new parameters appear such as pulse duty cycle. Pulsed processing may help meeting the demands of increasingly sophisticated materials processes, including thin film deposition, plasma etching, plasma cleaning of surfaces, and plasma immersion ion implantation. The high kinetic energy of ions allows processes to occur far from thermodynamic equilibrium. Pulsed plasmas are driven by external pulsed power sources, and one has to consider the power source and the plasma as a coupled system. The dynamic plasma impedance is a key quantity from an electrical engineering point of view. From a plasma physics point of view, one needs to consider the dynamics of plasma species, their density and energy distribution, ionization and recombination reactions, and, most importantly, the development of transient sheaths. Dimensionless scaling parameters are a useful tool putting the variety of plasma parameters in relation to characteristic quantities. This is illustrated by several examples of pulsed processes relevant to thin film deposition. The emerging technology of pulsed sputtering is discussed in detail including the possibility to achieve the mode of self-sustained self-sputtering during each pulse.

}, author = {Andr{\'e} Anders} } @conference {12035, title = {Lithium-Based Electrochromic Mirrors}, booktitle = {203rd Meeting of the Electrochemical Society}, year = {2003}, month = {04/2003}, address = {Paris, France}, abstract = {

Antimony, antimony-copper, and antimony-silver thin films were prepared by DC magnetron sputtering on glass substrates. Their reflectance and transmittance in the visible range were measured before and after electrochemical lithiation. The mixed metal films exhibited larger changes in reflectance and small shifts in the optical absorption edge compared with pure antimony films. Electrochromic cycling speed and stability of the Sb-Li system were improved by the addition of copper and silver.

}, author = {Thomas J. Richardson and Jonathan L. Slack} } @conference {58262, title = {Perspectives on Advanced Fa{\c c}ades with Dynamic Glazings and Integrated Lighting Controls}, booktitle = {CISBAT 2003, Innovation in Building Envelopes and Environmental Systems, International Conferences on Solar Energy in Buildings}, year = {2003}, month = {10/2003}, address = {Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland}, abstract = {

There is growing interest in North America on the subject of highly glazed building fa{\c c}ades. The concept of a smart, interactive fa{\c c}ade is not new {\textendash} the ability of specific fa{\c c}ade systems to work reliably and effectively is a far greater challenge. We have been exploring various dynamic fa{\c c}ade systems with integrated lighting and HVAC over the last 10 years. These include automated blind systems as well as emerging electrochromic glazings, both with automated dimmable lighting and smart controls. More recently we have extended this work to include internet-based control of lights, blinds and glazings using low cost chips embedded in fixtures, motors, and glazing controls. As each window and lighting element becomes a node on the internet they can be controlled via the existing building energy management system either from an occupants desktop computer, an on-site facility manager or even from a remote location. Recent experience in California with disruptions in electric supply and costly peak power suggest value for such capabilities. This paper briefly summaries the state of recent work in this field, describing a new facility with three side-by-side test rooms in Berkeley to test new electrochromic window prototypes, and identifies key performance, systems integration and cost issues now being studied. The authors bring a cross section of both North American and European experience to address the many technology, design and business issues involved.

}, author = {Stephen E. Selkowitz and Eleanor S. Lee and {\O}yvind Aschehoug} } @conference {12183, title = {Physics of Arcing, and Implications to Sputter Deposition}, booktitle = {International Conference on Coatings on Glass}, year = {2003}, month = {07/2004}, address = {Saarbrucken, Germany}, abstract = {

Arc and glow discharges are defined based on their cathode processes. Arcs are characterized by collective electron emission, which can be stationary with hot cathodes (thermionic arcs), or nonstationary with cold cathodes (cathodic arcs). A brief review on cathodic arc properties serves as the starting point to better understand arcing phenomena in sputtering. Although arcing occurs in both metal and reactive sputtering, it is more of an issue in the reactive case. Arcing occurs if sufficiently high field strength leads to thermal runaway of an electron emission site. The role of insulating layers and surface potential adjustment through current leakage is highlighted. In the situation of magnetron sputtering with racetrack, the need for a model with two spatial dimensions is shown. In many cases, arcing is initiated by breakdown of dielectric layers and inclusions. It is most efficiently prevented if formation and excessive charge-up of dielectric layers and inclusions can be avoided.

(Note: PDF contains both LBNL-54220 \& LBNL-54220 Journal.)

}, author = {Andr{\'e} Anders} } @conference {1871, title = {Surface Engineering of Glazing Materials and Structures Using Plasma Processes}, booktitle = {Glass Processing Days 2003 }, year = {2003}, month = {06/2003}, address = {Tampere, Finland}, abstract = {

A variety of coatings is commercially produced on a very large scale, including transparent conducting oxides and multi-layer silver-based low-emissivity and solar control coatings. A very brief review of materials and manufacturing process is presented and illustrated by ultrathin silver films and chevron copper films. Understanding the close relation between manufacturing processes and bulk and surface properties of materials is crucial for film growth and self-assembly processes.

}, keywords = {nano-structures, plasma processing, surface engineering, thin films}, author = {Andr{\'e} Anders and Othon R. Monteiro} } @techreport {1894, title = {THERM 5/WINDOW 5 NFRC Simulation Manual}, year = {2003}, abstract = {

This document, the THERM 5 / WINDOW 5 NFRC Simulation Manual, discusses how to use the THERM and WINDOW programs to model products for NFRC certified simulations and assumes that the user is already familiar with those programs. In order to learn how to use these programs, it is necessary to become familiar with the material in both the THERM Users Manual and the WINDOW Users Manual. In general, this manual references the Users Manuals rather than repeating the information.

If there is a conflict between either of the User Manual and this THERM 5 / WINDOW 5 NFRC Simulation Manual, the THERM 5 / WINDOW 5 NFRC Simulation Manual takes precedence. In addition, if this manual is in conflict with any NFRC standards, the standards take precedence. For example, if samples in this manual do not follow the current taping and testing NFRC standards, the standards not the samples in this manual, take precedence.

}, author = {Robin Mitchell and Christian Kohler and Dariush K. Arasteh and John Carmody and Charlie Huizenga and Dragan C. Curcija} } @conference {1936, title = {Two-Dimensional Computational Fluid Dynamics and Conduction Simulations of Heat Transfer in Window Frames with Internal Cavities - Part 1: Cavities Only}, booktitle = {ASHRAE Winter Meeting}, year = {2003}, month = {02/2005}, address = {Orlando, FL}, abstract = {

Accurately analyzing heat transfer in window frame cavities is essential for developing and characterizing the performance of highly insulating window products. Window frame thermal performance strongly influences overall product thermal performance because framing materials generally perform much more poorly than glazing materials. This paper uses Computational Fluid Dynamics (CFD) modeling to assess the accuracy of the simplified frame cavity conduction/convection models presented in ISO 15099 and used in software for rating and labeling window products. (We do not address radiation heat-transfer effects.) We examine three representative complex cavity cross-section profiles with varying dimensions and aspect ratios. Our results support the ISO 15099 rule that complex cavities with small throats should be subdivided; however, our data suggest that cavities with throats smaller than seven millimeters (mm) should be subdivided, in contrast to the ISO 15099 rule, which places the break point at five mm. The agreement between CFD modeling results and the results of the simplified models is moderate. The differences in results may be a result of the underlying ISO correlations being based on studies where cavity height/length (H/L) aspect ratios were smaller than 0.5 and greater than five (with linear interpolation assumed in between). The results presented here are for horizontal frame members because convection in vertical jambs involves very different aspect ratios that require three-dimensional CFD simulations. Ongoing work focuses on quantifying the exact effect on window thermal performance indicators of using the ISO 15099 approximations in typical real window frames.

}, author = {Arlid Gustavsen and Christian Kohler and Dariush K. Arasteh and Dragan C. Curcija} } @conference {11515, title = {Active Load Management with Advanced Window Wall Systems: Research and Industry Perspectives}, booktitle = {ACEEE 2002 Summer Study on Energy Efficiency in Buildings: Teaming for Efficency}, year = {2002}, month = {08/2002}, address = {Pacific Grove, CA}, abstract = {

Advanced window wall systems have the potential to provide demand response by reducing peak electric loads by 20-30\% in many commercial buildings through the active control of motorized shading systems, switchable window coatings, operable windows, and ventilated double-skin facade systems. These window strategies involve balancing daylighting and solar heat gains, heat rejection through ventilation, and night-time natural ventilation to achieve space-conditioning and lighting energy use reductions without the negative impacts on occupants associated with other demand responsive (DR) strategies.

This paper explores conceptually how advanced window systems fit into the context of active load management programs, which cause customers to directly experience the time-varying costs of their consumption decisions. Technological options are suggested. We present pragmatic criteria that building owners use to determine whether to deploy such strategies. A utility{\textquoteright}s perspective is given. Industry also provides their perspectives on where the technology is today and what needs to happen to implement such strategies more broadly in the US.

While there is significant potential for these advanced window concepts, widespread deployment is unlikely to occur with business-as-usual practice. Technologically, integrated window-lighting-HVAC products are underdeveloped. Implementation is hindered by fragmented labor practices, non-standard communication protocols, and lack of technical expertise. Design tools and information products that quantify energy performance, occupant impacts, reliability, and other pragmatic concerns are not available. Interest within the building industry in sustainability, energy-efficiency, and increased occupant amenity, comfort, and productivity will be the driving factors for these advanced facades in the near term {\textemdash} at least until the dust settles on the deregulated electricity market.

}, author = {Eleanor S. Lee and Stephen E. Selkowitz and Mark S. Levi and Steven L. Blanc and Erin McConahey and Maurya McClintock and Pekka Hakkarainen and Neil L. Sbar and Michael P. Myser} } @article {30021, title = {Application issues for large-area electrochromic windows in commercial buildings}, journal = {Solar Energy Materials and Solar Cells}, volume = {71}, year = {2002}, month = {03/2002}, pages = {465{\textendash}491}, abstract = {

Projections of performance from small-area devices to large-area windows and enterprise marketing have created high expectations for electrochromic glazings. As a result, this paper seeks to precipitate an objective dialog between material scientists and building-application scientists to determine whether actual large-area electrochromic devices will result in significant performance benefits and what material improvements are needed, if any, to make electrochromics more practical for commercial building applications. Few in situ tests have been conducted with large-area electrochromic windows applied in buildings. This study presents monitored results from a full-scale field test of large-area electrochromic windows to illustrate how this technology will perform in commercial buildings. The visible transmittance (T v ) of the installed electrochromic ranged from 0.11 to 0.38. The data are limited to the winter period for a south-east-facing window. The effect of actual device performance on lighting energy use, direct sun control, discomfort glare, and interior illumination is discussed. No mechanical system loads were monitored. These data demonstrate the use of electrochromics in a moderate climate and focus on the most restrictive visual task: computer use in offices. Through this small demonstration, we were able to determine that electrochromic windows can indeed provide unmitigated transparent views and a level of dynamic illumination control never before seen in architectural glazing materials. Daily lighting energy use was 6-24\% less compared to the 11\%-glazing, with improved interior brightness levels. Daily lighting energy use was 3\% less to 13\% more compared to the 38\%-glazing, with improved window brightness control. The electrochromic window may not be able to fulfill both energy-efficiency and visual comfort objectives when low winter direct sun is present, particularly for computer tasks using cathode-ray tube (CRT) displays. However, window and architectural design as well as electrochromic control options are suggested as methods to broaden the applicability of electrochromics for commercial buildings. Without further modification, its applicability is expected to be limited during cold winter periods due to its slow switching speed. {\textcopyright} 2002 Elsevier Science B.V. All rights reserved.

}, issn = {0927-0248}, doi = {10.1016/S0927-0248(01)00101-5}, author = {Eleanor S. Lee and Dennis L. DiBartolomeo} } @article {11583, title = {Bias and Self-Bias of Magnetic Macroparticle Filters for Cathodic Arc Plasmas}, journal = {Journal of Applied Physics}, volume = {93}, number = {11}, year = {2002}, pages = {8890-8897}, abstract = {

Curved magnetic filters are often used for the removal of macroparticles from cathodic arc plasmas. This study addresses the need to further reduce losses and improving plasma throughput. The central figure of merit is the system coefficient κ defined as a filtered ion current normalized by the plasma-producing arc current. The coefficient κ is investigated as a function of continuous and pulsed magnetic field operation, magnetic field strength, external electric bias, and arc amplitude. It increases with positive filter bias but saturates at about 15 V for relatively low magnetic field (~10 mT), whereas stronger magnetic fields lead to higher κ with saturation at about 25 V. Further increase of positive bias reduces κ. These findings are true for both pulsed and continuous filters. Bias of pulsed filters has been realized using the voltage drop across a self-bias resistor, eliminating the need for a separate bias circuit. Almost 100 A of filtered copper ions have been obtained in pulsed mode, corresponding to κ ≈ 0.04. The results are interpreted by a simplified potential trough model.

}, author = {Eungsun Byon and Andr{\'e} Anders} } @article {11601, title = {Calculation of Thermodynamic, Electronic, and Optical Properties of Monoclinic Mg2NiH4}, journal = {Journal of Applied Physics}, volume = {91}, number = {8}, year = {2002}, month = {04/2002}, pages = {4879-4885}, chapter = {4879}, abstract = {

Ab initio total-energy density functional theory is used to investigate the low temperature (LT) monoclinic form of Mg2NiH4. The calculated minimum energy geometry of LT\ Mg2NiH4 is close to that determined from neutron diffraction data, and the NiH4 complex is close to a regular tetrahedron. The enthalpies of the phase change to high temperature (HT) pseudo-cubic\ Mg2NiH4 and of hydrogen absorption by Mg2Ni are calculated and compared with experimental values. LT\ Mg2NiH4 is found to be a semiconductor with an indirect band gap of 1.4 eV. The optical dielectric function of LT Mg2NiH4 differs somewhat from that of the HT phase. A calculated thin film transmittance spectrum is consistent with an experimental spectrum.

}, doi = {10.1063/1.1454206}, author = {Whittier R. Myers and Lin-Wang Wang and Thomas J. Richardson and Michael D. Rubin} } @techreport {1159, title = {A Characterization of the Nonresidential Fenestration Market}, year = {2002}, abstract = {

The purpose of this report is to characterize the nonresidential fenestration market in order to better understand market barriers to, and opportunities for, energy-efficient fenestration products. In particular, the goal is to:

The U.S. glass industry is a $27 billion enterprise with both large producers and small firms playing pivotal roles in the industry. While most sectors of the glass industry have restructured and consolidated in the past 20 years, the industry still employs 150,000 workers. Nonresidential glazing accounts for approximately 18\% of overall U.S. glass production. In 1999, nonresidential glazing was supplied to approximately 2.2 billion ft2 of new construction and additions. That same year, nonresidential glazing was also supplied to approximately 1.1 billion ft2 of remodeling construction. With an industry this large and complex, it is to be expected that many market participants can influence fenestration selection. If market barriers to the selection of high performance fenestration products are better understood, then the U. S. Department of Energy (USDOE), the Northwest Energy Efficiency Alliance (NEEA), and others can develop programs and policies that promote greater energy efficiency in commercial glazing products.

}, author = {Arman Shehabi and Charles N. Eley and Dariush K. Arasteh and Phil Degens} } @conference {11825, title = {Energy Efficient Windows in the Southern Residential Windows Market}, booktitle = {2002 ACEEE Summer Study on Energy Efficiency in Buildings}, year = {2002}, month = {08/2002}, address = {Pacific Grove, CA}, abstract = {

The greatest potential in the U.S. for cost-effective energy savings from currently available energy efficient residential windows and skylights exists in the southern market. Prindle and Arasteh recently reported that ten southern states could save over 400 million kwh and 233 MW of peak electricity generating capacity annually by adopting the International Energy Conservation Code (IECC) standard of 0.40 (or less) solar heat gain coefficient (SHGC) for new construction (Prindle \& Arasteh 2001). In 2000, Anello et al. demonstrated savings of 14.7 percent in reduced cooling load with high-performance windows (Anello et al. 2000). In 2002, Wilcox demonstrated savings of 20 percent while simulation analysis estimates cooling energy savings in the 30 percent range (Wilcox 2002).

In the southern market, there is significant opportunity for reducing cooling energy use with low solar gain low-E windows. Yet, the southern market has been slow to embrace this new technology. Market research shows that while low-E products have achieved up to 70 percent of the market share in some colder climates (Jennings, Degens \& Curtis 2002), they have gained less than 10 percent of the southern windows market (Prindle \& Arasteh 2001).

This paper will explore the residential windows market by considering the following: market barriers unique to the southern market; distribution channels in the South; the roles of utilities, codes officials, and other organizations; and other indirect factors that influence this market. This paper will profile current market transformation efforts with case studies of the Florida Windows Initiative, sponsored by the Efficient Windows Collaborative at the Alliance to Save Energy, and the Texas Windows Initiative, sponsored by the American Electric Power Company. Finally, this paper will identify the next steps that will be critical to transforming the southern residential windows market to more efficient window and skylight products.

}, author = {Alison Tribble and Kate Offringa and Bill Prindle and Dariush K. Arasteh and Jay Zarnikau and Arlene Stewart and Ken Nittler} } @techreport {1372, title = {Energy Performance Analysis of Electrochromic Windows in New York Commercial Office Buildings}, year = {2002}, month = {11/2002}, abstract = {

A DOE-2.1E energy simulation analysis of a switchable electrochromic (EC) glazing with daylighting controls has been conducted for prototypical office buildings in New York (NY). The modeling included four types of office buildings: "old" and "new" vintages and large (10,405 m2, 112,000 ft2) and small (502m2, 5400 ft2) buildings. Five commercially available, base case windows with and without interior shades were modeled. Window area varied from 0 to 60\% of the exterior floor-to-floor wall area. The electric lighting had either no controls or continuous daylighting controls. The prototypes were modeled in New York City or Buffalo.

Energy performance ata are given for each of the four perimeter zones. Data are presented as a function of window-to-wall ratio in order to better understand the interactions between 1) electric lighting energy use and daylight admission and 2) solar heat gains and space-conditioning energy use. Maximum and minimum reductions in energy use between the EC glazing and all other base case conditions are also presented. Projected energy use reductions relative to typical specified NY office buildings are presented as an indication of the potential impacts EC glazings might have in retrofit and new construction.

The energy and demand reductions provided by EC glazings with daylighting controls relative to what is typically specified in office buildings in NY are quite substantial. EC glazings will also dampen fluctuations in interior daylight levels and window brightness, potentially increasing visual comfort.

}, author = {Eleanor S. Lee and L. Zhou and Mehry Yazdanian and Vorapat Inkarojrit and Jonathan L. Slack and Michael D. Rubin and Stephen E. Selkowitz} } @techreport {1382, title = {Energy Savings and Pollution Prevention Benefits of Solar Heat Gain Standards in the International Energy Conservation Code}, year = {2002}, abstract = {

The International Energy Conservation Code (IECC), published by the International Code Council, the code development orgalization of building code officials, contains new provisions that save energy and reduce air pollution emissions. Its most significant new provision is a prescriptive standard for solar heat gain control in windows in wanner climate zones. Because solar heat gain through windows is one of the largest components of residential cooling loads, this standard reduces cooling loads dramatically, which in turn reduces electricity consumption, utility bills, and powerplant pollution emissions. It can also reduce the size of cooling equipment, a capital cost saving that can offset increased costs for the higher performance windows needed to meet the standard.

This paper documents the potential energy efficiency, dollar, and pollution reduction benefits of the IECCs solar heat gain standard. Using the RESFEN model developed at Lawrence Berkeley National Laboratory, we simulated a typical new home in ten southern states that would be affected the new IECC solar heat gain standard. Our analysis found that in these ten states, adoption of the IECC in its first year could save 400 million kWh, $38 million in electric bills, and 233 MW of peak electricity generating capacity. The cumulative savings from these homes in year 20 would rise to 80 billion kwh, $7.6 billion in electricity bills, and 4,660 Megawatts of generating capacity. In year twenty, the electric energy savings would also prevent the emission of 20,000 tons of NOx and over 1.5 million tons of carbon equivalent.

Extrapolating the calculations in this paper to include other states with significant cooling load reduction from the IECC leads us to believe peak savings from new construction will total 300MW annually. Given that the window replacement and remodeling market is slightly larger than the new construction market (and here the baseline is poorer performing single glazing), leads to the conclusion that savings which include the remodeling and replacement market should exceed 600MW annually. This would eliminate the need to build two average sized 300MW power plants every year. Additional, similar savings could also be expected from applying this technology to windows in commercial buildings, although we have not accounted for these savings in these estimates.

}, author = {Bill Prindle and Dariush K. Arasteh} } @techreport {1397, title = {An Evaluation of Alternative Qualifying Criteria for Energy Star Windows}, year = {2002}, month = {05/2002}, abstract = {

Energy Star is a voluntaly partnership between the U.S. Department of Energy (DOE), the U.S. Environmental Protection Agency (EPA), and industry. Energy Star, at both DOE andsEPA, is based on legislative mandates to implement voluntary, non-regulatory programs to promote products that are substantially more efficient than required by Federal standards (the DOE Energy Star program originated with Section 127 of the Energy Policy Act of 1992 (EPACT), and the EPA Energy Star program originated with Section 103 of the CleansAir Act amendments of 1990). The base criteria under EPACT requires DOE to establish voluntary energy efficiency product programs that serve to increase the technical energy performance potential of products, are cost-effective for the consumer, save energy and thus reduce green house gas emissions. Criteria used by EPA under the Clean Air Act are similar but reflect a greater emphasis on reducing green house gas emissions.

The primary objective of the partnership is to expand the market for energy-efficient products. EPA and DOE use the Energy Star label to recognize and promlote the most energy-efficient subset of the market. The label is a simple mechanism that allows consumers to easily identify the most energy-efficient products in the marketplace. In developing specifications for the Energy Star label, EPA and DOE consider several key factors, including:

}, author = {Ed Barbour and Dariush K. Arasteh} } @conference {11893, title = {Future Advanced Windows for Zero-Energy Homes}, booktitle = {ASHRAE Transactions}, volume = {109, pt 2}, year = {2002}, month = {06/2003}, pages = {871-888}, address = {Kansas City, MO}, abstract = {

Over the past 15 years, low-emissivity and other technological improvements have significantly improved the energy efficiency of windows sold in the United States. However, as interest increases in the concept of zero-energy homes{\textemdash}buildings that do not consume any nonrenewable or net energy from the utility grid{\textemdash}even today{\textquoteright}s highest-performance window products will not be sufficient. This simulation study compares today{\textquoteright}s typical residential windows, today{\textquoteright}s most efficient residential windows, and several options for advanced window technologies, including products with improved fixed or static properties and products with dynamic solar heat gain properties. Nine representative window products are examined in eight representative U.S. climates. Annual energy and peak demand impacts are investigated. We conclude that a new generation of window products is necessary for zero-energy homes if windows are not to be an energy drain on these homes. Windows with dynamic solar heat gain properties are found to offer significant potential in reducing energy use and peak demands in northern and central climates, while windows with very low (static) solar heat gain properties offer the most potential in southern climates.

}, author = {Joshua S. Apte and Dariush K. Arasteh and Yu Joe Huang} } @techreport {1467, title = {High-Performance Commercial Building Fa{\c c}ades}, year = {2002}, abstract = {

There is a significant and growing interest in the use of highly-glazed fa{\c c}ades in commercial buildings. Large portions of the fa{\c c}ade or even the entire fa{\c c}ade are glazed with relatively high transmittance glazing systems, and typically with some form of sun control as well. With origins in Europe the trend is expanding to other regions, including the United States. A subset of these designs employ a second layer creating a double envelope system, which can then accommodate additional venting and ventilation practices. The stated rationale for use of the these design approaches varies but often includes a connection to occupant benefits as well as sustainable design associated with daylighting and energy savings. As with many architectural trends, understanding the reality of building performance in the field as compared to design intent is often difficult to ascertain. We have been particularly interested in this emerging trend because prior simulation studies have shown that it should be technically possible to produce an all-glass fa{\c c}ade with excellent performance although it is not a simple challenge. The published solutions are varied enough and sufficiently complex that we undertook a year-long international review of advanced fa{\c c}ades to better understand the capabilities and limitations of existing systems and the tools and processes used to create them. This is also intended to create a framework for addressing the missing tools, technologies, processes and data bases that will be needed to turn the promise of advanced fa{\c c}ades into realities. This summary, available as a PDF file and a web site, reports those findings.

}, author = {Eleanor S. Lee and Stephen E. Selkowitz and Christian Kohler and Vladimir Bazjanac and Vorapat Inkarojrit} } @article {11955, title = {In Situ X-Ray Absorption Spectroscopy Study of Hydrogen Absorption by Nickel-Magnesium Thin Films}, journal = {Physical Review B}, volume = {67}, number = {8}, year = {2002}, month = {02/2003}, abstract = {

Structural and electronic properties of co-sputtered Ni-Mg thin films with varying Ni to Mg ratio were studied by in situ x-ray absorption spectroscopy in the Ni L-edge and Mg K-edge regions. Codeposition of the metals led to increased disorder and decreased coordination around Ni and Mg compared to pure metal films. Exposure of the metallic films to hydrogen resulted in formation of hydrides and increased disorder. The presence of hydrogen as a near neighbor around Mg caused a drastic reduction in the intensities of multiple scattering resonances at higher energies. The optical switching behavior and changes in the x-ray spectra varied with Ni to Mg atomic ratio. Pure Mg films with Pd overlayers were converted to MgH2: The H atoms occupy regular sites as in bulk MgH2. Although optical switching was slow in the absence of Ni, the amount of H2 absorption was large. Incorporation of Ni in Mg films led to an increase in the speed of optical switching but decreased maximum transparency. Significant shifts in the Ni L3 and L2 peaks are consistent with strong interaction with hydrogen in the mixed films.

}, doi = {10.1103/PhysRevB.67.085106}, author = {Baker Farangis and Ponnusamy Nachimuthu and Thomas J. Richardson and Jonathan L. Slack and Rupert C.C. Perera and Eric M. Gullikson and Dennis W. Lindle and Michael D. Rubin} } @techreport {58287, title = {Materials, processes, and issues in low-emissivity and solar control coatings}, year = {2002}, month = {12/2002}, abstract = {

Research at DOE and other laboratories can help addressing the durability, performance, and cost issues associated with the energy-saving coatings on glass used in windows of residential and commercial buildings. A brief review is presented on the status of energy-savings coatings, including material systems and processes to manufacture them. Issues such as durability, enhanced performance, dynamic coatings, and multifunctional coatings are considered. Industry and the Department of Energy have overlapping areas of interest, and therefore laboratories should and can have a role in energy-savings research and development of industrial relevance. The report includes specific recent results obtained at Berkeley Lab. It is argued that the properties of ultrathin silver films are determined both by the kinetics of the deposition process and the post-deposition thermodynamics of the material system.

}, author = {Andr{\'e} Anders} } @article {12056, title = {Measured Winter Performance of Storm Windows}, journal = {ASHRAE Transactions}, volume = {109, Part 2}, year = {2002}, month = {07/2003}, address = {Kansas City, MO}, abstract = {

Direct comparison measurements were made between various prime/storm window combinations and a well-weatherstripped, single-hung replacement window with a low-E selective glazing. Measurements were made using an accurate outdoor calorimetric facility with the windows facing north. The double-hung prime window was made intentionally leaky. Nevertheless, heat flows due to air infiltration were found to be small, and performance of the prime/storm combinations was approximately what would be expected from calculations that neglect air infiltration. Prime/low-E storm window combinations performed very similarly to the replacement window. Interestingly, solar heat gain was not negligible, even in north-facing orientation.

}, author = {Joseph H. Klems} } @conference {12099, title = {New Electrochromic Mirror Systems}, booktitle = {Solid State Ionics}, volume = {165}, year = {2002}, month = {08/2002}, pages = {305-308}, address = {Golden, CO}, abstract = {

Variable reflectance coatings (switchable mirrors) have significant advantages over traditional absorbing devices for radiant energy control in a variety of architectural and aerospace applications due to their large dynamic ranges in both transmission and reflection in the visible and near infrared regimes. Although electrochromic and gasochromic metal hydride films have been the primary focus of recent research in this field, other systems merit consideration. Two of these, based on electrochemical conversion of copper to copper oxides and of pnicogens to lithium pnictides are discussed here. Three distinct states are available in the copper system: the highly reflecting metal, the transparent Cu(I) oxide, and the black, highly absorbing Cu(II) oxide. Metallic thin films of elemental antimony and bismuth are reversibly converted to transparent, semiconducting lithium pnictides by cathodic polarization in a non-aqueous lithium electrolyte. Like the metal hydrides, these systems provide substantial modulation of near infrared transmission and reflection, but have somewhat lower visible reflectance in their mirror states.

}, author = {Thomas J. Richardson} } @techreport {1701, title = {Optics Version 5.1.01}, year = {2002}, month = {11/2002}, institution = {Regents of the University of California}, address = {Berkeley, CA}, author = {Richard Versluis and Rebecca Powles and Michael D. Rubin} } @conference {1854, title = {Structural and Electronic Properties of Magnesium-3D Transition Metal Switchable Mirrors}, booktitle = {Fifth International Meeting on Electrochromism}, year = {2002}, month = {12/2002}, address = {Golden, CO}, abstract = {

We have observed reversible mirror-to-transparent state switching in a variety of mixed metal thin films containing magnesium and first-row transition elements including Ni, Fe, Co, Mn, and Ti. The very large changes in both reflectance and transmittance on loading these films with hydrogen are accompanied by significant structural and electronic transformations. The valence states and coordination of metal atoms during hydrogen loading were followed using dynamic in situ transmissionmode X-ray absorption spectroscopy. Time-resolved Mg K-edge and Ni, Co, Mn, and Ti L-edge spectra reflect both reversible and irreversible changes in the metal environments. These spectra are compared to those of reference materials and to predictions from calculations.

}, keywords = {EXAFS, Hydrogen storage materials, NEXAFS, thin films, x-ray diffraction}, doi = {10.1016/j.ssi.2003.08.041}, author = {Baker Farangis and Ponnusamy Nachimuthu and Thomas J. Richardson and Jonathan L. Slack and Bruno K. Meyer and Rupert C.C. Perera and Michael D. Rubin} } @article {1985, title = {X-Ray Absorption Spectroscopy of Transition Metal-Magnesium Hydride Thin Films}, journal = {Journal of Alloys and Compounds}, volume = {356-357}, number = {2003}, year = {2002}, month = {08/2003}, pages = {204-207}, chapter = {204}, abstract = {

Mixed metal thin films containing magnesium and a first-row transition element exhibit very large changes in both reflectance and transmittance on exposure to hydrogen gas. Changes in electronic structure and coordination of the magnesium and transition metal atoms during hydrogen absorption were studied using dynamic in situ transmission mode X-ray absorption spectroscopy. Mg K-edge and Ni, Co, and Ti L-edge spectra reflect both reversible and irreversible changes in the metal environments. A significant shift in the nickel L absorption edge shows it to be an active participant in hydride formation. The effect on cobalt and titanium is much less dramatic, suggesting that these metals act primarily as catalysts for formation of magnesium hydride.

}, keywords = {EXAFS, Hydrogen storage materials, NEXAFS, thin films, x-ray diffraction}, doi = {10.1016/S0925-8388(02)01237-9}, author = {Thomas J. Richardson and Baker Farangis and Jonathan L. Slack and Ponnusamy Nachimuthu and Rupert C.C. Perera and Nobumichi Tamura and Michael D. Rubin} } @book {11676, title = {Daylight in Buildings. A Source Book on Daylighting Systems and Components}, year = {2001}, note = {

Download: Daylight in Buildings
A hard copy of the book may be obtained by sending a request to Ellen Thomas at\ EllenThomas@lbl.gov.\ Only one copy per individual, U.S. or Canadians only.\  If you reside elsewhere, go to\ http://task21.iea-shc.org/to find out how to obtain a copy in your country.\ 

}, url = {https://facades.lbl.gov/daylight-buildings-source-book-daylighting-systems}, author = {Nancy Ruck and {\O}yvind Aschehoug and Sirri Aydinli and Jens Christoffersen and Gilles Courret and Ian Edmonds and Roman Jakobiak and Martin Kischkoweit-Lopin and Martin Klinger and Eleanor S. Lee and Laurent Michel and Jean-Louis Scartezzini and Stephen E. Selkowitz} } @conference {11950, title = {Improving Information Technology to Maximize Fenestration Energy Efficiency}, booktitle = {Performance of Exterior Envelopes of Whole Buildings VIII}, year = {2001}, month = {12/2001}, address = {Clearwater Beach, FL}, abstract = {

Annual heating and cooling energy loads through fenestration products in both residential and commercial buildings are a significant fraction of national energy requirements. In the residential sector, 1.34 and 0.37 quads are required for heating and cooling respectively (DOE Core Data Book, 2000). In commercial buildings, cooling energy use to compensate for fenestration product solar heat gain is estimated at 0.39 quads; heating energy use to compensate for heat loss through fenestration products is estimated at 0.19 quads. Advanced products offer the potential to reduce these energy uses by at least 50\% (Frost et. al. 1993). Potential electric lighting savings from fenestration products are estimated at 0.4 quads if daylight can be used effectively so that electric lighting in commercial building perimeter zones can be reduced.

Software has begun to make an impact on the design and deployment of efficient fenestration products by making fenestration product performance ratings widely available. These ratings, which are determined in part using software programs such as WINDOW/THERM/Optics, VISION/FRAME, and WIS, can now easily be used by architects, engineers, professional fenestration product specifiers, and consumers. Information on the properties of fenestration products has also influenced state and national codes (IECC, ASHRAE 90.1) and aided voluntary market transformation programs, such as the Efficient Windows Collaborative and the Energy Star Windows program, which promote efficient fenestration products.

}, author = {Dariush K. Arasteh and Robin Mitchell and Christian Kohler and Charlie Huizenga and Dragan C. Curcija} } @conference {11970, title = {Infrared Thermography Measurements of Window Thermal Test Specimen: Surface Temperatures}, booktitle = {ASHRAE Seminar}, year = {2001}, month = {01/2002}, address = {Atlantic City, NJ}, abstract = {

Temperature distribution data are presented for the warm-side surface of three different window specimens. The specimens were placed between warm and cold environmental chambers that were operated in steady state at two different standard design conditions for winter heating. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) temperature conditions were 21.1 deg. C (70 deg. F) and -17.8 deg. C (0 deg. F) on the warm and cold sides, respectively. The International Standards Organization (ISO) temperature conditions were 20.0 deg. C (68.0 deg. F) and 0.0 deg. C (32.0 deg. F) on the warm and cold sides, respectively. Surface temperature maps were compiled using an infrared thermographic system with an external referencing technique, a traversing point infrared thermometer and thermocouples. The infrared techniques allow detailed, non-intrusive mapping of surface temperatures. Surface temperature data are plotted for the vertical distribution along the centerline of the window specimen. This paper is part of larger round-robin collaborative effort that studied this same set of window specimens. These studies were conducted to improve and check the accuracy of computer simulations for predicting the condensation resistance of window products. Data collected for a Calibrated Transfer Standard showed that convective effects outside the window gap are important for predicting surface temperatures.

}, author = {Brent T. Griffith and Howdy Goudey and Dariush K. Arasteh} } @techreport {1527, title = {The Integrated Energy-Efficiency Window-Wall System}, year = {2001}, author = {Michael Arney and James Fairman and John Carmody and Dariush K. Arasteh} } @conference {11988, title = {Integrating Advanced Fa{\c c}ades into High Performance Buildings}, booktitle = {Glass Processing Days: 7th International Conference on Architectural and Automotive Glass}, year = {2001}, month = {06/2001}, address = {Tampere, Finland}, abstract = {

Glass is a remarkable material but its functionality is significantly enhanced when it is processed or altered to provide added intrinsic capabilities. The overall performance of glass elements in a building can be further enhanced when they are designed to be part of a complete fa{\c c}ade system. Finally the fa{\c c}ade system delivers the greatest performance to the building owner and occupants when it becomes an essential element of a fully integrated building design. This presentation examines the growing interest in incorporating advanced glazing elements into more comprehensive fa{\c c}ade and building systems in a manner that increases comfort, productivity and amenity for occupants, reduces operating costs for building owners, and contributes to improving the health of the planet by reducing overall energy use and environmental impacts. We explore the role of glazing systems in dynamic and responsive fa{\c c}ades that provide the following functionality:

Enhanced sun protection and cooling load control while improving thermal comfort and providing most of the light needed with daylighting;

Enhanced air quality and reduced cooling loads using natural ventilation schemes employing the fa{\c c}ade as an active air control element;

Reduced operating costs by minimizing lighting, cooling and heating energy use by optimizing the daylighting- thermal tradeoffs;

Net positive contributions to the energy balance of the building using integrated photovoltaic systems;

Improved indoor environments leading to enhanced occupant health, comfort and performance.

In addressing these issues fa{\c c}ade system solutions must of course respect the constraints of latitude, location, solar orientation, acoustics, earthquake and fire safety, etc. Since climate and occupant needs are dynamic variables, in a high performance building the fa{\c c}ade solution must have the capacity to respond and adapt to these variable exterior conditions and to changing occupant needs. This responsive performance capability can also offer solutions to building owners where reliable access to the electric grid is a challenge, in both less-developed countries and in industrialized countries where electric generating capacity has not kept pace with growth. We find that when properly designed and executed as part of a complete building solution, advanced fa{\c c}ades can provide solutions to many of these challenges in building design today.

}, author = {Stephen E. Selkowitz} } @article {12068, title = {A Method for Simulating the Performance of Photosensor-Based Lighting Controls}, journal = {Energy and Buildings}, volume = {34}, number = {9}, year = {2001}, pages = {883-889}, abstract = {

The unreliability of photosensor-based lighting controls continues to be a significant market barrier that prevents widespread acceptance of daylight dimming controls in commercial buildings. Energy savings from the use of daylighting in commercial buildings is best realized through the installation of reliable photoelectric lighting controls that dim electric lights when sufficient daylight is available to provide adequate background and/or task illumination. In prior work, the authors discussed the limitations of current simulation approaches and presented a robust method to simulate the performance of photosensor-based controls using an enhanced version of the radiance lighting simulation package. The method is based on the concept of multiplying two fisheye images: one generated from the angular sensitivity of the photosensor and the other from a 180 or 360 deg. fisheye image of the space as seen by the photosensor. This paper includes a description of the method, its validation and possible applications for designing, placing, calibrating and commissioning photosensor-based lighting controls.

}, author = {Charles K. Ehrlich and Konstantinos M. Papamichael and Judy Lai and Kenneth L. Revzan} } @article {12075, title = {Mixed Metal Films with Switchable Optical Properties}, journal = {Applied Physics Letters}, volume = {80}, number = {8}, year = {2001}, month = {02/2002}, pages = {1349-1351}, abstract = {

Thin, Pd-capped metallic films containing magnesium and first row transition metals (Mn, Fe, Co) switch reversibly from their initial reflecting state to visually transparent states when exposed to gaseous hydrogen or following reduction cathodic polarization in an alkaline electrolyte. Reversion to the reflecting state is achieved by exposure to air or by anodic polarization. The films were prepared by co-sputtering from one magnesium target and one manganese, iron, or cobalt target. Both the dynamic optical switching range and the speed of the transition depend on the magnesium-transition metal ratio. Infrared spectra of films in the transparent, hydrided (deuterided) states support the presence of the intermetallic hydride phases Mg3MnH7, Mg2FeH6, and Mg2CoH5.

}, doi = {10.1063/1.1454218}, author = {Thomas J. Richardson and Jonathan L. Slack and Baker Farangis and Michael D. Rubin} } @conference {1803, title = {Simulating the Operation of Photosensor-Based Lighting Controls}, booktitle = {2001 Building Simulation 7th International Building Performance Simulation Association Conference}, year = {2001}, month = {08/2001}, address = {Rio de Janeiro, Brazil}, abstract = {

Energy savings from the use of daylighting in commercial buildings are realized through implementation of photoelectric lighting controls that dim electric lights when sufficient daylight is available to provide adequate workplane illumination. The dimming level of electric lighting is based on the signal of a photosensor. Current simulation approaches for such systems are based on the questionable assumption that the signal of the photosensor is proportional to the task illuminance. This paper presents a method that simulates the performance of photosensor controls considering the acceptance angle, angular sensitivity, placement of the photosensor within a space, and color correction filter. The method is based on the multiplication of two fisheye images: one generated from the angular sensitivity of the photosensor and the other from a 180- or 360-degree fisheye image of the space as seen by the photosensor. The paper includes a detailed description of the method and its implementation, example applications, and validation results based on comparison with measurements in an actual office space.

}, author = {Charles K. Ehrlich and Konstantinos M. Papamichael and Judy Lai and Kenneth L. Revzan} } @conference {1820, title = {Solar Heat Gain through a Skylight in a Light Well}, booktitle = {ASHRAE Chicago}, volume = {108, Part 1}, year = {2001}, month = {01/2003}, pages = {512-524}, address = {Chicago, IL}, abstract = {

Detailed heat flow measurements on a skylight mounted on a light well of significant depth are presented. It is shown that during the day much of the solar energy that strikes the walls of the well does not reach the space below. Instead, this energy is trapped in the stratified air of the light well and eventually either conducted through the walls of the well or back out through the skylight. The standard model for predicting fenestration heat transfer does not agree with the measurements when it is applied to the skylight/well combination as a whole (the usual practice), but does agree reasonably well when it is applied to the skylight alone, using the well air temperature near the skylight. A more detailed model gives good agreement. Design implications and future research directions are discussed.

}, author = {Joseph H. Klems} } @article {1875, title = {Switchable Mirrors Based on Nickel-Magnesium Films}, journal = {Applied Physics Letters}, volume = {78}, number = {20}, year = {2001}, month = {05/2001}, pages = {3047-3049}, chapter = {3047}, abstract = {

An electrochromic mirror electrode based on reversible uptake of hydrogen in nickel magnesium alloy films is reported. Thin, magnesium-rich Ni-Mg films prepared on glass substrates by cosputtering from Ni and Mg targets are mirror-like in appearance and have low visible transmittance. Upon exposure to hydrogen gas or on cathodic polarization in alkaline electrolyte, the films take up hydrogen and become transparent. When hydrogen is removed, the mirror properties are recovered. The transition is believed to result from reversible formation of Mg2NiH4 and MgH2. A thin overlayer of palladium was found to enhance the kinetics of hydrogen insertion and extraction, and to protect the metal surface against oxidation.

}, doi = {10.1063/1.1371959 }, author = {Thomas J. Richardson and Jonathan L. Slack and Robert D. Armitage and Robert Kostecki and Baker Farangis and Michael D. Rubin} } @techreport {1893, title = {THERM 5.0 User{\textquoteright}s Manual}, year = {2001}, author = {Windows and Daylighting Group} } @article {1895, title = {THERM Simulations of Window Indoor Surface Temperatures for Predicting Condensation}, journal = {ASHRAE Transactions}, volume = {109, Part 1}, year = {2001}, month = {01/ 2002}, pages = {593-599}, address = {Atlantic City, NJ}, abstract = {

As part of a round robin project, the performance of two wood windows and a Calibrated Transfer Standard was modeled using the THERM heat-transfer simulation program. The resulting interior surface temperatures can be used as input to condensation resistance rating procedures. The Radiation and Condensation Index features within THERM were used to refine the accuracy of simulation results. Differences in surface temperatures between the Basic calculations and those incorporating the Radiation and/or Condensation Index features are demonstrated and explained.

}, author = {Christian Kohler and Dariush K. Arasteh and Robin Mitchell} } @techreport {1971, title = {WINDOW 5.0 User Manual for Analyzing Window Thermal Performance}, year = {2001}, author = {Robin Mitchell and Christian Kohler and Dariush K. Arasteh and Charlie Huizenga and Dragan C. Curcija} } @article {11506, title = {21st Century Windows: Electrochromic Windows and Other Glazing Technologies}, journal = {Fenestration Magazine}, number = {Sep-00}, year = {2000}, abstract = {

One of our challenges for the 21st century will be to try to reduce adverse societal impacts on our planet. Buildings account for one of the nations largest energy costs and are the biggest source of greenhouse gas emissions. Within the building sector, windows were historically viewed as one of the weak links in buildings. The early response to this perspective was legislation to restrict window usage. The big conceptual leap in the last 25 years has been the recognition that better window technology and better building design can not only reduce these negative impacts, but can convert them into tangible human and economic benefits. The window industry has risen to the challenge of producing the cost-effective products that help translate researchers predictions into market reality. A look at trends in glazing and new findings from an electrochromic window study by the Lawrence Berkeley National Laboratory (LBNL) provides some additional clues on where fenestration technology will take us in the 21st Century.

Two notable achievements have marked progress for the window industry in the last 25 years: Low-E coatings and spectrally selective cool glazings.

}, author = {Stephen E. Selkowitz} } @conference {11791, title = {Electrochromic Windows for Commercial Buildings: Monitored Results from a Full-Scale Testbed}, booktitle = {ACEEE 2000 Summer Study on Energy Efficiency in Buildings, Efficiency and Sustainability, August 20-25, 2000}, year = {2000}, month = {04/2000}, address = {Pacific Grove, CA}, abstract = {

Electrochromic glazings promise to be the next major advance in energy-efficient window technology, helping to transform windows and skylights from an energy liability to an energy source for the nations building stock. Monitored results from a full-scale demonstration of large-area electrochromic windows are given. The test consisted of two side-by-side, 3.7x4.6 m, office-like rooms. In each room, five 62x173-cm lower electrochromic windows and five 62x43-cm upper electrochromic windows formed a large window wall. The window-to-exterior wall ratio (WWR) was 0.40. The southeast-facing electrochromic windows had an overall visible transmittance (Tv) range of Tv =0.11-0.38 and were integrated with a dimmable electric lighting system to provide constant work plane illuminance and to control direct sun.

Daily lighting use from the automated electrochromic window system decreased by 6 to 24\% compared to energy use with static, low-transmission (Tv =0.11), unshaded windows in overcast to clear sky winter conditions in Oakland, California. Daily lighting energy use increased as much as 13\% compared to lighting energy use with static windows that had Tv =0.38. Even when lighting energy savings were not obtainable, the visual environment produced by the electrochromic windows, indicated by well-controlled window and room luminance levels, was significantly improved for computer-type tasks throughout the day compared to the visual environment with unshaded 38\%-glazing. Cooling loads were not measured, but previous building energy simulations indicate that additional savings could be achieved. To ensure visual and thermal comfort, electrochromics require occasional use of interior or exterior shading systems when direct sun is present. Other recommendations to improve electrochromic materials and controls are noted along with some architectural constraints.

}, author = {Eleanor S. Lee and Dennis L. DiBartolomeo and Stephen E. Selkowitz} } @conference {11799, title = {Electrochromism in Copper Oxide Thin Films}, booktitle = {4th International Meeting on Electrochromism}, year = {2000}, month = {08/2000}, address = {Uppsala, Sweden}, abstract = {

Transparent thin films of copper(I) oxide prepared on conductive SnO2:F glass substrates by anodic oxidation of sputtered copper films or by direct electrodeposition of Cu2O transformed reversibly to opaque metallic copper films when reduced in alkaline electrolyte. In addition, the same Cu2O films transform reversibly to black copper(II) oxide when cycled at more anodic potentials. Copper oxide-to-copper switching covered a large dynamic range, from 85\% and 10\% photopic transmittance, with a coloration efficiency of about 32 cm2/C. Gradual deterioration of the switching range occurred over 20 to 100 cycles. This is tentatively ascribed to coarsening of the film and contact degradation caused by the 65\% volume change on conversion of Cu to Cu2O. Switching between the two copper oxides (which have similar volumes) was more stable and more efficient (CE = 60 cm2/C), but covered a smaller transmittance range (60\% to 44\% T). Due to their large electrochemical storage capacity and tolerance for alkaline electrolytes, these cathodically coloring films may be useful as counter electrodes for anodically coloring electrode films such as nickel oxide or metal hydrides.

}, author = {Thomas J. Richardson and Jonathan L. Slack and Michael D. Rubin} } @conference {12032, title = {Liquid Phase Deposition of Electrochromic Thin Films}, booktitle = {Electrochimica Acta}, volume = {46}, year = {2000}, month = {08/2000}, pages = {2119-2123}, address = {Uppsala, Sweden}, abstract = {

Thin films of titanium, zirconium and nickel oxides were deposited on conductive SnO2:F glass substrates by immersion in aqueous solutions. The films are transparent, conformal, of uniform thickness and appearance, and adhere strongly to the substrates. On electrochemical cycling, TiO2, mixed TiO2-ZrO2, and NiOx films exhibited stable electrochromism with high coloration efficiencies. These nickel oxide films were particularly stable compared with films prepared by other non-vacuum techniques. The method is simple, inexpensive, energy efficient, and readily scalable to larger substrates.

}, author = {Thomas J. Richardson and Michael D. Rubin} } @article {12093, title = {Natural Convection Effects in Three-Dimensional Window Frames with Internal Cavities}, journal = {ASHRAE Transactions}, volume = {107, Part 2}, year = {2000}, month = {06/2001}, address = {Cincinnati, Ohio}, abstract = {

This paper studies three-dimensional natural convection effects in window frames with internal cavities. Infrared (IR) thermography experiments, computational fluid dynamics (CFD) simulations, and calculations with traditional software for simulating two-dimensional heat conduction were conducted. The IR thermography experiments mapped surface temperatures during steady-state thermal tests between ambi-ent thermal chambers set at 0 deg. C and 20 deg. C. Using anon-contact infrared scanning radiometer and an external referencing technique, we were able to obtain surface temperature maps with a resolution of 0.1 deg. C and 3 mm and an estimated uncertainty of 0.5 deg. C and +/-3 mm. The conjugate CFD simulations modeled the enclosed air cavities, frame section walls, and foam board surround panel. With the two-dimensional heat conduction simulation software, weusedcorrelations to model heat transfer in the air cavities. For both the CFD simulations and the conduction simulation software, boundary conditions at the external air/solid interface were modeled using constant surface heat-transfer coefficients with fixed ambient air temperatures.

Different cases were studied, including simple, four-sided frame sections (with one open internal cavity), simple vertical sections with a single internal cavity, and horizontal sections with a single internal cavity. The sections tested in the Infrared Thermography Laboratory (IR lab) were made of PVC. Both PVC and thermally broken aluminum sections were modeled. Based on the current investigations, it appears that the thermal transmittance or U-factor of a four-sided section can be found by calculating the average of the thermal transmittance of the respective single horizontal and vertical sections. In addition, we conclude that two-dimensional heat transfer simulation software agrees well with CFD simulations if the natural convection correlations used for the internal cavities are correct.

}, author = {Arlid Gustavsen and Brent T. Griffith and Dariush K. Arasteh} } @conference {12153, title = {Optical Properties of Glazing Materials at Normal Incidence}, booktitle = {Revista della Statzione Sperimentale del Vetro}, year = {2000}, month = {10/2000}, pages = {13-16}, address = {Paris, France}, abstract = {

Measurements of spectral transmittance T and reflectance R at normal incidence continue to be the most common and accurate source of energy performance data for glazing materials. Prediction of these radiometric properties from more fundamental materials data is often confounded by the complexity and uncertainty of coating structures. Angle-dependent radiometric properties of coated glazing will probably be predicted from normal-incidence data rather than being measured at many angles. The general error level demonstrated in round-robin tests is on the order 1-2\%; it is often necessary to achieve better levels of performance. Based on results obtained following the round-robin tests, it is expected that accuracy of better than 0.5\% can be generally achieved. A new type of absolute standard reference is described and tested with promising results.

}, author = {Michael D. Rubin and Rebecca Powles} } @techreport {1822, title = {Solar Heat Gain Through Fenestrations Containing Shading: Procedures for Estimating Performace from Minimal Data}, year = {2000}, abstract = {

The computational methods for calculating the properties of glazing systems containing shading from the properties of their components have been developed, but the measurement standards and property data bases necessary to apply them have not. It is shown that with a drastic simplifying assumption these methods can be used to calculate system solar-optical properties and solar heat gain coefficients for arbitrary glazing systems, while requiring limited data about the shading. Detailed formulas are presented, and performance multipliers are defined for the approximate treatment of simple glazings with shading. As higher accuracy is demanded, the formulas become very complicated.

}, author = {Joseph H. Klems} } @techreport {1892, title = {THERM 2.1 NFRC Simulation Manual}, year = {2000}, month = {07/2000}, pages = {260}, abstract = {

This document, the THERM 2.1 NFRC Simulation Manual, discusses how to use THERM to model products for NFRC certified simulations and assumes that the user is already familiar with the THERM program. In order to learn how to use THERM, it is necessary to become familiar with the material in the THERM User{\textquoteright}s Manual.

In general, this manual references the THERM User{\textquoteright}s Manual rather than repeating the information.

If there is a conflict between the THERM User{\textquoteright}s Manual and the THERM 2.1 NFRC Simulation Manual, the THERM 2.1 NFRC Simulation Manual takes precedence.

}, author = {Robin Mitchell and Christian Kohler and Dariush K. Arasteh and Elizabeth U. Finlayson and Charlie Huizenga and Dragan C. Curcija and John Carmody} } @article {1911, title = {Three-Dimensional Conjugate Computational Fluid Dynamics Simulations of Internal Window Frame Cavities Validated Using IR Thermography}, journal = {ASHRAE Transactions}, volume = {107}, year = {2000}, month = {06/2001}, pages = {538-549}, address = {Cincinnati, Ohio}, abstract = {

This paper studies the effectiveness of one commercial computational fluid dynamics (CFD) program for simulating combined natural convection and heat transfer in three dimensions for air-filled cavities similar to those found in the extruded frame sections of windows. The accuracy of the conjugate CFD simulations is evaluated by comparing results for surface temperature on the warm side of the specimens to results from experiments that use infrared (IR) thermography to map surface temperatures during steady-state thermal tests between ambient thermal chambers set at 0 {\textdegree}C and 20 {\textdegree}C. Validations using surface temperatures have been used in previous studies of two-dimensional simulations of glazing cavities with generally good results. Using the techniques presented and a noncontact infrared scanning radiometer we obtained surface temperature maps with a resolution of 0.1 {\textdegree}C and 3 mm and an estimated uncertainty of +/-0.5 {\textdegree}C and +/-3mm. Simulation results are compared to temperature line and contour plots for the warm side of the specimen. Six different cases were studied, including a simple square section in a single vertical cavity and two four-sided frame cavities as well as more complex H- and U-shaped sections. The conjugate CFD simulations modeled the enclosed air cavities, the frame section walls, and the foam board surround panel. Boundary conditions at the indoor and outdoor air/solid interface were modeled using constant surface heat-transfer coefficients with fixed ambient-air temperatures. In general, there was good agreement between the simulations and experiments, although the accuracy of the simulations is not explicitly quantified. We conclude that such simulations are useful for future evaluations of natural convection heat transfer in frame cavities.

}, author = {Arlid Gustavsen and Brent T. Griffith and Dariush K. Arasteh} } @conference {1937, title = {U-Values of Flat and Domed Skylights}, booktitle = {2000 ASHRAE Annual Meeting}, volume = {106, Part 2}, year = {2000}, month = {06/2000}, address = {Minneapolis, Minnesota}, abstract = {

Data from nighttime measurements of the net heat flow through several types of skylights is presented. A well-known thermal test facility was reconfigured to measure the net heat flow through the bottom of a skylight/light well combination. Use of this data to determine the U-factor of the skylight is considerably more complicated than the analogous problem of a vertical fenestration contained in a test mask. Correction of the data for heat flow through the skylight well surfaces and evidence for the nature of the heat transfer between the skylight and the bottom of the well is discussed. The resulting measured U-values are presented and compared with calculations using the WINDOW4 and THERM programs.

}, author = {Joseph H. Klems} } @conference {11671, title = {A Database of Window Annual Energy Use in Typical North American Residences}, booktitle = {2000 ASHRAE Winter Meeting}, year = {1999}, month = {02/2000}, address = {Dallas, Texas}, abstract = {

This paper documents efforts by the National Fenestration Rating Council to develop a database on annual energy impacts of windows in a typical new, single family, single story residence in various U.S. and Canadian climates. The result is a database of space heating and space cooling energies for 14 typical windows in 52 North American climates. (Future efforts will address the effects of skylights.) This paper describes how this database was created, documents the assumptions used in creating this database, elaborates on assumptions, which need further research, examines the results, and describes the possible uses of the database.

}, author = {Dariush K. Arasteh and Yu Joe Huang and Robin Mitchell and Robert D. Clear and Christian Kohler} } @techreport {1235, title = {Daylighting Simulation: Methods, Algorithms, and Resources}, year = {1999}, abstract = {

The search for and collection of daylighting analysis methods and algorithms led to two important observations. First, there is a wide range of needs for different types of methods to produce a complete analysis tool. These include:

Second, very advantageously, there have been rapid advances in many basic methods in these areas, due to other forces. They are in part driven by:

This has led to a very rich set of information resources that have direct applicability to the small daylighting analysis community. Furthermore, much of this information is in fact available online.

}, author = {William L. Carroll} } @conference {11844, title = {Establishing the Value of Advanced Glazings}, booktitle = {Glass in Buildings: An International Conference on the Use of Glass as an Architectural/Engineering Form and Material}, year = {1999}, month = {04/1999}, address = {Bath, UK}, abstract = {

Numerous glazing technologies are under development worldwide to improve the performance of building facades. High-performance glazings can provide substantial energy and related environmental benefits, but often at greatly increased first cost when compared to conventional design solutions. To increase market viability, we discuss strategies to reduce the actual and owner-perceived costs associated with developing and producing advanced window systems, specifically switchable electrochromic glazings, and we also suggest marketing strategies designed to appeal to early adopter and mainstream purchasers. These strategies may be applicable to a broad range of advanced glazing materials.

}, author = {Eleanor S. Lee and Stephen E. Selkowitz} } @article {11859, title = {Evaluation of the Plasma Distribution of a Quasi-Linear Constricted Plasma Source}, journal = {IEEE Transactions on Plasma Science}, volume = {27}, number = {1}, year = {1999}, month = {02/1999}, pages = {82-83}, chapter = {82}, abstract = {

The quasi-linear constricted plasma source is a downstream plasma source with ten linearly aligned discharge cells. Each cell operates on the basis of a constricted glow discharge. The plasma output can easily be monitored by the plasma-emitted light. The information is not only intuitive but can also be used to operate on-line feedback control of the plasma source which is important for large-area plasma processing of materials.

}, keywords = {Constricted plasma source, gas plasma flow, plasma diagnostics, plasma processing of materials}, author = {Andr{\'e} Anders and Robert A. MacGill and Michael D. Rubin} } @conference {11913, title = {High Performance Glazing Systems: Architectural Opportunities for the 21st Century}, booktitle = {Glass Processing Days 99 Conference}, year = {1999}, month = {06/1999}, address = {Tampere, Finland}, abstract = {

Glazing systems will fulfill important new roles in buildings in the 21st century. This paper provides an overview of three different functional impacts for advanced glazing systems. New technology and better integration with daylighting and climate control systems allow advanced glazings in building facades to 1) improve the comfort and performance of building occupants, 2) add value and reduce energy operating costs for building owners, and 3) assist in national and global efforts to reduce greenhouse gas emissions that contribute to global warming.

}, author = {Stephen E. Selkowitz} } @article {12094, title = {Net Energy Performance Measurements on Electrochromic Skylights}, journal = {Energy and Buildings}, volume = {33}, number = {2}, year = {1999}, pages = {93-102}, abstract = {

Tests of skylights made from prototype electrochromic glazings were performed in a room-sized calorimetric test facility under ambient outdoor summer conditions in Reno, NV. The test methodology and the resultant measurements of skylight heat flows and temperatures with their diurnal variations are presented. Special test issues relating to the dynamic switchable nature of the glazings are discussed.

}, author = {Joseph H. Klems} } @article {12213, title = {Refractive Index Changes of Pd-Coated Magnesium Ianthanide Switchable Mirrors Upon Hydrogen Insertion}, journal = {Journal of Applied Physics}, volume = {85}, number = {1}, year = {1999}, month = {01/1999}, pages = {408-413}, chapter = {408}, abstract = {

The optical effect upon insertion of hydrogen into Pd-coated magnesium lanthanide switchable mirrors is investigated in terms of the changes of their complex refractive indices. A significant change in the optical constants of LnMg layers is seen between the as-deposited state and the dehydrided state after one cycle. Furthermore, the optical effect of switching the Pd cap layer to a PdH cap layer was determined. It is shown that the Pd layer mainly limits the visible transmittance of the hydrided stack to about 35\%-40\%. Whereas the extinction coefficient of dehydrided LnMg layers at 550 nm is between 2.2 and 3.1, it is as low 10-4 as in the transparent state. This is of great promise to applications requiring large optical contrast (e.g., optical switches).

}, issn = {0021-8979 }, doi = {10.1063/1.369399}, author = {Klaus von Rottkay and Michael D. Rubin and Peter A. Duine} } @techreport {1770, title = {RESFEN 3.1: A PC Program for Calculating the Heating and Cooling Energy Use of Windows in Residential Buildings}, year = {1999}, month = {08/1999}, institution = {Lawrence Berkeley National Laboratory}, address = {Berkeley}, abstract = {

A computer tool such as RESFEN can help consumers and builders pick the most energy-efficient and cost-effective window for a given application, whether it is a new home, an addition, or a window replacement. It calculates heating and cooling energy use and associated costs as well as peak heating and cooling demand for specific window products. Users define a specific scenario by specifying house type (single-story or two-story), geographic location, orientation, electricity and gas cost, and building configuration details (such as wall, floor, and HVAC system type). Users also specify size, shading, and thermal properties of the window they wish to investigate. The thermal properties that RESFEN requires are: U-factor, Solar Heat Gain Coefficient, and air leakage rate. RESFEN calculates the energy and cost implications of the window compared to an insulated wall. The relative energy and cost impacts of two different windows can be compared.

RESFEN 3.0 was a major improvement over previous versions because it performs hourly calculations using a version of the DOE 2.1E (LBL 1980, Winkelmann et al. 1993) energy analysis simulation program. RESFEN 3.1 incorporates additional improvements including input assumptions for the base case buildings taken from the National Fenestration Rating Council (NFRC) Annual Energy Subcommittee{\textquoteright}s efforts.

}, author = {Robin Mitchell and Yu Joe Huang and Dariush K. Arasteh and Robert Sullivan and Santosh Phillip} } @conference {12227, title = {Residential Fenestration Performance Analysis Using RESFEN 3.1}, booktitle = {Thermal Performance of the Exterior Envelopes of Buildings VII}, year = {1999}, month = {12/1998}, address = {Clearwater Beach, FL}, abstract = {

This paper describes the development efforts of RESFEN 3.1, a PC-based computer program for calculating the heating and cooling energy performance and cost of residential fenestration systems. The development of RESFEN has been coordinated with ongoing efforts by the National Fenestration Rating Council (NFRC) to develop an energy rating system for windows and skylights to maintain maximum consistency between RESFEN and NFRCs planned energy rating system. Unlike previous versions of RESFEN, that used regression equations to replicate a large data base of computer simulations, Version 3.1 produces results based on actual hour-by-hour simulations. This approach has been facilitated by the exponential increase in the speed of personal computers in recent years. RESFEN 3.1 has the capability of analyzing the energy performance of windows in new residential buildings in 52 North American locations. The user describes the physical, thermal and optical properties of the windows in each orientation, solar heat gain reductions due to obstructions, overhangs, or shades, and the location of the house. The RESFEN program then models a prototypical house for that location and calculates the energy use of the house using the DOE-2 program. The user can vary the HVAC system, foundation type, and utility costs. Results are presented for the annual heating and cooling energy use, energy cost, and peak energy demand of the house, and the incremental energy use or peak demand attributable to the windows in each orientation. This paper describes the capabilities of RESFEN 3.1, its usefulness in analyzing the energy performance of residential windows and its development effort and gives insight into the structure of the computer program. It also discusses the rationale and benefits of the approach taken in RESFEN in combining a simple-to-use graphical front-end with a detailed hour-by-hour simulation engine to produce an energy analysis tool for the general public that is user-friendly yet highly accurate.

}, author = {Yu Joe Huang and Robin Mitchell and Dariush K. Arasteh and Stephen E. Selkowitz} } @article {1828, title = {Solid State Gadolinium-Magnesium Hydride Optical Switch}, journal = {Applied Physics Letters}, volume = {75}, number = {13}, year = {1999}, month = {09/1999}, pages = {1863-1865}, chapter = {1863}, abstract = {

The optical switching properties of gadolinium-magnesium hydride have been demonstrated in a solid-state electrochromic device. With positive polarization of the hydride electrode, the visible reflectance approaches 35\% with virtually zero transmission, while with negative polarization, the visible transmission exceeds 25\% at 650 nm. The switching is reversible, with intermediate optical properties between the transparent and reflecting states.

}, url = {http://dx.doi.org/10.1063/1.124853}, author = {Robert D. Armitage and Michael D. Rubin and Thomas J. Richardson and Nada O{\textquoteright}Brien and Yong Chen} } @conference {1890, title = {THERM 2.0: A Building Component Model for Steady-State Two-Dimensional Heat Transfer}, booktitle = {Building Simulation 99, International Building Performance Simulation Association (IBPSA)}, year = {1999}, month = {09/1999}, address = {Kyoto, Japan}, abstract = {

THERM 2.0 is a state-of-the-art software program, available without cost, that uses the finite-element method to model steady-state, two-dimensional heat-transfer problems. It includes a powerful simulation engine combined with a simple, interactive interface and graphic results. Although it was developed primarily to model thermal properties of windows, it is appropriate for other building components such as walls, doors, roofs, and foundations, and is useful for modeling thermal bridges in many other contexts, such as the design of equipment.

}, author = {Charlie Huizenga and Dariush K. Arasteh and Elizabeth U. Finlayson and Robin Mitchell and Brent T. Griffith and Dragan C. Curcija} } @techreport {1916, title = {Toward a Virtual Building Laboratory}, year = {1999}, month = {03/1999}, abstract = {

Buildings account for about one-third of all energy used in the US and about two-thirds of all electricity, with associated environmental impacts.(EIA 1996) After more than 20 years of DOE-supported research universities and national laboratories, a great deal is known about the energy performance of buildings and especially their components and subsystems. The development and market introduction of improved energy efficient technology, such as low-E windows and electronic ballasts, have helped reduce energy use, and the resultant savings will increase, as use of the new technologies becomes more widespread. A variety of approaches to speed market penetration have been and are being pursued, including information dissemination, research to evaluate performance and development of computer tools for making energy performance simulations available to architects and engineers at the earliest design stages. Public-domain computer building energy simulation models, (BLAST_Support_Office 1992; Winkelmann, Birdsall et al. 1993) a controversial idea 20 years ago, have been extremely successful in facilitating the design of more energy-efficient buildings and providing the technical basis for improved state building codes, federal guidelines, and voluntary standards. But the full potential of savings, estimated at 50\% of current consumption or $100 billion/year, (Bevington and Rosenfeld 1990; Todesco 1996; Holdren 1997; Kolderup and Syphers 1997; ORNL, LBNL et al. 1997) will require that architects and engineers take an integrated look at buildings beginning in the early design phase, with increasing use of sophisticated, complex and interrelated building systems. This puts a greater burden on the designer and engineer to make accurate engineering decisions.

}, author = {Joseph H. Klems and Elizabeth U. Finlayson and Thomas H. Olsen and David W Banks and Jani M. Pallis} } @conference {11520, title = {Advanced Fenestration Systems for Improved Daylight Performance}, booktitle = {Daylighting 98 Conference }, year = {1998}, month = {05/1998}, address = {Ottawa, Canada}, abstract = {

The use of daylight to replace or supplement electric lighting in commercial buildings can result in significant energy and demand savings. High performance fenestration systems are a necessary, but not sufficient, element of any successful daylighting design that reduces lighting energy use. However, these savings may be reduced if the fenestration systems impose adverse thermal loads. New fenestration technologies have been developed over the last twenty years, aiming at controlling the intensity of the incoming solar radiation, its interior distribution and its spectral composition, as well as thermal losses and gains. Some of these have proven successful for specific or general building applications, while others are still under development and testing to understand limitations and potential benefits.

In this paper we review the state of the art of several advanced fenestration systems which, are designed to maximize the energy-saving potential of daylighting while improving comfort and visual performance, at an affordable cost. We first review the key performance issues that successful fenestration systems must address, and then review several classes of fenestration systems intended to meet those performance needs. The systems are reviewed in two categories: static and dynamic. Static systems include not only glazings, such as spectrally selective and holographic glazings, but specialized designs of light-shelves and light-pipes, while dynamic systems cover automatically operated blinds and electrochromic glazings.

We include a discussion of the research directions in this area, and how these efforts might lead to static and dynamic hardware and system solutions that fulfill the multiple roles that these systems must play in terms of energy efficiency, comfort, visual performance, health, and amenity in future buildings.

}, author = {Stephen E. Selkowitz and Eleanor S. Lee} } @article {11766, title = {Effect of Hydrogen Insertion on the Optical Properties of PD-Coated Magnesium Lanthanides}, journal = {Electrochimica Acta}, year = {1998}, month = {9/1998}, address = {London, U.K.}, abstract = {

Metallic magnesium lanthanide thin films upon insertion of hydrogen transform to a highly transparent hydride phase. With a Pd overlayer, the transformation can be produced either by electrochemical insertion of hydrogen or by exposing the film to hydrogen gas. Unlike amorphous oxide electrochromics, the transformation is accompanied by a large change in visible reflectance (about 50\%). The optical switching effect in these materials is investigated in terms of changes in the complex refractive index as determined by variable-angle spectroscopic ellipsometric and normal-incidence radiometric measurements over the solar spectrum. Furthermore the optical effect of converting the Pd caplayer to Pd-H was determined. It is shown that the pd layer limits the visible transmittance of the hyrdrided stack to about 35-40\%. Whereas the extinction coefficient of the dehydrided LnMg-layers at 550 nm is between 2.2 and 3.1, it is as low as 10-4 in the transparent state.

}, author = {Klaus von Rottkay and Michael D. Rubin and Franck Michalak and Robert D. Armitage and Thomas J. Richardson and Jonathan L. Slack and Peter A. Duine} } @article {11774, title = {The Effect of Venetian Blinds on Daylight Photoelectric Control Performance}, journal = {Journal of the Illuminating Engineering Society}, volume = {28}, number = {1}, year = {1998}, abstract = {

We investigate how a venetian blind, a common but optically complex fenestration system, contributes to the unreliable performance of daylighting control systems. Using a fully instrumented, full-scale testbed facility, we monitored the daylighting performance of a modified closed-loop proportional photoelectric control system in a private office over the course of a year. The ratio of workplane illuminance from daylight to photosensor signal is characterized in terms of solar condition and venetian blind angle. Variations in this ratio causes actual illuminance levels to be periodically insufficient. This type of characterization can be used by the installer to determine whether the initial control adjustments made during commissioning will lead to reliable performance under most daylight conditions. Commissioning guidelines are given with caution, based on our observations from this specific case study.

We quantified the effect of variability in this ratio on control performance. With a middle-of-the-road gain constant, monitored workplane illuminance levels did not fall below 90\% of the design setpoint for 91\% of the year. When discrepancies occurred, differences between the daylight correlation and measured conditions were the primary cause of insufficient illuminance at the workplane. This performance is not applicable to commercially-available closed-loop proportional systems because 1) typical systems are rarely commissioned properly upon installation, and 2) off-the-shelf systems combine the photosensor{\textquoteright}s response to daylight and electric light into one gain parameter. Even though the prototype system was subject to the same discrepancies in the daylight correlation fit as commercially-available systems, performance was substantially improved because the prototype was able to separate the electric lighting contribution to workplane illuminance from the daylighting contribution, at no added cost. Commissioning should accommodate the effect of the fenestration system, since variations in luminance distributions produced by the window are the primary cause of unreliable performance.

}, author = {Eleanor S. Lee and Dennis L. DiBartolomeo and Stephen E. Selkowitz} } @article {11792, title = {Electrochromic lithium nickel oxide by pulsed laser deposition and sputtering}, journal = {Solar Energy Materials and Solar Cells}, volume = {54}, number = {4-Jan}, year = {1998}, month = {07/1998}, pages = {59-66}, chapter = {59}, abstract = {

Thin films of lithium nickel oxide were deposited by sputtering and pulsed laser deposition (PLD) from targets of pressed LiNiO2 powder. The composition and structure of these films were analyzed using a variety of techniques, such as nuclear-reaction analysis, Rutherford backscattering spectrometry (RBS), X-ray diffraction, infrared spectroscopy, and atomic-force microscopy. Crystalline structure, surface morphology and chemical composition of LixNi1-xO thin films depend strongly on deposition oxygen pressure, temperature as well as substrate{\textendash}target distance. The films produced at temperatures lower than 600{\textdegree}C spontaneously absorb CO2 and H2O at their surface once they are exposed to the air. The films deposited at 600{\textdegree}C proved to be stable in air over a long period. Even at room temperature the PLD films are denser and more stable than sputtered films. RBS determined the composition of the best films to be Li0.5Ni0.5O deposited by PLD at 60\ mTorr O2 pressure. Electrochemical tests show that the films exhibit excellent reversibility in the range 1.0{\textendash}3.4\ V versus lithium. Electrochemical formatting which is used to develop electrochromism in other films is not needed for the stoichiometric films. The optical transmission range is almost 70\% at 550\ nm for 150\ nm-thick films. Devices made from these films were analyzed using novel reference electrodes and by disassembling after cycling.

}, keywords = {Lithium nickel oxide, pulsed laser deposition, sputtering}, doi = {10.1016/S0927-0248(97)00223-7}, author = {Michael D. Rubin and Shi-Jie Wen and Thomas J. Richardson and John B. Kerr and Klaus von Rottkay and Jonathan L. Slack} } @article {11794, title = {Electrochromic Lithium Nickel Oxide Thin Films by RF-Sputtering from a LiNiO2 Target}, journal = {Electrochimica Acta}, volume = {44}, number = {18}, year = {1998}, pages = {3085-3092}, abstract = {

Thin films of lithium nickel oxide were deposited by rf sputtering from a stoichiometric LiNiO2 target. The composition and structure of these films depended on the oxygen pressure during deposition (sputtering gas is Argon), and, to a certain extent, the target history. The sputtering geometry, i.e. the substrate to target distance and the sputtering angle were also critical. the films exhibit excellent reversibility in the potential range 1.1V to 3.8 V vs Li/Li+ and could be cycled in a liquid electrolyte half cell for more than 3000 cycles with a switching range ΔTvis close to 70\%. The coloration efficiency in the visible was typically -30 to -40 cm2 C-1. The switching performance of a device utilizing a lithium nickel oxide film as counter electrode for a tungsten oxide electrochromic film is reported.

}, author = {Franck Michalak and Klaus von Rottkay and Thomas J. Richardson and Jonathan L. Slack and Michael D. Rubin} } @article {11805, title = {Ellipsometry on Sputter Deposited Tin Oxide Films: Optical Constants Versus Stoichiometry Hydrogen Content, and Amount of Electrochemically Intercalated Lithium}, journal = {Applied Optics}, volume = {37}, number = {31}, year = {1998}, pages = {7734-7741}, abstract = {

Tin oxide thin films were deposited by reactive radio-frequency magnetron sputtering onto In2O3:Sn coated and bare glass substrates. Optical constants in the 300-2500 nm wavelength range were determined by a combination of variable-angle spectroscopic ellipsometry and spectrophotometric transmittance measurements. Surface roughness was modeled from optical measurements and compared with atomic-force microscopy. The two techniques gave consistent results. The fit between experimental optical data and model results could be significantly improved when it was assumed that the refractive index of the Sn oxide varied across the film thickness. Varying the oxygen partial pressure during deposition made it possible to obtain films whose complex refractive index changed at the transition from SnO to SnO2. An addition of hydrogen gas during sputtering led to lower optical constants in the full spectral range in connection with a blue shift of the band gap. Electrochemical intercalation of lithium ions into the Sn oxide films raised their refractive index and enhanced their refractive-index gradient.

}, author = {Jan Isidorsson and Claes G. Granqvist and Klaus von Rottkay and Michael D. Rubin} } @conference {11806, title = {The Elusive Challenge of Daylighted Buildings 25 Years Later}, booktitle = {Daylighting 98 Conference}, year = {1998}, month = {05/1998}, address = {Ottawa, Ontario, Canada}, abstract = {

As we approach the end of the decade of the 1990s, daylighting is increasingly promoted as a design strategy and building solution that can save energy and improve human performance and satisfaction in indoor spaces. Similar claims were made in the 1970s in the aftermath of the oil embargo. Twenty-five years later, in a world newly concerned about carbon emissions, global warming, and sustainable design, daylighted buildings are again proposed as a solution. While it is possible to find some examples of well daylighted buildings that have been built in the last 25 years, the fact that there are so few suggests that the optimistic outlook for daylighting needs to be critically (re)examined.

}, author = {Stephen E. Selkowitz} } @conference {11809, title = {Energy and Daylight Performance of Angular Selective Glazings}, booktitle = {ASHRAE/DOE/BTECC Conference, Thermal Performance of the Exterior Envelopes of Buildings VII}, year = {1998}, month = {12/1998}, address = {Clearwater Beach, FL}, abstract = {

This paper presents the results of a study investigating the energy and daylight performance of anisotropic angular selective glazings. The DOE-2.1E energy simulation program was used to determine the annual cooling, lighting and total electricity use, and peak electric demand. RADIANCE, a lighting simulation program, was used to determine daylight illuminance levels and distribution. We simulated a prototypical commercial office building module located in Blythe, California. We chose three hypothetical conventional windows for comparison: a single-pane tinted window, a double-pane low-E window, and a double-pane spectrally selective window. Daylighting controls were used. No interior shades were modeled in order to isolate the energy effects of the angular selective glazing. Our results show that the energy performance of the prototype angular selective windows is about the same as conventional windows for a 9.14 m (30 ft) deep south-facing perimeter zone with a large-area window in the hot, sunny climate of Blythe. It is theoretically possible to tune the angular selectivity of the glazing to achieve annual cooling energy reductions of 18\%, total electricity use reductions of 15\%, and peak electric demand reductions of 11\% when compared to a conventional glazing with the same solar-optical properties at normal incidence. Angular selective glazings can provide more uniformly distributed daylight, particularly in the area next to the window, which will result in a more visually comfortable work environment.

}, author = {Robert Sullivan and Liliana O. Beltran and Eleanor S. Lee and Michael D. Rubin and Stephen E. Selkowitz} } @conference {11866, title = {Experimental Techniques for Measuring Temperature and Velocity Fields to Improve the Use and Validation of Building Heat Transfer Models}, booktitle = {Thermal Performance of the Exterior Envelopes of Buildings VII}, year = {1998}, month = {12/1998}, address = {Clearwater Beach, FL}, abstract = {

When modeling thermal performance of building components and envelopes, researchers have traditionally relied on average surface heat-transfer coefficients that often do not accurately represent surface heat-transfer phenomena at any specific point on the component being evaluated. The authors have developed new experimental techniques that measure localized surface heat-flow phenomena resulting from convection. The data gathered using these new experimental procedures can be used to calculate local film coefficients and validate complex models of room and building envelope heat flows. These new techniques use a computer controlled traversing system to measure both temperatures and air velocities in the boundary layer near the surface of a building component, in conjunction with current methods that rely on infrared (IR) thermography to measure surface temperatures. Measured data gathered using these new experimental procedures are presented here for two specimens: (1) a Calibrated Transfer Standard (CTS) that approximates a constant-heat-flux, flat plate; and (2) a dual-glazed, low-emittance (low-e), wood-frame window. The specimens were tested under steady-state heat flow conditions in laboratory thermal chambers. Air temperature and mean velocity data are presented with high spatial resolution (0.25- to 25-mm density). Local surface heat-transfer film coefficients are derived from the experimental data by means of a method that calculates heat flux using a linear equation for air temperature in the inner region of the boundary layer. Local values for convection surface heat-transfer rate vary from 1 to 4.5 W/m2K. Data for air velocity show that convection in the warm-side thermal chamber is mixed forced/natural, but local velocity maximums occur from 4 to 8 mm from the window glazing.

}, author = {Brent T. Griffith and Daniel Turler and Howdy Goudey and Dariush K. Arasteh} } @conference {2929, title = {Integrated Performance of an Automated Venetian Blind/Electric Lighting System in a Full-Scale Private Office}, booktitle = {ASHRAE/DOE/BTECC Conference, Thermal Performance of the Exterior Envelopes of Buildings VII}, year = {1998}, month = {09/1998}, address = {Clearwater Beach, FL}, abstract = {

Comprehensive results are presented from a full-scale testbed of a prototype automated venetian blind/lighting system installed in two unoccupied, private offices in Oakland, California. The dynamic system balanced daylight against solar heat gains in real-time, to reduce perimeter zone energy use and to increase comfort. This limited proof-of-concept test was designed to work out practical "bugs" and refine design details to increase cost effectiveness and acceptability of this innovative technology for real-world applications. We present results from 14 months of tuning the system design and monitoring energy performance and control system operations. For this southeast-facing office, we found that 1-22\% lighting energy savings, 13-28\% cooling load reductions, and 13-28\% peak cooling load reductions can be achieved by the dynamic system under clear sky and overcast conditions year round, compared to a static, partly closed blind with the same optimized daylighting control system. These energy savings increase if compared to conventional daylighting controls with manually-operated blinds. Monitored data indicated that the control system met design objectives under all weather conditions to within 10\% for at least 90\% of the year. A pilot human factors study indicated that some of our default control settings should be adjusted to increase user satisfaction. With these adjustments, energy savings will decrease. The final prototype design yielded a 10-year simple payback for this site. If mechanical system downsizing opportunities and qualitative improvements to worker{\textquoteright}s comfort are included, this innovative technology could be more cost effective. Marketing information for commercializing this technology is given.

}, author = {Eleanor S. Lee and Dennis L. DiBartolomeo and Edward L. Vine and Stephen E. Selkowitz} } @article {1675, title = {Office Worker Response to an Automated Venetian Blind and Electric Lighting System: A Pilot Study}, journal = {Energy and Buildings}, volume = {28}, year = {1998}, month = {10/1998}, pages = {205-218}, chapter = {205}, abstract = {

A prototype integrated, dynamic building envelope and lighting system designed to optimize daylight admission and solar heat gain rejection on a real-time basis in a commercial office building is evaluated. Office worker response to the system and occupant-based modifications to the control system are investigated to determine if the design and operation of the prototype system can be improved. Key findings from the study are: (1) the prototype integrated envelope and lighting system is ready for field testing, (2) most office workers (N=14) were satisfied with the system, and (3) there were few complaints. Additional studies are needed to explain how illuminance distribution, lighting quality, and room design can affect workplane illuminance preferences.

}, keywords = {behavior, Comfort, commercial buildings, daylighting, envelope}, doi = {10.1016/S0378-7788(98)00023-1}, author = {Edward L. Vine and Eleanor S. Lee and Robert D. Clear and Dennis L. DiBartolomeo and Stephen E. Selkowitz} } @article {12144, title = {Optical Constants of Sputter-Deposited Ti-Ce Oxide and Zr-Ce Oxide Films}, journal = {Applied Optics}, volume = {37}, number = {25}, year = {1998}, month = {09/1998}, pages = {5993-6001}, chapter = {5993}, abstract = {

Films of Ti oxide, Zr oxide, Ce oxide, Ti-Ce oxide, and Zr-Ce oxide were made by means of reactive dc magnetron sputtering in a multitarget arrangement. The films were characterized by x-ray diffraction and electrochemical measurements, both techniques being firmly connected to stoichiometric information. The optical constants n and k were evalued from spectrophotometry and from variable-angle spectroscopic ellipsometry. The two analyses gave consistent results. It was found that n for the mixed-oxide films varied smoothly between the values for the pure oxides, whereas k in the band-gap range showed characteristic differences between Ti-Ce oxide and Zr-Ce oxide. It is speculated that this difference is associated with structural effects.

}, doi = {10.1364/AO.37.005993}, author = {Monica Veszelei and Lisen Kullman and Claes G. Granqvist and Klaus von Rottkay and Michael D. Rubin} } @conference {12207, title = {Rapid field testing of low-emittance coated glazings for product verification}, booktitle = {ASHRAE/DOE/BTECC Conference, Thermal Performance of the Exterior Envelopes of Buildings VII}, year = {1998}, month = {12/1998}, address = {Clearwater Beach, Florida}, abstract = {

This paper analyzes prospects for developing a test device suitable for field verification of the types of low-emittance (low-e) coatings present on high-performance window products. Test devices are currently available that can simply detect the presence of low-e coatings and that can measure other important characteristics of high-performance windows, such as the thickness of glazing layers or the gap in dual glazings. However, no devices have yet been developed that can measure gas concentrations or distinguish among types of coatings. This paper presents two optical methods for verification of low-e coatings. The first method uses a portable, fiber-optic spectrometer to characterize spectral reflectances from 650 to 1,100 nm for selected surfaces within an insulated glazing unit (IGU). The second method uses an infrared-light-emitting diode and a phototransistor to evaluate the aggregate normal reflectance of an IGU at 940 nm. Both methods measure reflectance in the near (solar) infrared spectrum and are useful for distinguishing between regular and spectrally selective low-e coatings. The infrared-diode/phototransistor method appears promising for use in a low-cost, hand-held field test device.

}, author = {Brent T. Griffith and Christian Kohler and Howdy Goudey and Daniel Turler and Dariush K. Arasteh} } @techreport {58590, title = {Spectrally Selective Glazings}, year = {1998}, month = {08/1998}, pages = {47}, institution = {New Technology Energy Management Program, Federal Energy Management Program}, abstract = {

Spectrally selective glazing is window glass that permits some portions of the solar spectrum to enter a building while blocking others. This high-performance glazing admits as much daylight as possible while preventing transmission of as much solar heat as possible. By controlling solar heat gains in summer, preventing loss of interior heat in winter, and allowing occupants to reduce electric lighting use by making maximum use of daylight, spectrally selective glazing significantly reduces building energy consumption and peak demand. Because new spectrally selective glazings can have a virtually clear appearance, they admit more daylight and permit much brighter, more open views to the outside while still providing the solar control of the dark, reflective energy-efficient glass of the past, as shown in the figures on the left.

Because of its solar heat transmission properties, spectrally selective glazing benefits both buildings in warm climates where solar heat gain can be a problem and buildings in colder climates where solar heat gains in summer and interior heat loss in winter are both of concern. In other words, these glazings are appropriate for residential and commercial buildings throughout the United States. The energy efficiency of spectrally selective glazing means that architects who use it can incorporate more glazing area than was possible in the past within the limitations of codes and standards specifying minimum energy performance. When spectrally selective glazing is used, the capacity of the building{\textquoteright}s cooling system can also be downsized because of reduced peak loads.

Spectrally selective glazings screen out or reflect heat-generating ultraviolet and infrared radiation arriving at a building{\textquoteright}s exterior surface while permitting most visible light to enter. Spectral selectivity is achieved by a microscopically thin, low-emissivity (low-E) coating on the glass or on a film applied to the glass. There are also carefully engineered types of blue- and green-tinted glass that can perform as well in a double-pane unit as some glass with a low-E coating. Conventional blue- and green-tinted glass can offer some of the same spectral properties as these special absorbers because impurities in tinted glass absorb portions of the solar spectrum. Absorption is less efficient than reflection, however, because heat absorbed by tinted glass continues to radiate to the building{\textquoteright}s interior.

This technology is most costeffective for residential and nonresidential facilities that have high cooling loads, high utility rates, poorly performing existing glazing (such as single-pane clear glass or dark tinted glass), or are located in the southern United States. In the northern United States, spectrally selective low-E windows can also be cost-effective for buildings with both heating and cooling requirements.

In general, the technology pays back in 3 to 10 years for U.S. commercial buildings where it replaces clear single-pane or tinted doublepane glass and for most commercial buildings in the southern United States where it replaces low-E, double-pane windows. Spectrally selective glazing is applicable in both new and retrofit construction.

This Federal Technology Alert provides detailed information and procedures for Federal energy managers to consider spectrally selective glazings. The principle of spectrally selective glazings is explained. Benefits related to energy efficiency and other architectural criteria are delineated. Guidelines are provided for appropriate application of spectrally selective glazing, and step-by-step instructions are given for estimating energy savings. Case studies are also presented to illustrate actual costs and energy savings. Current manufacturers, technology users, and references for further reading are included for users who have questions not fully addressed here.

}, author = {Eleanor S. Lee} } @conference {1847, title = {State-of-the-Art Software for Window Energy-Efficiency Rating and Labeling}, booktitle = {ACEEE 1998 Summer Study on Energy Efficiency in Buildings}, year = {1998}, month = {08/1998}, address = {Pacific Grove, CA}, abstract = {

Measuring the thermal performance of windows in typical residential buildings is an expensive proposition. Not only is laboratory testing expensive, but each window manufacturer typically offers hundreds of individual products, each of which has different thermal performance properties. With over a thousand window manufacturers nationally, a testing-based rating system would be prohibitively expensive to the industry and to consumers.

Beginning in the early 1990s, simulation software began to be used as part of a national program for rating window U-values. The rating program has since been expanded to include Solar Hear Gain Coefficients and is now being extended to annual energy performance.

This paper describes four software packages available to the public from Lawrence Berkeley National Laboratory (LBNL). These software packages are used to evaluate window thermal performance: RESFEN (for evaluating annual energy costs), WINDOW (for calculating a products thermal performance properties), THERM (a preprocessor for WINDOW that determines two-dimensional heat-transfer effects), and Optics (a preprocessor for WINDOWs glass database).

Software not only offers a less expensive means than testing to evaluate window performance, it can also be used during the design process to help manufacturers produce windows that will meet target specifications. In addition, software can show small improvements in window performance that might not be detected in actual testing because of large uncertainties in test procedures.

}, author = {Dariush K. Arasteh and Elizabeth U. Finlayson and Yu Joe Huang and Charlie Huizenga and Robin Mitchell and Michael D. Rubin} } @article {1880, title = {Teaching Students about Two-Dimensional Heat Transfer Effects in Buildings, Building Components, Equipment, and Appliances Using THERM 2.0}, journal = {ASHRAE Transactions}, volume = {105, Part 1}, year = {1998}, month = {01/1999}, address = {Chicago, IL}, abstract = {

THERM 2.0 is a state-of-the-art software program, available for free, that uses the finite-element method to model steady-state, two-dimensional heat-transfer effects. It is being used internationally in graduate and undergraduate laboratories and classes as an interactive educational tool to help students gain a better understanding of heat transfer. THERM offers students a powerful simulation engine combined with a simple, interactive interface and graphic results. Although it was developed to model thermal properties of building components such as windows, walls, doors, roofs, and foundations, it is useful for modeling thermal bridges in many other contexts, such as the design of equipment. These capabilities make THERM a useful teaching tool in classes on: heating, ventilation, and air-conditioning (HVAC); energy conservation; building design; and other subjects where heat-transfer theory and applications are important. THERMs state-of-the-art interface and graphic presentation allow students to see heat-transfer paths and to learn how changes in materials affect heat transfer. THERM is an excellent tool for helping students understand the practical application of heat-transfer theory.

}, author = {Charlie Huizenga and Dariush K. Arasteh and Elizabeth U. Finlayson and Robin Mitchell and Brent T. Griffith} } @techreport {1891, title = {THERM 2.0: a PC Program for Analyzing Two-Dimensional Heat Transfer through Building products}, year = {1998}, abstract = {

THERM is a state-of-the-art, Microsoft Windows?-based computer program developed at Lawrence Berkeley National Laboratory (LBNL) for use by building component manufacturers, engineers, educators, students, architects, and others interested in heat transfer. Using THERM, you can model two-dimensional heat-transfer effects in building components such as windows, walls, foundations, roofs, and doors; appliances; and other products where thermal bridges are of concern. THERM{\textquoteright}s heat-transfer analysis allows you to evaluate a product?s energy efficiency and local temperature patterns, which may relate directly to problems with condensation, moisture damage, and structural integrity.

This version of THERM includes several new technical and user interface features; the most significant is a radiation view-factor algorithm. This feature increases the accuracy of calculations in situations where you are analyzing non-planar surfaces that have different temperatures and exchange energy through radiation heat transfer. This heat-transfer mechanism is important in greenhouse windows, hollow cavities, and some aluminum frames.

}, author = {Elizabeth U. Finlayson and Robin Mitchell and Dariush K. Arasteh and Charlie Huizenga and Dragan C. Curcija} } @conference {1932, title = {Tungsten-Vanadium Oxide Sputtered Films for Electrochromic Devices}, booktitle = {Electrochemical Society: Molecular Functions of Electroactive Thin Films}, volume = {98-26}, year = {1998}, month = {11/1998}, address = {Boston, MA}, abstract = {

Mixed vanadium and tungsten oxide films with compositions ranging from 0 to 100\% vanadium (metals basis) were prepared by reactive sputtering from metallic vanadium and tungsten targets in an atmosphere of argon and oxygen. The vanadium content varied smoothly with the fraction of total power applied to the vanadium target. Films containing vanadium were more color neutral than pure tungsten oxide films, tending to gray-brown at high V fraction. The electrochromic switching performance of these films was investigated by in situ monitoring of their visible transmittance during lithium insertion/extraction cycling in a non-aqueous electrolyte (1M LiClO4 in PC). the solar transmittance and reflectance was measured ex-situ. Films with vanadium content greater than about 15\%, exhibited a marked decrease in switching range. The coloration efficiencies followed a similar trend.

}, author = {Thomas J. Richardson and Klaus von Rottkay and Jonathan L. Slack and Franck Michalak and Michael D. Rubin} } @techreport {1951, title = {Validation studies of the DOE-2 Building Energy Simulation Program. Final Report}, year = {1998}, abstract = {

This report documents many of the validation studies (Table 1) of the DOE-2 building energy analysis simulation program that have taken place since 1981. Results for several versions of the program are presented with the most recent study conducted in 1996 on version DOE-2.1E and the most distant study conducted in 1981 on version DOE-1.3. This work is part of an effort related to continued development of DOE-2, particularly in its use as a simulation engine for new specialized versions of the program such as the recently released RESFEN 3.1. RESFEN 3.1 is a program specifically dealing with analyzing the energy performance of windows in residential buildings. The intent in providing the results of these validation studies is to give potential users of the program a high degree of confidence in the calculated results.

}, author = {Robert Sullivan and Frederick C. Winkelmann} } @article {11528, title = {Advanced Optical Daylighting Systems: Light Shelves and Light Pipes}, journal = {1996 IESNA Annual Conference}, volume = {26}, year = {1997}, note = {

Presented at the 1996 IESNA Annual Conference
Cleveland, OH,
August 4-7, 1996

}, pages = {91-106}, chapter = {91}, address = {Cleveland, OH}, abstract = {

We present two perimeter daylighting systems that passively redirect beam sunlight further from the window wall using special optical films, an optimized geometry, and a small glazing aperture. The objectives of these systems are (1) to increase daylight illuminance levels at 4.6-9.1 m (15-30 ft) from the window aperture with minimum solar heat gains and (2) to improve the uniformity of the daylighting luminance gradient across the room under variable solar conditions throughout the year. The designs were developed through a series of computer-assisted ray-tracing studies, laser visualization techniques, and photometric measurements and observations using physical scale models. Bi-directional illuminance measurements in combination with analytical routines were then used to simulate daylight performance for any solar position, and were incorporated into the DOE-2.1E building energy analysis computer program to evaluate energy savings. Results show increased daylight levels and an improved luminance gradient throughout the year compared to conventional daylighting systems.

}, doi = {10.1080/00994480.1997.10748194}, author = {Liliana O. Beltran and Eleanor S. Lee and Stephen E. Selkowitz} } @article {11544, title = {Analysis of Binary Electrochromic Tungsten Oxides with Effective Medium Theory}, journal = {Thin Solid Films}, volume = {308-309}, year = {1997}, pages = {50-55}, abstract = {

Multicomponent oxides are of increasing interest for electrochromic electrodes. To reduce the large number of permutations in composition it would be useful to be able to predict the properties of the mixtures from the pure oxide components. WO3 mixed with V2O5 has been produced by a sol-gel technique in order to increase durability and color neutrality of conventional WO3 electrochromic coatings. Chemical composition was confirmed by Rutherford backscattering spectrometry (RBS). Surface morphology was analyzed by atomic force microscopy (AFM). Electrochromic performance of the films was tested by cyclic voltammetry with in-situ transmission control. Optical constants of vanadium tungsten oxides were determined over the whole solar spectrum. The measurements included variable angle spectroscopic ellipsometry and spectral transmittance and reflectance. An attempt is made to treat doped tungsten oxide as an effective medium consisting of a mixture of WO3 with V2O5. In the clear state, comparison of optical constants and thickness directly determined on the samples yields qualitative agreement with results from effective-medium analysis. The resulting component fraction also agrees as long as the film density does not deviate too much from the linearly interpolated value between the pure components. For the colored state, preferential trapping of electrons at one atom species hinders the application of effective medium theory.

}, author = {Klaus von Rottkay and Nilg{\"u}n {\"O}zer and Michael D. Rubin and Thomas J. Richardson} } @article {2882, title = {Building Design Advisor: Automated Integration of Multiple Simulation Tools}, journal = {Automation in Construction}, volume = {6}, number = {4}, year = {1997}, month = {08/1997}, pages = {341-352}, publisher = {Elsevier}, chapter = {341}, abstract = {

The Building Design Advisor (BDA) is a software environment that supports the integrated use of multiple analysis and visualization tools throughout the building design process, from the initial, conceptual and schematic phases to the detailed specification of building components and systems. Based on a comprehensive design theory, the BDA uses an object-oriented representation of the building and its context, and acts as a data manager and process controller to allow building designers to benefit from the capabilities of multiple tools.

The BDA provides a graphical user interface that consists of two main elements: the Building Browser and the Decision Desktop. The Browser allows building designers to quickly navigate through the multitude of descriptive and performance parameters addressed by the analysis and visualization tools linked to the BDA. Through the Browser the user can edit the values of input parameters and select any number of input and/or output parameters for display in the Decision Desktop. The Desktop allows building designers to compare multiple design alternatives with respect to multiple descriptive and performance parameters addressed by the tools linked to the BDA.

The BDA is implemented as a Windows{\textregistered}-based application for personal computers. Its initial version is linked to a Schematic Graphic Editor (SGE), which allows designers to quickly and easily specify the geometric characteristics of building components and systems. For every object created in the SGE, the BDA activates a Default Value Selector (DVS) mechanism that selects "smart" default values from a Prototypes Database for all non-geometric parameters required as input to the analysis and visualization tools linked to the BDA. In addition to the SGE that is an integral part of its user interface, the initial version of the BDA is linked to a daylight analysis tool, an energy analysis tool, and a multimedia, Web-based Case Studies Database (CSD). The next version of the BDA will be linked to additional analysis tools, such as the DOE-2 (thermal, energy and energy cost) and RADIANCE (day/lighting and rendering) computer programs. Plans for the future include the development of links to cost estimating and environmental impact modules, building rating systems, CAD software and electronic product catalogs.

}, doi = {10.1016/S0926-5805(97)00043-5}, author = {Konstantinos M. Papamichael and John LaPorta and Hannah L. Chauvet} } @conference {2869, title = {Design and Performance of an Integrated Envelope/Lighting System}, booktitle = {ICBEST {\textquoteright}97 International Conference on Building Envelope Systems and Technology}, year = {1997}, month = {04/1997}, pages = {375-380}, address = {Bath, UK}, abstract = {

Dynamic envelope/lighting systems offer the potential to achieve a near optimum energy-efficient environment meeting occupant needs throughout the year by adapting to dynamic meteorological conditions and changing occupant preferences in real time. With the dramatic increased functionality of the microprocessor, there is an untapped potential to make dynamic envelope/lighting systems easier to use, diagnose, and monitor, and to integrate them as part of a sophisticated building-wide control system. This study addresses the complex relationship between this energy-efficiency technology and many of the non-energy issues related to its potential acceptance by the building industry, architects, owners, and users. We demonstrate the concept of integrated dynamic systems with a prototype motorized venetian blind operated in synchronization with electric lighting and daylighting controls via an intelligent control system. Research work conducted with simulation software and reduced-scale and full-scale field tests is summarized. Much of this work is directly relevant to other active shading and daylighting systems on the market today and to state-of-the-art window systems yet to come (i.e., electrochromics).

}, author = {Eleanor S. Lee and Stephen E. Selkowitz} } @conference {11778, title = {Effective Medium Approximation of the Optical properties of electrochromic cerium-titanium oxide compounds}, booktitle = {SPIE Proceedings}, volume = {3138}, year = {1997}, month = {07/1997}, pages = {19-Sep}, address = {San Diego, CA}, abstract = {

Cerium titanium oxide samples derived from a solution have been compared against sputtered films over a wide range of different compositions. X-ray diffraction was used to investigate the structural properties of the compound material existing in a two-phase mixture MAO2-MBO2. The optical properties were evaluated over the whole solar spectrum by variable angle spectroscopic ellipsometry combined with spectrophutometry. The spectral complex refractive index was determined for CeO2 and TiO2, as well as for their compounds. To reduce the large number of permutations in composition of multi-component oxides it would be useful to be able to predict the properties of the mixtures from the pure oxide components. Therefore these results were compared to those obtained by effective medium theory utilizing the optical constants of CeO2 and TiO2. In order to investigate the performance as passive counter-electrode in Li+ based electrochromic devices the films were tested by cyclic voltammetry with in-situ transmission control. Chemical composition was measured by Rutherford backscattering spectrometry. Surface morphology was analyzed by atomic force microscopy.

}, keywords = {cerium titanium oxide, effective medium theory, electrochromic, optical constants}, author = {Klaus von Rottkay and Thomas J. Richardson and Michael D. Rubin and Jonathan L. Slack} } @article {11904, title = {Greenhouse Window U-Factors Under Field Conditions}, journal = {ASHRAE Transactions}, volume = {104, Part 1}, year = {1997}, month = {01/1998}, address = {San Francisco, CA}, abstract = {

Field measurements of U-factor are reported for two projecting greenhouse windows, each paired with a picture window of comparable insulation level during testing. A well-known calorimetric field test facility was used to make the measurements. The time-varying U-factors obtained are related to measurements of exterior conditions. For one of the greenhouse windows, which was the subject of a published laboratory hotbox test and simulation study, the results are compared with published test and simulation data and found to be in disagreement. Data on interior and exterior film coefficients are presented, and it is shown that the greenhouse window has a significantly lower interior film coefficient than a conventional window under the same interior conditions. This is advanced as a possible explanation of the disagreement.

}, author = {Joseph H. Klems} } @article {11906, title = {Guidelines for Modeling Projecting Fenestration Products}, journal = {ASHRAE Transactions}, volume = {104, Part 1}, year = {1997}, month = {01/1998}, address = {San Francisco, CA}, abstract = {

Heat transfer patterns in projecting fenestration products (greenhouse windows, skylights, etc.) are different than those with typical planar window products. The projecting surfaces often radiate to each other, thereby invalidating the commonly used assumption that fenestration product interior surfaces radiate to a uniform room air temperature. The convective portion of the surface heat transfer coefficient is also significantly different from the one used with planar geometries, and is even more dependent on geometry and location. Projecting fenestration product profiles must therefore be modeled in their entirety. This paper presents the results of complete cross section, variable film-coefficient, 2-D heat transfer modeling of two greenhouse windows using the next generation of window specific heat transfer modeling tools. The use of variable film-coefficient models is shown to increase the accuracy with which simulation tools can compute U-factors. Simulated U-factors are also determined using conventional constant film coefficient algorithms. The results from both sets of simulations are compared with measured values.

}, author = {Dariush K. Arasteh and Elizabeth U. Finlayson and Dragan C. Curcija and Jeff Baker and Charlie Huizenga} } @article {11949, title = {Improving Computer Simulations of Heat Transfer for Projecting Fenestration products: Using Radiation View-Factor Models}, journal = {ASHRAE Transactions}, volume = {104, Part 1}, number = {Part 1}, year = {1997}, abstract = {

The window well formed by the concave surface on the warm side of skylights and garden windows can cause surface heat-flow rates to be different for these projecting types of fenestration products than for normal planar windows. Current methods of simulating fenestration thermal conductance (U-value) use constant boundary condition values for overall surface heat transfer. Simulations that account for local variations in surface heat transfer rates (radiation and convection) may be more accurate for rating and labeling window products whose surfaces project outside a building envelope. This paper, which presents simulation and experimental results for one projecting geometry, is the first step in documenting the importance of these local effects.

A generic specimen, called the foam garden window, was used in simulations and experiments to investigate heat transfer of projecting surfaces. Experiments focused on a vertical cross section (measurement plane) located at the middle of the window well on the warm side of the specimen. The specimen was placed between laboratory thermal chambers that were operated at American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) winter heating design conditions. Infrared thermography was used to map surface temperatures. Air temperature and velocity were mapped throughout the measurement plane using a mechanical traversing system. Finite-element computer simulations that directly modeled element-to-element radiation were better able to match experimental data than simulations that used fixed coefficients for total surface heat transfer. Air conditions observed in the window well suggest that localized convective effects were the reason for the difference between actual and modeled surface temperatures. U-value simulation results were 5 to 10\% lower when radiation was modeled directly.

}, author = {Brent T. Griffith and Dragan C. Curcija and Daniel Turler and Dariush K. Arasteh} } @conference {11966, title = {Influence of stoichiometry on the electrochromic cerium-titanium oxide compounds}, booktitle = {11th International Conference of Solid State Ionics}, year = {1997}, month = {11/1997}, address = {Honolulu, Hawaii}, abstract = {

CeO2-TiO2 finds use as passive counter-electrode in electrochromic devices. Thin films were produced by dc-sputtering in a wide range of compositions. Influence of total pressure and oxygen partial pressure on the optical constants of TiO2 was investigated. Slightly substoichiometric TiO2 films exhibit a red-shift of the bandgap. The TiO2 content in the compound essentially determines the degree of cathodical coloring upon Li+ intercalation. However, pure TiO2 films with comparable visible transmittance in the clear state behave differently during electrochemical cycling depending on oxygen stoichiometry. Films that are deposited at higher total pressure are more oxygen rich and require initial formatting until current voltage cycles become stable. CeO2-TiO2 films of intermediate compositions have the relatively highest charge capacity. Comparison with atomic force microscopy indicates a correlation of small grain size with high charge capacity.

}, keywords = {band gap, charge capacity, electrochromic cerium titanium oxide, grain size, optical constants, rms roughness, tio2}, author = {Klaus von Rottkay and Thomas J. Richardson and Michael D. Rubin and Jonathan L. Slack and Lisen Kullman} } @article {12196, title = {Pressure Controlled GaN MBE Growth Using a Hollow Anode Nitrogen Ion Source}, journal = {Materials Research Society Proceedings}, volume = {449}, year = {1997}, note = {

1996 MRS Fall Meeting

}, abstract = {

GaN films were grown on sapphire substrates at temperatures below 1000 K utilizing a Hollow Anode nitrogen ion source. A Ga flux limited growth rate of ~0.5 μm/h is demonstrated. Active utilization of strain and the assistance of a nitrogen partial pressure during buffer layer growth are found to be crucial issues that can improve the film quality. The best films exhibit a full width at half maximum of the x-ray rocking curves of 80 arcsec and 1.85 meV for the excitonic photoluminescence measured at 4 K. A Volmer-Weber three dimensional growth mode and the spontaneous formation of cubic GaN inclusions in the hexagonal matrix are observed in the investigated growth temperature range. It is argued that this growth mode contributes to a limitation of the carrier mobility in these films that did not exceed 120 cm2/Vs through a minimum canier concentration of ~1015 cm-3 was achieved.

}, doi = {10.1557/PROC-449-221}, author = {Michael S.H. Leung and Ralf Klockenbrink and Christian F. Kisielowski and Hiroaki Fujii and Joachim Kr{\"u}ger and Sudhir G. Subramanya and Andr{\'e} Anders and Zuzanna Liliental-Weber and Michael D. Rubin and Eicke R. Weber}, editor = {Joachim Kr{\"u}ger} } @techreport {58587, title = {RESFEN 3.0: A PC Program for Calculating the Heating and Cooling Energy Use of Windows in Residential Buildings}, year = {1997}, month = {12/1997}, pages = {38}, institution = {Lawrence Berkeley National Laboratory}, abstract = {

Today{\textquoteright}s energy-efficient windows can dramatically lower the heating and cooling costs associated with windows while increasing occupant comfort and minimizing window surface condensation problems. However, consumers are often confused about how to pick the most efficient window for their residence. They are typically given window properties such as U-factors or R-values, Solar Heat Gain Coefficients or Shading Coefficients, and air leakage rates. However, the relative importance of these properties depends on the site and building specific conditions. Furthermore, these properties are based on static evaluation conditions that are very different from the real situation the window will be used in. Knowing the energy and associated cost implications of different windows will help consumers and builders make the best decision for their particular application, whether it is a new home, an addition, or a window replacement.

A computer tool such as RESFEN can help consumers and builders pick the most energy-efficient and cost-effective window for a given application. It calculates the heating and cooling energy use and associated costs as well as the peak heating and cooling demand for specific window products. Users define a problem by specifying the house type (single story or two story), geographic location, orientation, electricity and gas cost, and building configuration details (such as wall type, floor type, and HVAC systems). Window options are defined by specifying the window{\textquoteleft}s size, shading, and thermal properties: U-factor, Solar Heat Gain Coefficient, and air leakage rate. RESFEN calculates the energy and cost implications of the windows compared to insulated walls. The relative energy and cost impacts of two different windows can be compared against each other.

RESFEN 3.0 is a major improvement over previous versions of RESFEN because it performs hourly calculations using a version of the DOE 2.1E energy analysis simulation program.

}, author = {Yu Joe Huang and Robert Sullivan and Dariush K. Arasteh and Robin Mitchell} } @article {1794, title = {The Significance of Bolts in the Thermal Performance of Curtain-Wall Frames for Glazed Fa{\c c}ades}, journal = {ASHRAE Transactions}, volume = {104, Part 1}, year = {1997}, month = {01/1998}, address = {San Francisco, CA}, abstract = {

Curtain walls are assemblies of glazings and metal frames that commonly form the exterior glass fa{\c c}ades of commercial buildings. Evaluating the thermal performance of the bolts that hold curtain wall glazings in place is necessary to accurately rate the overall thermal performance of curtain walls. Using laboratory tests and computer simulations, we assessed the thermal performance of several different configurations of bolts and glazings. Curtain-wall samples were tested in the infrared thermography laboratory at the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, California. Experimental results were compared to two-dimensional simulations approximating the thermal effect of the bolts using the parallel path and the isothermal planes calculation methods. We conclude that stainless steel bolts minimally affect curtain-wall thermal performance (approximately 18\%) when spaced at least nine inches apart, which is the industry standard. Performance is increasingly compromised when there is less than nine inches between bolts or when steel bolts are used. We also show that the isothermal planes method of approximating curtain wall thermal performance can be used with 2-D heat transfer software typical of that used in the window industry to give conservative results for the thermal bridging effect caused by bolts.

}, author = {Brent T. Griffith and Elizabeth U. Finlayson and Mehry Yazdanian and Dariush K. Arasteh} } @article {1804, title = {Simulating the Visual Performance of Electrochromic Glazing for Solar Control}, journal = {Journal of the Illuminating Engineering Society}, volume = {27}, number = {2}, year = {1997}, abstract = {

A new technology called electrochromic glazing promises to provide the building industry with a means to dynamically control the visual appearance and solar gain of windows. Electrochromic glazing is a technology which allows an otherwise ordinary looking piece of laminated glass to change tint with the application of a small electrical charge. Prototype electrochromic devices have been produced in sizes up to one square foot, however, manufacturers are several years away from producing glazing samples large enough to fill the aperture of a typical perimeter office. Tooling up for the production of large samples is prohibitively expensive unless some assurance of the marketability of these new electrochromic products can be demonstrated.

Electrochromic glazings defy traditional performance rating mechanisms because of the temporal dimension of their thermal and visual characteristics. Every electrochromic glazing assembly has an infinite number of states at which the thermal and visual appearance could be characterized. Furthermore, the rate at which the assembly changes between states is vital for a complete understanding.

}, author = {Charles K. Ehrlich} } @article {2867, title = {Thermal and Daylighting of an Automated Venetian Blind and Lighting System in a Full-Scale Private Office}, journal = {Energy and Buildings}, volume = {29}, number = {1}, year = {1997}, month = {07/01/1997}, pages = {47-63}, abstract = {

Dynamic envelope/lighting systems have the potential to optimize the perimeter zone energy balance between daylight admission and solar heat gain rejection on a real-time basis, and to increase occupant comfort. Two side-by-side full-scale offices in Oakland, California were built to further develop and test this concept. An automated venetian blind was operated in synchronization with a dimmable electric lighting system to block direct sun, provide the design workplane illuminance, and maximize view. The research program encompassed system design refinements, energy measurements, and human factors tests. In this study, we present lighting energy and cooling load data that were monitored in this facility over the course of a year. Significant energy savings and peak demand reductions were attained with the automated venetian blind/ lighting system compared to a static venetian blind with the same dimmable electric lighting system. Correlations between key weather parameters and cooling and lighting were used to illustrate how the dynamic system was able to simultaneously achieve optimization between lighting and cooling end uses under the full range of weather conditions of this sunny, moderate climate. Energy-efficiency estimates were conservative since experience shows that conventional daylighting control systems and manually operated shading devices are rarely used effectively in real world applications.

}, author = {Eleanor S. Lee and Dennis L. DiBartolomeo and Stephen E. Selkowitz} } @techreport {1913, title = {Tips for Daylighting with Windows: The Integrated Approach}, year = {1997}, abstract = {

These guidelines provide an integrated approach to the cost-effective design of perimeter zones in new commercial buildings. They function as a quick reference for designers through a set of easy steps and rules-of-thumb, emphasizing "how-to" practical details. References are given to more detailed sources of information, should the reader wish to go further.

No guidelines can answer all possible questions from all types of users. However, this document addresses the most commonly occurring scenarios. The guidance here is limited by the medium; short paper documents can only go so far in assisting a designer with a unique project. This document has been carefully shaped to best meet the needs of a designer when time does not permit a more extensive form of assistance.

The design method used in this document emphasizes that building decisions should be made within the context of the whole building as a single functioning system rather than as an assembly of distinct parts. This integrated design approach looks at the ramifications of each individual system decision on the whole building. For example, the glazing selection will have an effect on lighting, mechanical, and interior design. Therefore, the entire design team should participate in and influence this decision{\textemdash}which typically rests with the architect alone. The benefit of an integrated design approach is a greater chance of success towards long term comfort and sustained energy savings in the building.

}, author = {Jennifer O{\textquoteright}Conner and Eleanor S. Lee and Francis M. Rubinstein and Stephen E. Selkowitz} } @article {1974, title = {Window Optics}, journal = {Solar Energy}, volume = {62}, number = {3}, year = {1997}, pages = {149-161}, abstract = {

Optical and radiative properties of glazing materials are primary inputs for determination of energy performance in buildings. This paper revisits the problem and reformulates the calculations to encompass a variety of solutions to practical problems in window optics. Properties of composite systems such as flexible films applied to rigid glazing and laminated glazing can be predicted from measurements on isolated components in air or other gases. Properties of a series of structures can be generated from those of a base structure. For example, the measured properties of a coated or uncoated substrate can be extended to a range of available substrate thicknesses without the need to measure each thickness. Similarly, a coating type could be transferred by calculation to any other substrate. A simple monolithic model for extrapolating from normal properties to oblique properties is shown to have sufficient accuracy for the purpose of annual energy performance calculations. A process is initiated to develop a reliable method for determination of effective indices suitable for more detailed spectral and directional optical calculations.

}, author = {Michael D. Rubin and Klaus von Rottkay and Rebecca Powles} } @conference {11545, title = {Analysis of Durability in Lithium Nickel Oxide Electrochromic Materials and Devices}, booktitle = {2nd International Meeting on Electrochromism}, year = {1996}, month = {10/1996}, address = {San Diego, CA}, abstract = {

Thin films of lithium nickel oxide were deposited by sputtering and laser ablation from targets of pressed nickel oxide and lithium oxide powders. These films were assembled into electrochromic test devices with tungsten oxide as the opposite electrode and a polymer electrolyte. Analysis of the failure modes was carried out at several levels: The composition and structure of the films were examined before and after cycling using a variety of techniques, such as infrared spectroscopy, nuclear-reaction analysis, Rutherford backscattering spectrometry, x-ray diffraction and atomic force microscopy. Absorption of water vapor was found to be a major factor determining the cyclic stability of the films. A new technique is described for incorporating reference electrodes made from an electronically isolated corner into devices. This structure enabled identification of potential problems associated with a particular interface. Finally, some of the devices were disassembled and the components examined. For example, a small quantity of the polymer was extracted and studied by gas chromatography and mass spectroscopy. Small organic fragments were discovered which correspond to expected weak points in the polymer structures.

}, author = {Shi-Jie Wen and John B. Kerr and Michael D. Rubin and Jonathan L. Slack and Klaus von Rottkay} } @conference {2884, title = {The Building Design Advisor}, booktitle = {ACADIA 1996 Conference}, year = {1996}, month = {03/1996}, address = {Tucson, AZ}, abstract = {

The Building Design Advisor (BDA) is a software environment that supports the integrated use of multiple analysis and visualization tools throughout the building design process, from the initial, schematic design phases to the detailed specification of building components and systems. Based on a comprehensive design theory, the BDA uses an object-oriented representation of the building and its context, and acts as a data manager and process controller to allow building designers to benefit from the capabilities of multiple tools. The BDA provides a graphical user interface that consists of two main elements: the Building Browser and the Decision Desktop. The Browser allows building designers to quickly navigate through the multitude of descriptive and performance parameters addressed by the analysis and visualization tools linked to the BDA. Through the Browser the user can edit the values of input parameters and select any number of input and/or output parameters for display in the Decision Desktop. The Desktop allows building designers to compare multiple design alternatives with respect to any number of parameters addressed by the tools linked to the BDA. The BDA is implemented as a Windows{\texttrademark}-based application for personal computers. Its initial version is linked to a Schematic Graphic Editor (SGE), which allows designers to quickly and easily specify the geometric characteristics of building components and systems. For every object created in the SGE, the BDA supplies モsmartヤ default values from a Prototypical Values Database (PVD) for all non-geometric parameters required as input to the analysis and visualization tools linked to the BDA. In addition to the SGE and the PVD, the initial version of the BDA is linked to a daylight analysis tool, an energy analysis tool, and a multimedia Case Studies Database (CSD). The next version of the BDA will be linked to additional tools, such as a photo-accurate rendering program and a cost analysis program. Future versions will address the whole building life-cycle and will be linked to construction, commissioning and building monitoring tools.

}, author = {Konstantinos M. Papamichael and John LaPorta and Hannah L. Chauvet and Deirdre Collins and Thomas Trzcinski and Jack A. Thorpe and Stephen E. Selkowitz} } @conference {11703, title = {Demonstration of a Light-Redirecting Skylight System at the Palm Springs Chamber of Commerce}, booktitle = {1996 ACEEE Summer Study on Energy Efficiency in Buildings: Profiting from Energy Efficiency}, year = {1996}, month = {08/1996}, address = {Pacific Grove, CA}, abstract = {

As part of a demonstration project to provide a comprehensive energy upgrade to a 294 m2 (3168 ft2) commercial building, an advanced skylight design was developed using optical light control materials and geometry to provide daylight to two adjoining offices. The skylight system was developed using outdoor physical model tests and simulation tools Limited on-site measurements and occupant polls were conducted. Market issues were addressed. The skylight systems were found to improve lighting quality and to control excessive daylight illuminance levels compared to a conventional diffusing bubble skylight. Daylighting principles developed in earlier work for vertical glazing systems (light shelves and light pipes) were shown to be applicable in skylight designs at full-scale.

}, author = {Eleanor S. Lee and Liliana O. Beltran and Stephen E. Selkowitz} } @techreport {1254, title = {Design and Evaluation of Daylighting Applications of Holographic Glazings}, year = {1996}, abstract = {

When combined with appropriate electric lighting dimming controls, the use of daylight for ambient and task illumination can significantly reduce energy requirements in commercial buildings. While skylights can effectively illuminate any part of one-story buildings, conventional side windows can illuminate only a 15 ft - 20 ft (4.6 m - 6.1 m) depth of the building perimeter. Even so, the overall efficacy of daylight is limited, because side windows produce uneven distributions of daylight. Achieving adequate illumination at distances further away from the window results in excessive illumination near the window, which increases cooling loads from the associated solar heat gain. As a result, the use of larger apertures and/or higher transmittance glazings, to introduce daylight deeper than 15 ft - 20 ft (4.6 m - 6.1 m), may prove ineffective with respect to saving energy, because cooling load penalties may exceed the electric lighting savings.

The need for more uniform distribution of daylight admitted through side windows has stimulated significant research and development efforts in new fenestration designs and glazing technologies. Many of these approaches, including holographic glazings, rely on the common strategy of redirecting sunlight and reflecting it off the ceiling towards the back of the room. Prior studies on the daylight and energy performance of holographic glazings have been disappointing, however inconclusive because of poor hologram quality, low diffraction efficiency and inadequate hologram design and building application considerations [Papamichael et al 1994].

}, author = {Konstantinos M. Papamichael and Charles K. Ehrlich and Gregory J. Ward} } @article {2850, title = {Developing a Dynamic Envelope/Lighting Control System with Field Measurements}, journal = {Journal of the Illuminating Engineering Society}, volume = {26}, number = {1}, year = {1996}, month = {05/1996}, pages = {146-164}, abstract = {

The feasibility of an intelligent venetian blind/lighting control system was tested in a 1:3 scale model outdoors under variable sun and sky conditions. The control algorithm, block direct sun and meet the design workplane illuminance level, was implemented using commercially available and custom designed blind and lighting systems hardware. While blocking direct sunlight, the blinds were properly controlled to maintain the design workplane illuminance within a tolerance of -10\%, +25\% when there was sufficient daylight. When daylight levels alone were inadequate, the electric lighting control system maintained the design workplane illuminance. The electric lighting could be turned off if a user-specified time period at minimum power was exceeded. Lighting energy savings of 51-71\% (southwest) and 37-75\% (south) was attained for the period from 8:00 to 17:00 on clear sunny days, compared to a fixed, partially closed blind with the same lighting system. Practical details for implementation and commissioning are discussed. The impact of control variations, such as profile angle, time step interval, and control area, on energy demand is investigated.

}, author = {Dennis L. DiBartolomeo and Eleanor S. Lee and Francis M. Rubinstein and Stephen E. Selkowitz} } @conference {11793, title = {Electrochromic Lithium Nickel Oxide Thin Film by Pulsed Laser Deposition}, booktitle = {Electrochemical Society Meeting}, volume = {96-24}, year = {1996}, month = {10/1996}, pages = {54-63}, address = {San Antonio, TX}, abstract = {

Thin films of lithium nickel oxide were deposited by pulsed laser deposition (PLD) from targets of pressed LiNiO2 powder with layered structure. The composition, structure and surface air sensitivity of these films were analyzed using a variety of techniques, such as nuclear reaction analysis, Rutherford backscattering spectrometry (RBS), x-ray diffraction, infrared spectroscopy, and atomic force microscopy. Optical properties were measured using a combination of variable angle spectroscopic ellipsometry and spectroradiometry. Crystalline structure, surface morphology and chemical composition of LixNi1-xO thin films depend strongly on deposition oxygen pressure, temperature as well as substrate target distance. The films produced at temperatures lower than 600 {\textdegree}C spontaneously absorb CO2 and H2O at their surface once they are exposed to the air. The films deposited at 600 {\textdegree}C proved to be stable in air over a long period. Even when deposited at room temperature the PLD films are denser and more stable than sputtered films. RBS determined that the best electrochromic films had the stoichiometric composition Li0.5Ni0.5O when deposited at 60 mTorr O2 pressure. Electrochemical tests show that the films exhibit excellent reversibility in the range 1.0 V to 3.4 V versus lithium and long cyclic life stability in a liquid electrolyte half cell. Electrochemical formatting which is used to develop electrochromism in other films and nickel oxide films is not needed for these stoichiometric films. The optical transmission range is almost 70\% at 550 nm for 120 nm thick films.

}, author = {Shi-Jie Wen and Klaus von Rottkay and Michael D. Rubin} } @conference {11828, title = {Energy Performance Analysis of Prototype Electrochromic Windows}, booktitle = {ASHRAE Transactions}, volume = {103, Part 2}, year = {1996}, month = {07/1997}, pages = {149-156}, address = {Boston, MA}, abstract = {

This paper presents the results of a study investigating the energy performance of three newly developed prototype electrochromic devices. The DOE-2.1E energy simulation program was used to analyze the annual cooling, lighting, and total electric energy use and peak demand as a function of window type and size. We simulated a prototypical commercial office building module located in the cooling-dominated locations of Phoenix, AZ and Miami, FL. Heating energy use was also studied in the heating-dominated location of Madison, WI. Daylight illuminance was used to control electrochromic state-switching. Two types of window systems were analyzed; i.e., the outer pane electrochromic glazing was combined with either a conventional low-E or a spectrally selective inner pane. The properties of the electrochromic glazings are based on measured data of new prototypes developed as part of a cooperative DOE-industry program.

Our results show the largest difference in annual electric energy performance between the different window types occurs in Phoenix and is about 6.5 kWh/m2 floor area (0.60 kWh/ft2) which can represent a cost of about $.52/m2 ($.05/ft2) using electricity costing $.08/kWh. Much larger differences exist when electrochromic windows are compared to conventional glazings in use today. At large window sizes, such energy savings can be as large as 90 kWh/m2 (8.4 kWh/ft2). Specific electrochromic performance varies with window-to-wall area ratio; i.e., at low ratios, one type electrochromic performs best, while at large ratios, another type performs best. In general, an electrochromic glazing combined with a spectrally selective glazings is better than one combined with a low-E glazing; however, at low-window-to-wall area ratios, this situation reverses slightly. There is almost no difference in peak electric demand for the different electrochromic windows analyzed.

In heating-dominated locations, the electrochromic should be maintained in its bleached state during the heating season to take advantage of beneficial solar heat gain which would reduce the amount of required heating. This also means that the electrochromic window with the largest solar heat gain coefficient is best. The largest heating energy performance difference in Madison for the various window types is 43 MJ/m2 floor area (4.0 kBtu/ft2). This represents a cost of about $.26/m2 floor area ($.024/ft2) using gas costing $0.60/therm ($5.69/GJ, $6.00/MBtu). However, a non-switching electrochromic will not provide desired glare control so that a control strategy that minimizes winter heating use may not be routinely desirable in many buildings.

}, author = {Robert Sullivan and Michael D. Rubin and Stephen E. Selkowitz} } @conference {11831, title = {The Energy Performance of Electrochromic Windows in Heating-Dominated Geographic Locations}, booktitle = {SPIE International Symposium on Optical Materials Technology for Energy Efficiency \& Solar Energy Conversion XV}, year = {1996}, month = {09/1996}, address = {Freiburg, Germany}, abstract = {

This paper presents the results of a study investigating the energy performance of electrochromic windows in heating-dominated geographic locations under a variety of state-switching control strategies. We used the DOE-2.1E energy simulation program to analyze the annual heating, cooling and lighting energy use and performance as a function of glazing type, size, and electrochromic control strategy. We simulated a prototypical commercial office building module located in Madison, Wisconsin. Control strategies analyzed were based on daylight illuminance, incident total solar radiation, and space cooling load. Our results show that overall energy performance is best if the electrochromic is left in its clear or bleached state during the heating season, but controlled during the cooling season using daylight illuminance as a control strategy. Even in such heating dominated locations as Madison, there is still a well-defined cooling season when electrochromic switching will be beneficial. However, having the electrochromic remain in its bleached state during the winter season may result in glare and visual comfort problems for occupants much in the same way as conventional glazings.

}, author = {Robert Sullivan and Eleanor S. Lee and Michael D. Rubin and Stephen E. Selkowitz} } @conference {11832, title = {Energy Performance of Evacuated Glazings in Residential Buildings}, booktitle = {ASHRAE 1996 Summer Meeting, June 22-26, 1996}, volume = {102, Part 2}, year = {1996}, month = {06/1996}, address = {San Antonio, TX}, abstract = {

This paper presents the results of a study investigating the energy performance of evacuated glazings or glazings which maintain a vacuum between two panes of glass. Their performance is measured by comparing results to prototype highly insulated superwindows as well as a more conventional insulating glass unit with a low-E coating and argon gas fill. We used the DOE-2.1E energy analysis simulation program to analyze the annual and hourly heating energy use due to the windows of a prototypical single-story house located in Madison, Wisconsin. Cooling energy performance was also investigated. Our results show that for highly insulating windows, the solar heat gain coefficient is as important as the windows U-factor in determining heating performance for window orientations facing west-south-east. For other orientations in which there is not much direct solar radiation, the windows U-factor primarily governs performance. The vacuum glazings had lower heating requirements than the superwindows for most window orientations. The conventional low-E window outperformed the superwindows for southwest-south-southeast orientations. These performance differences are directly related to the solar heat gain coefficients of the various windows analyzed. The cooling performance of the windows was inversely related to the heating performance. The low solar heat gain coefficients of the superwindows resulted in the best cooling performance. However, we were able to mitigate the cooling differences of the windows by using an interior shading device that reduced the amount of solar gain.

}, author = {Robert Sullivan and Fredric A. Beck and Dariush K. Arasteh and Stephen E. Selkowitz} } @proceedings {11942, title = {Impact of Growth Temperature, Pressure and Strain on the Morphology of GaN Films}, journal = {Materials Research Society Symposium N {\textendash} III-V Nitrides}, volume = {449}, year = {1996}, pages = {227}, abstract = {

GaN films grown on sapphire at different temperatures are investigated. A Volmer-Weber growth mode is observed at temperatures below 1000K that leads to thin films composed of oriented grains with finite size. Their size is temperature dependent and can actively be influenced by strain. Largest grains are observed in compressed films. It is argued that diffusing Ga ad-atoms dominate the observed effects with an activation energy of 2.3 {\textpm} 0.5 eV. Comparably large grain sizes are observed in films grown on off-axes sapphire substrates and on bulk GaN. This assures that the observed size limitation is a consequence of the 3D growth mode and not dependent on the choice of the substrate. In addition, the grain size and the surface roughness of the films depend on the nitrogen partial pressure in the molecular beam epitaxy (MBE) chamber,most likely due to collisions between the reactive species and the background gas molecules. This effect is utilized to grow improved nucleation layers on sapphire.

}, doi = {10.1557/PROC-449-227}, author = {Hiroaki Fujii and Christian F. Kisielowski and Joachim Kr{\"u}ger and Michael S.H. Leung and Ralf Klockenbrink and Michael D. Rubin and Eicke R. Weber}, editor = {Joachim Kr{\"u}ger} } @conference {12092, title = {The National Energy Requirements of Residential Windows in the U.S.: Today and Tomorrow}, booktitle = {ACEEE 1996 Summer Study on Energy Efficiency in Buildings: Profiting from Energy Efficiency}, year = {1996}, month = {08/1996}, address = {Pacific Grove, CA}, abstract = {

This paper describes an end-use analysis of the national energy requirements of U.S. residential window technologies. We estimate that the current U.S. stock of 19 billion square feet of residential windows is responsible for 1.7 quadrillion BTUs (or quads) per year of energy use - 1.3 quads of heating and 0.4 quads of cooling energy - which represents about 2\% of total U.S. energy consumption. We show that national energy use due to windows could be reduced by 25\% by the year 2010 through accelerated adoption of currently available, advanced window technologies such as low-e and solar control low-e coatings, vinyl and wood frames, and superwindows. We evaluate the economics of the technologies regionally, considering both climatic and energy price variations, and find that the technologies would be cost effective for most consumers.

}, url = {http://aceee.org/files/proceedings/1996/data/papers/SS96_Panel10_Paper07.pdf$\#$page=1}, author = {Karl J. Frost and Joseph H. Eto and Dariush K. Arasteh and Mehry Yazdanian} } @techreport {58561, title = {Optical and Electrochromic Properties of Sol-Gel Deposited Doped Tungsten Oxide Films}, year = {1996}, month = {01/1996}, address = {Berkeley}, abstract = {

The goal of this study is to investigate the effects of doping of tungsten oxide on its electrochromic properties. The work is directed toward the development of neutral coloring tungsten oxide materials with properties superior to undoped tungsten oxide. Two basic types of sol-gel formulations were used for experimentation. Type 1 used a WOCl4 precursor. Type 2 used a proprietary (Donnelly) tungsten complex precursor. The Type 2 precursor was used only for comparison to Type 1. Doping experiments were performed using the Type 1 chemistry. The dopants studied were Co, Cr, Nb, Ti, V and Y. The range of dopant was 1-12 mole \%. Improved electrochromic behavior was observed for tungsten oxide films doped with V and Ti.

Analysis of the films included x-ray diffraction, ellipsometry, cyclic voltammetry and spectrophotometry. X-ray diffraction showed that all films heat treated at temperatures below 300{\textdegree}C were amorphous in structure. The refractive indices for undoped films were measured. We found the n, k values of the Type 1 films to be lower than the Type 2 films. The n and k values were n=1.79 and k=2.8x10-3, and n=2.08 and k=3.6x10-3 at 550 nm, for Type 1 and Type 2 films respectively. Both types of tungsten oxide films showed low absorption and high transparency in the visible range. As expected, we found that the film density, and hence the refractive index and extinction coefficient, depended on coating solution chemistry, hydration, and densification procedures. Undoped Type 1 films showed slightly higher lithium diffusion coefficients (DLi), compared to undoped Type 2 films,\ DLi=1.36x 10-9 cm2 s-1 and 1.31 x 10-9 cm2 s-1, respectively.

We also noted that the properties of the films could be reproduced for any coating chemistry and densification scheme. The electrochemical and optical behavior were determined by using an in-situ cuvette cell with a 1M LiCl04 / propylene carbonate electrolyte. Cyclic voltammetric measurements showed that doped Type 1 films exhibited electrochemical reversibility beyond 1200 cycles without change in charge capacity. A slight lowering of charge capacity was noted for the undoped films after cycling. The charge capacity for the V doped film was 16.9 mC/cm2 compared to undoped film, 9.6 mC/cm2. Spectrophotometry showed that doped films tended to exhibit a higher absorbance in their colored state compared to undoped films. Considerable improvement in the lithium diffusivity was noted for all the doped films. The greatest change was a factor of 20x for vanadium doping. Doping appeared to increase the cyclic durability of all the tungsten films out to 1200 cycles. Color changes by doping were noted for several dopants. The doped films with the best overall properties were about 8\% vanadium and titanium tungsten oxide. The optimum concentration lies in the range of 7 to 12 mol\%. The electrochromic color was a neutral brownish-blue for vanadium and grayish-blue for titanium doped tungsten oxide.

}, author = {Nilg{\"u}n {\"O}zer and Carl M Lampert and Michael D. Rubin} } @article {12146, title = {Optical Indices of Electrochromic Tungsten Oxide}, journal = {Thin Solid Films}, volume = {306}, number = {1}, year = {1996}, month = {08/1997}, pages = {10-16}, chapter = {10}, abstract = {

Tungsten trioxide (WO3) is the most widely used material for the active layer of electrochromic devices. Knowledge of the complex refractive index over the range of coloration states is required for device design. Optical constants of WO3 over the whole solar spectrum were determined as a function of injected charge. Films of WO3 were prepared by electron-beam evaporation, then colored in several steps by reduction with lithium (Li) up to 68 mC cm-2 {\textmu}m-1 injected charge. Measurements included variable-angle spectroscopic ellipsometry and spectroscopic transmittance and reflectance at normal incidence. Analysis was complicated by the fact that a transparent-conducting layer of indium tin oxide (ITO) was required to perform lithiation. Optical indices of the glass substrate and ITO transparent conductor were determined separately and then fixed in the model. The indices of WO3 could then be extracted from measurements on the complete structure. A parametric dispersion model corresponding to Gaussian broadening of the oscillators was used to represent the dielectric response of WO3.

}, keywords = {Colored state, Complex refractive index, electrochromic, tungsten oxide}, doi = {10.1016/S0040-6090(97)00254-X}, author = {Klaus von Rottkay and Michael D. Rubin and Shi-Jie Wen} } @article {12147, title = {Optical Indices of Lithiated Electrochromic Oxides}, journal = {Solar Energy Materials and Solar Cells}, volume = {54}, number = {4-Jan}, year = {1996}, month = {07/1998}, pages = {49-57}, chapter = {49}, abstract = {

Optical indices have been determined for thin films of several electrochromic oxide materials. One of the most important materials in electrochromic devices, WO3, was thoroughly characterized for a range of electrochromic states by sequential injection of Li ions. Another promising material, Li0.5Ni0.5O, was also studied in detail. Less detailed results are presented for three other common lithium-intercalating electrochromic electrode materials: V2O5, LiCoO2, and CeO2-TiO2. The films were grown by sputtering, pulsed laser deposition (PLD) and sol-gel techniques. Measurements were made using a combination of variable-angle spectroscopic ellipsometry and spectroradiometry. The optical constants were then extracted using physical and spectral models appropriate to each material. Optical indices of the underlying transparent conductors, determined in separate studies, were fixed in the models of this work. The optical models frequently agree well with independent physical measurements of film structure, particularly surface roughness by atomic force microscopy. Inhomogeneity due to surface roughness, gradient composition, and phase separation are common in both the transparent conductors and electrochromics, resulting sometimes in particularly complex models for these materials. Complete sets of data are presented over the entire solar spectrum for a range of colored states. This data is suitable for prediction of additional optical properties such as oblique transmittance and design of complete electrochromic devices.

}, doi = {10.1016/S0927-0248(97)00222-5}, author = {Michael D. Rubin and Klaus von Rottkay and Shi-Jie Wen and Nilg{\"u}n {\"O}zer and Jonathan L. Slack} } @conference {12148, title = {Optical Indices of Pyrolitic Tin-Oxide Glass}, booktitle = {Materials Research Society 1996 Spring Meeting}, volume = {426}, year = {1996}, month = {04/1996}, address = {San Francisco, CA}, abstract = {

SnO2:F is a widely used transparent conductor and commercially available in a multilayer structure as Tech glass. Current applications include photovoltaics, electrochromics and displays. Optical design of these and other applications requires knowledge of the optical constants, in some cases, over the whole solar spectrum. Various optical property measurements were performed including variable angle spectroscopic ellipsometry, and spectral transmittance and reflectance measurements. This material is deposited in several steps and has a fairly complex structure. The measured data were fit to models based on this structure to obtain the optical indices. Atomic force microscopy confirmed the optically modeled surface roughness.

}, author = {Klaus von Rottkay and Michael D. Rubin} } @conference {12150, title = {Optical Modeling of a Complete Electrochromic Device}, booktitle = {2nd International Conference on Electrochromics}, year = {1996}, month = {10/1996}, address = {San Diego, CA}, abstract = {

Optical indices have been determined for thin films of all materials needed to model a typical electrochromic device. Two electrochromic materials, tungsten oxide and lithium nickel oxide, are widely used in electrochromic devices. The optical indices of the underlying transparent conductors as well as a polymer electrolyte were also analyzed. The optical data was obtained using a combination of variable-angle spectroscopic ellipsometry and spectroradiometry. The data was then fit to appropriate models of structure and dispersion in order to extract the optical indices of the materials. First, the optical indices of the transparent conductive substrates were obtained and fixed in the model. The best models correspond well to independent physical measurements of film structure, such as atomic-force microscopy and surface profiling. Surface roughness, gradient composition and other types of inhomogeneity are common in both the transparent conductors and electrochromic, resulting in particularly complex models. The polymer has a homogeneous structure, but obtaining optically smooth surfaces was a problem. Complete sets of data were produced over the entire solar spectrum for a range of colored states of the films. Using the data for each layer, a realistic electrochromic device was simulated.

}, author = {Klaus von Rottkay and Michael D. Rubin and John B. Kerr} } @conference {12157, title = {Origin of Strain in GaN Thin Films}, booktitle = {23rd International Conference on the Physics of Semiconductors}, volume = {4}, year = {1996}, pages = {513}, address = {Singapore}, abstract = {

Photoluminescence measurements are used to determine the strain in GaN thin films grown by Molecular Beam Epitaxy. The strain which originates from growth on lattice mismatched substrates and from differences in thermal expansion coefficients is found to be greatly relaxed. Residual strains are shown to depend on the thickness of GaN buffer layers and the III/V flux ration during main layer growth. The results strongly suggest that the residual biaxial strain caused by the post-growth cooling can be modified by the incorporation of point defects during the main layer growth which introduce an additional hydrostatic strain field. The effect allows for strain engineering of GaN crystals.

}, author = {Christian F. Kisielowski and Joachim Kr{\"u}ger and Michael S.H. Leung and Ralf Klockenbrink and Hiroaki Fujii and Tadeusz Suski and Sudhir G. Subramanya and Joel W. Ager III and Michael D. Rubin and Eicke R. Weber}, editor = {Joachim Kr{\"u}ger} } @conference {1819, title = {Solar Heat Gain Coefficient of Complex Fenestrations with a Venetian Blind for Differing Slat Tilt Angles}, booktitle = {ASHRAE Symposium}, volume = {103, Part 1}, year = {1996}, month = {01/1997}, address = {Philadelphia, PA}, abstract = {

Measured bidirectional transmittances and reflectances of a buff-colored venetian blind together with a layer calculation scheme developed in previous publications are utilized to produce directional-hemispherical properties for the venetian blind layer and solar heat gain coefficients for the blind in combination with clear double glazing. Results are presented for three blind slat tilt angles and for the blind mounted either interior to the double glazing or between the glass panes. Implications of the results for solar heat gain calculations are discussed in the context of sun positions for St. Louis, MO.

}, author = {Joseph H. Klems and Jeffrey L. Warner} } @conference {1817, title = {Sol-Gel Deposited Electrochromic Films for Electrochromic Smart Window Glass}, booktitle = {International Symposium on Glass Problems, International Commission on Glass}, year = {1996}, month = {09/1996}, address = {Istanbul, Turkey}, abstract = {

Electrochrornic windows offer the ability to dynamically change the transmittance of a glazing. With the appropriate sensor and controls, this smart window can be used for energy regulation and glare control for a variety of glazing applications. The most promising are building and automotive applications. This work covers the use of sol-gel deposition processes to make active films for these windows. The sol-gel process offers a low-capital investment for the deposition of these active films. Sol-gel serves as an alternative to more expensive vacuum deposition processes. The sol-gel process utilizes solution coating followed by a hydrolysis and condensation. In this investigation we report on tungsten oxide and nickel oxide films made by the sol-gel process for electrochromic windows. The properties of the sol-gel films compare favorably to those of films made by other techniques. A typical laminated electrochromic window consists of two glass sheets coated with transparent conductors, which are coated with the active films. The two sheets are laminated together with an ionically conductive polymer. The range of visible transmission modulation of the tungsten oxide was 60\% and for the nickel oxide was 20\%. We used the device configuration of glass/SnO2:F/WO3/polymer/LizNiOxHy/SnO2:F to test the films. The nickel oxide layer had a low level of lithiation and possibly contained a small amount of water. Lithiated oxymethylene-linked poly(ethylene oxide) was used as the laminating polymer. Commercially available Sn02:F/glass (LOF-Tec glass) was used as the transparent conducting glass. We found reasonable device switching characteristics which could be used for devices.

}, author = {Nilg{\"u}n {\"O}zer and Carl M Lampert and Michael D. Rubin} } @article {1849, title = {Strain Related Phenomena in GaN Thin Films}, journal = {Physical Review B}, volume = {54}, number = {24}, year = {1996}, month = {12/1996}, pages = {17745-17753}, chapter = {17745}, abstract = {

Photoluminescence (PL), Raman spectroscopy, and x-ray diffraction are employed to demonstrate the co-existence of a biaxial and a hydrostatic strain that can be present in GaN thin films. The biaxial strain originates from growth on lattice-mismatched substrates and from post-growth cooling. An additional hydrostatic strain is shown to be introduced by the presence of point defects. A consistent description of the experimental results is derived within the limits of the linear and isotropic elastic theory using a Poisson ratio nu =0.23+/-0.06 and a bulk modulus B=200+/-20 GPa. These isotropic elastic constants help to judge the validity of published anisotropic elastic constants that vary greatly. Calibration constants for strain-induced shifts of the near-band-edge PL lines with respect to the E2 Raman mode are given for strain-free, biaxially strained, and hydrostatically contracted or expanded thin films. They allow us to extract differences between hydrostatic and biaxial stress components if present. In particular, we determine that a biaxial stress of one GPa would shift the near-band-edge PL lines by 27+/-2 meV and the E2 Raman mode by 4.2+/-0.3 cm-1 by use of the listed isotropic elastic constants. It is expected from the analyses that stoichiometric variations in the GaN thin films together with the design of specific buffer layers can be utilized to strain engineer the material to an extent that greatly exceeds the possibilities known from other semiconductor systems because of the largely different covalent radii of the Ga and the N atom.

}, doi = {10.1103/PhysRevB.54.17745}, author = {Christian F. Kisielowski and Joachim Kr{\"u}ger and Sergei Ruvimov and Tadeusz Suski and Joel W. Ager III and Erin C. Jones and Zuzanna Liliental-Weber and Michael D. Rubin and Eicke R. Weber and Michael D. Bremser and Robert F. Davis}, editor = {Joachim Kr{\"u}ger} } @conference {1922, title = {Transforming the Market for Residential Windows: Design Considerations for DOE{\textquoteright}s Efficient Window Collaborative}, booktitle = {1996 ACEEE Summer Study on Energy Efficiency in Buildings}, year = {1996}, month = {08/1996}, publisher = {ACEEE}, organization = {ACEEE}, address = {Pacific Grove, CA}, abstract = {

Market adoption of recent, commercially available technological advances that improve the energy performance of windows will lead to immediate economic and energy savings benefits to the nation. This paper is a scoping study intended to inform the design of a major DOE initiative to accelerate market adoption of these windows in the residential sector. We describe the structure of the U.S. residential window market and the interests of the various market players. We then briefly review five recent market transformation initiatives. Finally, we summarize our findings in a list of considerations we believe will be important for the DOE{\textquoteright}s initiative to transform the U.S. residential window market.

}, url = {http://aceee.org/files/proceedings/1996/data/papers/SS96_Panel10_Paper05.pdf$\#$page=1}, author = {Joseph H. Eto and Dariush K. Arasteh and Stephen E. Selkowitz} } @conference {1960, title = {Visual Quality Assessment of Electrochromic and Conventional Glazings}, booktitle = {SPIE Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XV}, year = {1996}, month = {09/1996}, address = {Freiburg, Germany}, abstract = {

Variable transmission, switchable electrochromic glazings are compared to conventional static glazings using computer simulations to assess the daylighting quality of a commercial office environment where paper and computer tasks are performed. RADIANCE simulations were made for a west-facing commercial office space under clear and overcast sky conditions. This visualization tool was used to model different glazing types, to com-pute luminance and illuminance levels, and to generate a parametric set of photorealistic im-ages of typical interior views at various times of the day and year. Privacy and visual dis-play terminal (VDT) visibility is explored. Electrochromic glazings result in a more consis-tent glare-free daylit environment compared to their static counterparts. However, if the glazing is controlled to minimize glare or to maintain low interior daylight levels for critical visual tasks (e.g., VDT), occupants may object to the diminished quality of the outdoor view due to its low transmission (Tv=0.08) during those hours. RADIANCE proved to be a very powerful tool to better understand some of the design tradeoffs of this emerging glazing technology. Our ability to draw specific conclusions about the relative value of dif-ferent technologies or control strategies is limited by the lack of agreed upon criteria or standards for lighting quality and visibility.

}, author = {Martin Moeck and Eleanor S. Lee and Michael D. Rubin and Robert Sullivan and Stephen E. Selkowitz} } @conference {11532, title = {Advances in Thermal and Optical Simulations of Fenestration Systems: The Development of WINDOW 5}, booktitle = {Thermal Performance of the Exterior Envelopes of Buildings VI Conference }, year = {1995}, month = {12/1995}, address = {Clearwater Beach, FL}, abstract = {

WINDOW is a personal-computer-based computer program used by manufacturers, researchers, and consumers to evaluate the thermal performance properties (U-factors, solar heat gain and shading coefficients, and visible transmittances) of complete windows and other fenestration systems. While WINDOW is used by thousands of users in the United States and internationally and is at the foundation of the National Fenestration Rating Council{\textquoteright}s U-factor and solar heat gain property procedures, improvements to the program are still necessary for it to meet user needs. Version 5, intended for release in late 1995, is being developed to meet these needs for increased accuracy, a flexible and state-of-the-art user interface, and the capabilities to handle more product types.

WINDOW 5 includes the capabilities to define and model the thermal performance of frames/dividers and their associated edge effects. Currently, such an analysis must be performed outside of WINDOW and requires simplifications to be made to frame profiles or is based on the use of generic frame and edge correlations. WINDOW{\textquoteright}s two-dimensional thermal model is composed of four sections: a graphical input, automatic grid generation, an finite-element analysis (FEA) solution, and the display of results. In the graphical input section, users are able to directly import a computer-aided design (CAD) drawing or a scanned image of a window profile, replicate its exact geometry, and assign material types and boundary conditions. The automatic grid generation is transparent to the user, with the exception of the requirement that complex shapes (i.e., an aluminum extrusion) be broken down into simpler polyshapes. Inclusion of an automatic grid generation makes detailed "true geometry" frame-and-edge heat-transfer analysis accessible to users without extensive knowledge of numerical methods of heat-transfer analysis. After the cross section is meshed it is sent to the FEA engine for solution and the results are returned. A postprocessor allows for the visual display of temperature and heat flux plots. Note that while this two-dimensional heat-transfer tool is being developed specifically for fenestration products, it also can be used to analyze other building envelope components.

WINDOW 5 also will include a built-in version of a national laboratory{\textquoteright}s program that allows the user to estimate the orientation-dependent annual energy impacts of a given window in a typical residence in various U.S. climates. This program is based on regressions to a database of DOE2.1 runs. Future versions will include a similar feature for commercial buildings.

Other technical additions include an improved angular/ spectral model for coated and uncoated glazings, the ability to analyze the optical properties of nonhomogeneous layers, and the ability to model the effects of laminated glazing layers. A door module permits the user to compute the total U-factors of exterior doors based on component U-factors calculated using the two-dimensional FEA module.

}, author = {Elizabeth U. Finlayson and Dariush K. Arasteh and Michael D. Rubin and John Sadlier and Robert Sullivan and Charlie Huizenga and Dragan C. Curcija and Mark Beall} } @inbook {11533, title = {Advances in Window Technology: 1973-1993}, booktitle = {Advances in Solar Energy, An Annual Review of Research and Development}, year = {1995}, pages = {339-382}, abstract = {

Until the 1970s, the thermal performance of windows and other fenestration technologies was rarely of interest to manufacturers, designers, and scientists. Since then, however, a significant research and industry effort has focused on better understanding window thermal and optical behavior, how windows influence building energy patterns, and on the development of advanced products. This chapter explains how fenestration technologies can make a positive impact on building energy flows, what physical phenomena govern window heat and light transfer, what new products have been developed, and what new products are currently the subject of international research efforts.

}, author = {Dariush K. Arasteh} } @conference {11534, title = {Advancing Lighting and Daylighting Simulation: The Transition from Analysis to Design Aid Tools}, booktitle = {International Building Performance Simulation Association Fourth International Conference}, year = {1995}, month = {08/1995}, address = {Madison, WI}, abstract = {

This paper explores three significant software development requirements for making the transition from standalone lighting simulation/analysis tools to simulation-based design aid tools. These requirements include specialized lighting simulation engines, facilitated methods for creating detailed simulatable building descriptions, and automated techniques for providing lighting design guidance. Initial computer implementations meant to address each of these requirements are discussed to further elaborate these requirements and to illustrate work-in-progress toward fulfilling them.

}, author = {Robert J. Hitchcock} } @conference {11605, title = {Calorimetric Measurements of Inward-Flowing Fraction for Complex Glazing and Shading Systems}, booktitle = {ASHRAE Transactions}, volume = {102, Part 1}, year = {1995}, abstract = {

This paper presents a calorimetric measurement of layer-specific inward-flowing fractions of absorbed solar energy for a number of geometric configurations common in fenestrations with shading. The inward-flowing fractions are found to be relatively insensitive to exterior conditions. Results for an interior venetian blind over double glazing agree with thermal model calculations in the literature, and are the first layer-specific verification of these calculations. It is argued that a data base of these inward-flowing fractions for a suitably broad class of geometries will make possible the determination of solar heat gain coefficient from non-calorimetric measurements of solar-optical properties of complex fenestration components, a procedure termed solar-thermal separation.

}, author = {Joseph H. Klems and Guy O. Kelley} } @conference {11620, title = {Chromogenic Switchable Glazing: Towards the Development of the Smart Window}, booktitle = {Proceedings of Window Innovations Conference 95}, year = {1995}, month = {06/1995}, address = {Toronto, Canada}, abstract = {

The science and technology of chromogenic materials for switchable glazings in building applications is discussed. These glazings can be used for dynamic control of solar and visible energy. Currently many researchers and engineers are involved with the development of products in this field. A summary of activities in Japan, Europe, Australia, USA and Canada is made. The activities of the International Energy Agency are included. Both non-electrically activated and electrically activated glazings are discussed. Technologies covered in the first category are photochromics, and thermochromics and thermotropics. A discussion of electrically activated chromogenic glazings includes dispersed liquid crystals, dispersed particles and electrochromics. A selection of device structures and performance characteristics are compared. A discussion of transparent conductors is presented. Technical issues concerning large-area development of smart windows are discussed.

}, author = {Carl M Lampert} } @conference {11634, title = {A Comparison Between Calculated and Measured SHGC For Complex Fenestration Systems}, booktitle = {ASHRAE Transactions}, volume = {102, Part 1}, year = {1995}, month = {02/1996}, address = {Atlanta, GA}, abstract = {

Calorimetric measurements of the dynamic net heat flow through a complex fenestration system consisting of a buff venetian blind inside clear double glazing are used to derive the direction-dependent beam SHGC of the fenestration. These measurements are compared with calculations according to a proposed general method for deriving complex fenestration system SHGCs from bidirectional layer optical properties and generic calorimetric properties. Previously published optical measurements of the same venetian blind and generic inward-flowing fraction measurements are used in the calculation. The authors find satisfactory agreement between the SHGC measurements and the calculation.

Significant dependence on incident angle was found in the measured SHGCs. Profile angle was not found to be a useful variable in characterizing the system performance. The predicted SHGC was found to be inherently dependent on two angles, although only the incident angle variations were observable under the test conditions.

}, author = {Joseph H. Klems and Jeffrey L. Warner and Guy O. Kelley} } @article {2868, title = {The Design and Evaluation of Integrated Envelope and Lighting Control Strategies for Commercial Buildings}, journal = {ASHRAE Transactions}, volume = {101}, year = {1995}, pages = {326-342}, chapter = {326}, abstract = {

This study investigates control strategies for coordinating the variable solar-optical properties of a dynamic building envelope system with a daylight controlled electric lighting system to reduce electricity consumption and increase comfort in the perimeter zone of commercial buildings. Control strategy design can be based on either simple, instantaneous measured data, or on complex, predictive algorithms that estimate the energy consumption for a selected operating state of the dynamic envelope and lighting system. The potential benefits of optimizing the operation of a dynamic envelope and lighting system are (1) significant reductions in electrical energy end-uses {\textendash} lighting, and cooling due to solar and lighting heat gains {\textendash} over that achieved by conventional static envelope and lighting systems, (2) significant reductions in peak demand, and (3) increased occupant visual and thermal comfort. The DOE-2 building energy simulation program was used to model two dynamic envelope and lighting systems, an automated venetian blind and an electrochromic glazing system, and their control strategies under a range of building conditions. The energy performance of simple control strategies are compared to the optimum performance of a theoretical envelope and lighting system to determine the maximum potential benefit of using more complex, predictive control algorithms. Results indicate that (1) predictive control algorithms may significantly increase the energy-efficiency of systems with non-optimal solar-optical properties such as the automated venetian blind, and (2) simpler, non-predictive control strategies may suffice for more advanced envelope systems incorporating spectrally selective, narrow-band electrochromic coatings.

}, author = {Eleanor S. Lee and Stephen E. Selkowitz} } @conference {11761, title = {Edge Conduction in Vacuum Glazing}, booktitle = {Thermal Performance of the Exterior Envelopes of Buildings VI Conference }, year = {1995}, month = {03/1995}, address = {Clearwater Beach, FL}, abstract = {

Vacuum glazing is a form of low-conductance double glazing using an internal vacuum between the two glass sheets to eliminate heat transport by gas conduction and convection. An array of small support pillars separates the sheets; fused solder glass forms the edge seal. Heat transfer through the glazing occurs by radiation across the vacuum gap, conduction through the support pillars, and conduction through the bonded edge seal. Edge conduction is problematic because it affects stresses in the edge region, leading to possible failure of the glazing; in addition, excessive heat transfer because of thermal bridging in the edge region can lower overall window thermal performance and decrease resistance to condensation.

Infrared thermography was used to analyze the thermal performance of prototype vacuum glazings, and, for comparison, atmospheric pressure superwindows. Research focused on mitigating the edge effects of vacuum glazings through the use of insulating trim, recessed edges, and framing materials. Experimentally validated finite-element and finite-difference modeling tools were used for thermal analysis of prototype vacuum glazing units and complete windows. Experimental measurements of edge conduction using infrared imaging were found to be in good agreement with finite-element modeling results for a given set of conditions. Finite-element modeling validates an analytic model developed for edge conduction.

}, author = {Tom M. Simko and Richard E. Collins and Fredric A. Beck and Dariush K. Arasteh} } @article {11790, title = {Electrochemical Lithium Insertion in Sol-gel Deposited LiNbO3 Films}, journal = {Solar Energy Materials and Solar Cells}, volume = {39}, number = {4-Feb}, year = {1995}, note = {

International Meeting of Electrochromism

}, month = {12/1995}, pages = {367-375}, chapter = {367}, abstract = {

Inorganic LiNbO3 ion conducting films were prepared by sol-gel process involving two alkoxides, lithium ethoxide and niobium ethoxide. The films were analyzed by ellipsometry, X-ray diffractometry, scanning electron microscopy and impedance spectroscopy. Impedance spectroscopy indicated that the Li+ conductivity values were in the range of 6-8 x 10-7 S cm-1. The morphology and thickness of these films played an important role in the insertion of lithium ions. Spectrophotometric investigation showed that LiNbO3 films exhibit very weak cathodic coloration from 350 to 900 nm spectral region. The previous termelectrochemical and opticalnext term properties clearly indicate that sol-gel deposited LiNbO3 films can be used as lithium ion conducting layers for electrochromic device application.

}, doi = {10.1016/0927-0248(96)80002-X}, author = {Nilg{\"u}n {\"O}zer and Carl M Lampert} } @conference {11886, title = {Formation of Metal Oxides by Cathodic Arc Deposition}, booktitle = {International Conference on Metallurgical Coatings and Thin Films, April 24-28, 1995}, year = {1995}, month = {04/1995}, address = {San Diego, CA}, abstract = {

Metal oxide thin films are of interest for a number of applications. Cathodic arc deposition, which is an established and industrially applied technique for the formation of nitrides (e.g. TIN), can also be used for metal oxide thin film formation. A cathodic arc plasma source with the desired cathode material is operated in an oxygen atmosphere of appropriate pressure, and metal oxides of various stoichiometric composition can be formed on different substrates. We report here on a series of experiments on metal oxide formation by cathodic arc deposition for different applications. Black copper oxide has been deposited on accelerator components to increase the radiative heat transfer between the parts. Various metal oxides such as tungsten oxide, niobium oxide, nickel oxide and vanadium oxide have been deposited on ITO glass to form electrochromic films for window applications. Tantalum oxide films are of interest for replacing polymer electrolytes. Optical waveguide structures can be formed by refractive index variation using oxide multilayers. We have synthesized multilayers of Al2O3/Y2O3/Al2O3/Si as possible basic structures for passive optoelectronic integrated circuits, and Al2-xErxO3 thin films with a variable Er concentration which is a potential component layer for the production of active optoelectronic integrated devices such as amplifiers or lasers at a wavelength of 1.53 pm. Aluminum and chromium oxide films have been deposited on a number of substrates to impart improved corrosion resistance at high temperature. Titanium sub-oxides which are electrically conductive and corrosion resistant and stable in a number of aggressive environments have been deposited on various substrates. These sub-oxides are of great interest for use in electrochemical cells. Common features of all these depositions are the high deposition rate typical for cathodic arc deposition, the good adhesion of the films due to the high metal ion energy, and the advantage of an environmentally clean method in comparison to wet-chemical oxide formation techniques.

}, keywords = {Cathodic arc deposition, Oxide formation}, url = {http://dx.doi.org/10.1016/0257-8972(95)02508-1}, author = {Simone Anders and Andr{\'e} Anders and Michael D. Rubin and Zhien Wang and Sebastien Raoux and Fanping Kong and Ian G. Brown} } @conference {11894, title = {Gas Filled Panels: An Update on Applications in the Building Thermal Envelope}, booktitle = {BETEC Fall Symposium, Superinsulations and the Building Envelope}, year = {1995}, month = {11/1995}, address = {Washington, DC}, abstract = {

This paper discusses the application of Gas-Filled Panels to the building thermal envelope. Gas-Filled Panels, or GFPs, are thermal insulating devices that retain a high concentration of a low-conductivity gas, at atmospheric pressure, within a multilayer infrared reflective baffle. The thermal performance of the panel depends on the type of gas fill and the baffle configuration. We present computer simulation results showing the improvement in thermal resistance resulting from using an argon-GFP in place of glass fiber batt insulation in wood-frame construction. This report also presents estimates of the quantity and cost of material components needed to manufacture GFPs using current prototype designs.

}, author = {Brent T. Griffith and Dariush K. Arasteh and Daniel Turler} } @article {11964, title = {The Influence of Nitrogen Ion Energy on the Quality of GaN Films Grown with Molecular Beam Epitaxy}, journal = {Journal of Electronic Materials}, volume = {24}, number = {4}, year = {1995}, month = {04/1995}, pages = {249-255}, chapter = {249}, abstract = {

Since the growth of GaN using molecular beam epitaxy (MBE) occurs under metastable growth conditions, activated nitrogen is required to drive the forward synthesis reaction. In the process of exciting the nitrogen using a plasma or ion-beam source, species with large kinetic energies are generated. Impingement on the growth surface by these species can result in subsurface damage to the growing film, as well as an enhancement of the reverse decomposition reaction rate. In this study, we investigate the effect of the kinetic energy of the impinging nitrogen ions during growth on the resulting optical and structural properties of GaN films. Strong band-edge photoluminescence and cathodoluminescence are found when a kinetic energy of ~10 eV are used, while luminescence is not detectable when the kinetic energies exceeds 18 eV. Also, we find that the use of conductive SiC substrates results in more homogeneous luminescence than the use of insulating sapphire substrates. This is attributed to sample surface charging in the case of sapphire substrates and subsequent variation in the incident ion flux and kinetic energy across the growth surface.This study clearly shows that the quality of GaN films grown by MBE are presently limited by damage from the impingement of high energy species on the growth surface.

}, keywords = {Activated nitrogen, GaN, molecular beam epitaxy (MBE), nitrogen ion energy}, issn = {0361-5235}, doi = {10.1007/BF02659683}, author = {T.C. Fu and Nathan Newman and Erin C. Jones and James S. Chan and Xiaohong Liu and Michael D. Rubin and Nathan W. Cheung and Eicke R. Weber} } @techreport {58588, title = {An Infrared Thermography-Based Window Surface Temperature Database for the Validation of Computer Heat Transfer Models}, year = {1995}, month = {03/1995}, abstract = {

Fenestration heat transfer simulation codes are used in energy performance rating and labeling procedures to model heat transfer through window systems and to calculate window U-values and condensation resistance factors. Experimental measurements of window thermal performance can direct the development of these codes, identify their strengths and weaknesses, set research priorities, and validate finished modeling tools. Infrared (IR) thermography is a measurement technique that is well suited to this task. IR thermography is a relatively fast, non-invasive, non-destructive technique that can resolve thermal performance differences between window components and window systems to a higher degree than a conventional hot box test. Infrared thermography provides spatial resolution of system performance by generating surface temperature maps of windows under controlled and characterized environmental conditions.

This paper summarizes basic theory and techniques for maximizing the accuracy and utility of infrared thermographic temperature measurements of window systems and components in a controlled laboratory setting. The physical setup of a complete infrared thermographic test facility at a major U.S. national research laboratory is described. Temperature measurement issues, and accuracy limits, for quantitative laboratory infrared thermography are discussed. An external reference emitter allows test-specific correction of absolute temperatures measured with an infrared scanner, resulting in {\textquoteright}an absolute measurement accuracy of {\textpm}O.5{\textdegree}C. Quantitative IR thermography is used to form a database of window surface temperature profiles for the validation of finite-element and finite-difference fenestration heat transfer modeling tools. An IR window surface temperature database with complete technical drawings of the windows tested; specification of all test window dimensions, materials, and thermal conductivities; environmental conditions of the tests with associated measurement errors; and two-dimensional surface temperature maps and selected cross sectional temperature profiles in a spreadsheet database format on an electronic media are presented.

}, author = {Fredric A. Beck and Brent T. Griffith and Daniel Turler and Dariush K. Arasteh} } @conference {12004, title = {Issues Associated with the Use of Infrared Thermography for Experimental Testing of Insulated Systems}, booktitle = {Thermal Performance of the Exterior Envelopes of Buildings VI Conference }, year = {1995}, month = {12/1995}, address = {Clearwater Beach, FL}, abstract = {

Infrared scanning radiometers are used to generate temperature maps of building envelope components, including windows and insulation. These temperature maps may assist in evaluating components thermal performance. Although infrared imaging has long been used for field evaluations, controlled laboratory conditions allow improvements in quantitative measurements of surface temperature using reference emitter techniques.

This paper discusses issues associated with the accuracy of using infrared scanning radiometers to generate temperature maps of building envelope components under steady-state, controlled laboratory conditions. Preliminary experimental data are presented for the accuracy and uniformity of response of one commercial infrared scanner. The specified accuracy of this scanner for temperature measurements is 2 {\textdegree}C or 2\% of the total range of values (span) being measured. A technique is described for improving this accuracy using a temperature-controlled external reference emitter. Minimum temperature measurement accuracy with a reference emitter is estimated at {\textpm}0.5 {\textdegree}C for ambient air and background radiation at 21.1 {\textdegree}C and surface temperatures from 0 {\textdegree}C to 21 {\textdegree}C.

Infrared imaging, with a reference emitter technique, is being used to create a database of temperature maps for a range of window systems, varying in physical complexity, material properties, and thermal performance. The database is to be distributed to developers of fenestration heat transfer simulation programs to help validate their models. Representative data are included for two insulated glazing units with different spacer systems.

}, author = {Brent T. Griffith and Fredric A. Beck and Dariush K. Arasteh and Daniel Turler} } @conference {12055, title = {Measured Performance of Selective Glazings}, booktitle = {Thermal Performance of the Exterior Envelopes of Buildings VI Conference }, year = {1995}, month = {12/1995}, address = {Clearwater Beach, FL}, abstract = {

Measurements of the net heat flow through four selective glazings in comparison with clear double glazing under late summer outdoor conditions are presented. The solar heat gain coefficient (SHGC) for each glazing is extracted from the data and shown to be angle-dependent. Good agreement is found between measured properties and calculations with WINDOW 4.1.

}, author = {Joseph H. Klems and Mehry Yazdanian and Guy O. Kelley} } @article {12058, title = {Measurement of Bidirectional Optical Properties of Complex Shading Devices}, journal = {ASHRAE Transactions}, volume = {101, Part 1}, year = {1995}, abstract = {

A new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers such as shades or blinds has been examined in a project jointly sponsored by ASHRAE and DOE. In this method, a scanning radiometer is used to measure the bidirectional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorptances. These properties are in turn combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient.

This paper describes the method of measuring the spatially averaged bidirectional optical properties using an automated, large-sample gonio-radiometer/photometer, termed a Scanning Radiometer. Property measurements are presented for one of the most optically complex systems in common use, a venetian blind. These measurements will form the basis for optical system calculations used to test the method of determining performance.

}, author = {Joseph H. Klems and Jeffrey L. Warner} } @conference {12115, title = {NFRC Efforts to Develop a Residential Fenestration Annual Energy Rating Methodology}, booktitle = {Window Innovations Conference 1995}, year = {1995}, month = {06/1995}, address = {Toronto, Canada}, abstract = {

This paper documents efforts currently being undertaken by the National Fenestration Rating Councils Annual Energy Rating Subcommittee to develop procedures to quantify the energy impacts of fenestration products in typical residential buildings throughout the United States. Parallel paths focus on (1) the development of simplified heating and cooling indices and (2) the development of a more detailed methodology to calculate the cost and energy impacts of specific products in a variety of housing types. These procedures are currently under discussion by NFRCs Technical Committee; future efforts will also address commercial buildings.

}, author = {Brian Crooks and James Larsen and Robert Sullivan and Dariush K. Arasteh and Stephen E. Selkowitz} } @article {12140, title = {Optical and Electrochemical Characteristics of Niobium Oxide Films Prepared by Sol-Gel Process and Magnetron Sputtering: A Comparison}, journal = {Solar Energy Materials and Solar Cells}, volume = {40}, number = {4}, year = {1995}, month = {08/1996}, pages = {285-296}, chapter = {285}, abstract = {

Electrochromic niobia (Nb205) coatings were prepared by the sot-gel spin-coating and d.c. magnetron sputtering techniques. Parameters were investigated for the process fabrication of sol-gel spin coated Nb205 films exhibiting high coloration efficiency comparable with that d.c. magnetron sputtered niobia films. X-ray diffraction studies (XRD) showed that the sot-gel deposited and magnetron sputtered films heat treated at temperatures below 450{\textdegree}C, were amorphous, whereas those heat treated at higher temperatures were slightly crystalline. X-ray photoelectron spectroscopy (XPS) studies showed that the stoichiometry of the films was Nb205. The refractive index and electrochromic coloration were found to depend on the preparation technique. Both films showed low absorption and high transparency in the visible range. We found that the n, k values of the sot-gel deposited films to be lower than for the sputtered films. The n and k values were n = 1.82 and k = 3 {\texttimes} 10-3, and n = 2.28 and k = 4 {\texttimes} 10-3 at 530 urn for sot-gel deposited and sputtered films, respectively. The electrochemical behavior and structural changes were investigated in 1 M LiC104/propylene carbonate solution. Using the electrochemical measurements and X-ray photoelectron spectroscopy, the probable electrode reaction with the lithiation and delithiation is Nb2O5 + x Li+ + x e- <-> LixNb205. Cyclic voltametric (CV) measurements showed that both Nb205 films exhibits electrochemical reversibility beyond 1200 cycles without change in performance. {\textquotedblleft}In situ{\textquotedblright} optical measurement revealed that those films exhibit an electrochromic effect in the spectral range 300 \< λ \< 2100 nm but remain unchanged in the infrared spectral range. The change in visible transmittance was 40\% for 250 nm thick electrodes. Spectroelectrochemical measurements showed that spin coated films were essentially electrochemically equivalent to those prepared by d.c. magnetron sputter deposition.

}, keywords = {D.C. magnetron sputtering, electrochromism, Niobia, optical properties, sol-gel deposition}, doi = {10.1016/0927-0248(95)00147-6}, author = {Nilg{\"u}n {\"O}zer and Carl M Lampert and Michael D. Rubin} } @conference {12141, title = {Optical and Electrochemical Properties of Sol-gel Spin Coated CeO2-TiO2 Films}, booktitle = {SPIE Meeting}, year = {1995}, month = {07/1995}, address = {San Diego, CA}, abstract = {

The optical and electrochemical properties of sol-gel spin coated Ce02-TiO2 (50\% CeO2) films were investigated for electrochrornic applications. The coating solutions were prepared by using mixed organic-inorganic | Ti(OC2H5)4 and Ce(NH4)2 (NO3)6 | precursors. X-ray diffraction studies showed the sol-gel spin-coated films were composed of an amorphous matrix of titanium oxide containing nanocrystallites of cerium oxide. The coating solar transmission value was Ts=0.8 (250 nm thick). The refractive index and the extinction coefficient were derived from transmittance measurements in the UV-VIS-NIR regions. These films had refractive index value of n=2.18 and extinction coefficient value of k=8x10-4 at λ=550 nm. Cyclic voltametric measurements showed reversible electrochemical insertion of lithium ions in a CeO2-TiO2/LiClO4-propylene carbonate electrochemical cell. During cycling the films maintain high optical transmittance. Spectrophotometric and electrochemical investigations performed on CeO2-TiO2 films revealed that these films are suitable as an optically passive counter-electrode in lithium electrochromic devices.

}, keywords = {cerium oxide-titanium oxide, counter electrode, electrochemical properties, electrochromic device, optical properties, sol-gel deposition}, author = {Nilg{\"u}n {\"O}zer and Selmar DeSouza and Carl M Lampert} } @conference {12149, title = {Optical Indices of the Tin-doped Indium Oxide and Tungsten Oxide Electrochromic Coatings}, booktitle = {Material Research Society Symposium }, volume = {403}, year = {1995}, pages = {551-556}, abstract = {

Thin films of tin-doped indium oxide are widely used for transparent conductors. One application of In2O3:Sn (ITO) is transparent contacts for electrochromic electrodes. Optical design of electrochromic devices requires knowledge of the optical constants for each layer from the near ultraviolet and visible to the mid infrared. Determination of the optical constants of the electrochromic layer cannot be made in isolation; a complete device or at least a half-cell including a layer of ITO is required to change the optical state of the electrochromic material. Measurements on ITO were made using variable-angle spectral ellipsometry, and spectral transmittance and reflectance. A series of structural models were fit to this data. The problem is complicated because of inhomogeneity in the films, variability in the manufacturing process, and sensitivity to environmental conditions. The spectral dependency was modeled by a single Lorentz oscillator and a Drude free-electron component. This data was then used as the basis for a model to extract the optical constants for a tungsten oxide electrochromic film.

}, author = {Klaus von Rottkay and Michael D. Rubin and Nilg{\"u}n {\"O}zer} } @article {12195, title = {Preparation and Properties of Spin-Coated Nb2O5 Films by the Sol-Gel Process for Electrochemical Applications}, journal = {Thin Solid Films}, volume = {277}, number = {2-Jan}, year = {1995}, month = {05/1996}, pages = {162-168}, chapter = {162}, abstract = {

The preparation and properties of Nb2O5 coatings made by the sol-gel process were investigated. The films were deposited by spin coating on In2O3:Sn/glass and quartz substrates from a polymeric solutions of niobia derived from niobium ethoxide. The films were characterized by investigation of the stoichiometry, refractive index, optical transmission, electrochemical behavior, and the microstructure. X-ray diffraction studies showed the films to be amorphous for heat treatments below 450 {\textdegree}C. X-ray photoelectron spectroscopy (XPS) measurement revealed the O:Nb atomic stoichiometry to be 5:2. Cyclic voltammetric measurements showed that the Nb2O5/1 M LiClO4-propylene carbonate system exhibits electrochemical reversibility beyond 1200 cycles without change in performance. In situ UV-Vis-NIR spectroelectrochemical measurement revealed that Nb2O5 films exhibit an electrochromic effect in the spectral range 300\<λ\<2100 nm and remain unchanged in the infrared spectral range. The change in visible transmittance was 40\% for a 250 nm thick electrode. XPS spectra indicate that Nb(V) is reduced to a lower valence state Nb(IV) in a colored state with injected Li+. The bronze coloration is due to a simultaneous injection of electrons and Li+ ions into Nb2O5. The sol-gel-deposited\ Nb2O5 films are useful for cathodically coloring electrochromic electrodes in electrochromic devices.

}, keywords = {Electrochemistry, Niobium oxide, optical properties, X-ray photoelectron spectroscopy}, url = {http://dx.doi.org/10.1016/0040-6090(95)08011-2}, author = {Nilg{\"u}n {\"O}zer and Din-Guo Chen and Carl M Lampert} } @conference {12210, title = {Recent Technical Improvements to the WINDOW Computer Program}, booktitle = {Window Innovations 95}, year = {1995}, month = {06/1995}, address = {Toronto, Canada}, abstract = {

The WINDOW series of computer programs has been used since 1985 to model the thermal and optical properties of windows. Each succeeding version of WINDOW has brought its user base new technical capabilities, improvements to the user interface, and greater accuracy. Technical improvements to the current version, which will be released as version 5, are at first being released as stand-alone programs. This paper summarizes the capabilities and algorithms of two of these programs, THERM and LAMINATE. A third stand alone program, RESFEN, which calculates the annual energy effects of specific windows in a typical house throughout the US, will also be incorporated into WINDOW 5; because this program is already in use and documented, it is not discussed in this paper. THERM allows the user to evaluate two dimensional (2-D) heat transfer effects through the solid elements of a window while LAMINATE determines the optical properties of an individual glazing layer with an applied film. Both of these programs are undergoing final development at the time of this writing and will be released as separate programs before they are incorporated into WINDOW 5.

}, author = {Dariush K. Arasteh and Elizabeth U. Finlayson and Michael D. Rubin and John Sadlier} } @conference {12211, title = {Reducing Residential Cooling Requirements Through the Use of Electrochromic Windows}, booktitle = {Thermal Performance of the Exterior Envelopes of Buildings VI Conference Proceedings}, year = {1995}, month = {12/1995}, address = {Clearwater Beach, FL}, abstract = {

This paper presents the results of a study investigating the energy performance of electrochromic windows in a prototypical residential building under a variety of state switching control strategies. We used the DOE-2.1E energy simulation program to analyze the annual cooling energy and peak demand as a function of glazing type, size, and electrochromic control strategy. A single-story ranch-style home located in the cooling-dominated locations of Miami, FL and Phoenix, AZ was simulated. Electrochromic control strategies analyzed were based on incident total solar radiation, space cooling load, and outside air temperature. Our results show that an electrochromic material with a high reflectance in the colored state provides the best performance for all control strategies. On the other hand, electrochromic switching using space cooling load provides the best performance for all the electrochrornic materials. The performance of the incident total solar radiation control strategy varies as a function of the values of solar radiation which trigger the bleached and colored states of the electrochromic (setpoint range); i.e., required cooling decreases as the setpoint range decreases; also, performance differences among electrochromics increases. The setpoint range of outside air temperature control of electrochromics must relate to the ambient weather conditions prevalent in a particular location. If the setpoint range is too large, electrochromic cooling performance is very poor. Electrochromics compare favorably to conventional low-E clear glazings that have high solar heat gain coefficients that are used with overhangs. However, low-E tinted glazings with low solar heat gain coefficients can outperform certain electrochromics. Overhangs should be considered as a design option for electrochromics whose state properties do not change significantly between bleached and colored states.

}, author = {Robert Sullivan and Michael D. Rubin and Stephen E. Selkowitz} } @conference {1815, title = {Sol-Gel Deposited Amorphous Tantalum Oxide and Niobium Oxide Films as Protonic Conductors}, booktitle = {Window Innovations 95 Conference Proceedings}, year = {1995}, month = {06/1995}, address = {Toronto, Canada}, abstract = {

In this work we report on the preparation of tantalum oxide and niobium oxide films by the sol-gel method for use as proton ion conductors in electrochromic devices. Measurement of the proton conductivity was derived from impedence spectroscopy measurements. The proton conductivity for Ta2O5 and NbO5 films was 4.6 x 10-6 Scm-1 and 3.2 x 10-7 Scm-1 respectively. The structural and chemical properties of the films were investigated by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. These films were found to be amorphous and close to the stoichometry of Ta2O5 and NbO5 respectively. In order to estimate the compatibility of these sol-gel deposited layers as ion conductors for EC devices, we investigated tantalum oxide and niobium oxide films deposited on sputtered WO3 films. Charge balance and coloration characteristics were investigated during voltammetric cycling in a pH 2 liquid electrolyte. Spectral transmittance was measured for colored and bleached conditions. The photopic weighted transmittance change and solar weighted transmittance change were Tp=35.2\% - 21.8\% and Ts=75.7\% - 14.2\% for tantala films on tungsten oxide. For niobia on tungsten oxide the values were Tp=85.3\% - 35.2\% and Ts=75.8\% - 28.1\%.

}, author = {Nilg{\"u}n {\"O}zer and Carl M Lampert} } @conference {1816, title = {Sol-Gel Deposited Electrochromic Coatings}, booktitle = {Am. Optical Society, Technical Digest}, volume = {17}, year = {1995}, month = {06/1995}, pages = {344-347}, address = {Tucson, AZ}, abstract = {

Electrochromic devices have increasing application in display devices, switchable minors and smart windows. A variety of vacuum depition technologies have been used to make electrochromic devices. The sol-gel process offers an alternative approach to the synthesis of optical quality and low cost electrochromic device layers. This study summarizes the developments in sol-gel deposited electrochromic films. The sol-gel process involves the formation of oxide networks upon hydrolysis-condensation of alkoxide precursors. In this study we cover the sol-gel deposited oxides of WO3, V2O5, TiO2, Nb2O5 and NiOx.

}, author = {Nilg{\"u}n {\"O}zer and Carl M Lampert} } @conference {1855, title = {Structural and Optical Properties of Sol-Gel Deposited Proton Conducting Ta2O5 Films}, booktitle = {8th International Workshop on Glasses and Ceramics From Gels}, year = {1995}, month = {09/1995}, address = {Faro, Portugal}, abstract = {

Proton conducting tantalum oxide films were deposited by spin coating using a sol-gel process. The coating solutions were prepared using Ta(OC2H5)5 as a precursor. X-ray diffraction studies determined that the sol-gel films, heat treated at temperatures below 400 {\textdegree}C, were amorphous. Films heat treated at higher temperatures were crystalline Ta2O5. The solar transmission values (Ts) of tantala films on glass generally range from 0.8-0.9 depending on thickness. The refractive index and the extinction coefficient were evaluated from transmittance characteristics in the UV-VIS-NIR regions. The refractive index values calculated at λ=550 nm increased from n=1.78 to 1.97 with increasing heat treatment from 150 to 450 {\textdegree}C. The films heat treated at different temperatures showed low absorption with extinction coefficients of less than k=1 x 10-3 in the visible range. Spectrophotometric and impedance spectroscopic investigations performed on Ta2O5 films revealed that these films have protonic conductivity of 3.2 x 10-6 S/cm. The films are suitable for proton conducting layers in electrochromic (EC) devices.

}, keywords = {electrochromic devices, optical proterties, proton conductor, tantalum oxide}, author = {Nilg{\"u}n {\"O}zer and Carl M Lampert} } @article {1872, title = {Surface Temperatures of Insulated Glazing Units: Infrared Thermography Laboratory Measurements}, journal = {ASHRAE Transactions}, volume = {102}, year = {1995}, month = {12/1995}, abstract = {

Data are presented for the distribution of surface temperatures on the warm-side surface of seven different insulated glazing units. Surface temperatures are measured using infrared thermography and an external referencing technique. This technique allows detailed mapping of surface temperatures that is non-intrusive. The glazings were placed between warm and cold environmental chambers that were operated at conditions corresponding to standard design conditions for winter heating. The temperatures conditions are 21.1 {\textdegree}C (70 {\textdegree}F) and -17.8 {\textdegree}C (0 {\textdegree}F) on the warm and cold sides, respectively. Film coefficients varied somewhat with average conditions of about 7.6 W/m2 K (1.34 Btu/h ft2 {\textdegree}F) for the warm-side and 28.9 W/m2 K (5.1 Btu/h ft2 {\textdegree}F) for the cold-side. Surface temperature data are plotted for the vertical distribution along the centerline of the IG and for the horizontal distribution along the centerline. This paper is part of larger collaborative effort that studied the same set of glazings.

}, author = {Brent T. Griffith and Daniel Turler and Dariush K. Arasteh} } @conference {1874, title = {Switchable Glazing: Science and Technology of Smart Windows}, booktitle = {Society of Vacuum Coaters 38th Annual Technical Conference }, year = {1995}, abstract = {

Electrically activated switchable glazing and their use as smart windows and other large-area applications are discussed. Electrochromic devices are compared to dispersed liquid crystals and dispersed particle glazing systems. A selection of device structures and performance characteristics are compared. A discussion of transparent conductors is presented. The characteristics of prototype and commercial devices from commercial and university labs in Japan, Europe, Australia, and USA are covered. A discussion of the future of this technology is made including areas of necessary development for the realization of devices in excess of 1 m2.

}, author = {Carl M Lampert} } @article {1900, title = {Thermal Annealing Characteristics of Si and Mg-implanted GaN Thin Films}, journal = {Applied Physics Letters}, volume = {68}, number = {19}, year = {1995}, month = {03/1996}, pages = {2702-2704}, chapter = {2702}, abstract = {

In this letter, we report the results of ion implantation of GaN using 28Si and 23Mg species. Structural and electrical characterizations of the GaN thin films after thermal annealing show that native defects in the GaN films dominate over implant doping effects. The formation energies of the annealing induced defects are estimated to range from 1.4 to 3.6 eV. A 30 keV10^14 cm-2 Mg implant results in the decrease of the free-carrier concentration by three orders of magnitude compared to unimplanted GaN up to an annealing temperature of 690 {\textdegree}C. Furthermore, we have observed the correlation between these annealing-induced defects to both improved optical and electrical properties.

}, keywords = {annealing, crystal doping, defect states, electrical properties, gallium nitrides, ion implantation, magnesium additions, microstructure, silicon additions}, issn = {0003-6951}, doi = {10.1063/1.116314}, author = {James S. Chan and Nathan W. Cheung and Lawrence F. Schloss and Erin C. Jones and William S. Wong and Nathan Newman and Xiaohong Liu and Eicke R. Weber and A. Gassman and Michael D. Rubin} } @conference {1946, title = {Using Infrared Thermography for the Creation of a Window Surface Temperature Database to Validate Computer Heat Transfer Models}, booktitle = {Windows Innovations Conference 95}, year = {1995}, month = {06/1995}, address = {Toronto, Canada}, abstract = {

Infrared thermography is a non-invasive, non-destructive technique for measuring surface temperatures of an object. These surface temperatures can be used to understand the thermal performance of window components and complete window systems. Infrared (IR) thermography has long been used for qualitative field assessment of window thermal performance, and is now being used in the laboratory for quantitative assessments of window thermal performance. As windows become better and better, more refined test methods and/or simulation tools are required to accurately detect performance changes and make comparisons between products. While hot box calorimetery has worked well to characterize the thermal performance of conventional insulating products, differences in the thermal performance of new highly insulating systems are often less than the resolution of conventional hot box calorimeters. Infrared imaging techniques offer the opportunity to resolve small differences in the thermal performance of components of highly insulating window systems that hot box measurements are not able to identify.

Lawrence Berkeley Laboratory (LBL), a U.S. national research laboratory, is currently using infrared thermography to develop a database of measured surface temperature profiles for a number of different fenestration products for use in validating both basic and advanced two- and three-dimensional finite element method (FEM) and finite difference method (FDM) fenestration heat transfer simulation programs. IR surface temperature data, when taken under controlled laboratory conditions, can be used to direct the development of these simulation codes, identify their strengths and weaknesses, set research priorities, and validate finished modeling tools. Simulation of fenestration heat transfer is faster and less expensive than hot box testing of fenestration products, and forms the basis of window energy codes being implemented, developed, or considered in the US, Canada, the Former Soviet Union, Europe, and Australia. The National Fenestration Rating Council (U. S.) has developed a simulation-based standard which is used to rate and label window U-values for a published directory of over 10,000 different window products.

}, author = {Fredric A. Beck and Brent T. Griffith and Daniel Turler and Dariush K. Arasteh} } @article {1984, title = {Working Principle of the Hollow-Anode Plasma Source}, journal = {Plasma Source Science and Technology}, volume = {4}, year = {1995}, month = {11/1995}, pages = {571-575}, chapter = {571}, abstract = {

The hollow-anode discharge is a special form of glow discharge. It is shown that a drastically reduced anode area is responsible for a positive anode voltage drop of 30-40 V and an increased anode sheath thickness. This leads to ignition of a relatively dense plasma in front of the anode hole. Langmuir probe measurements inside a specially designed hollow anode plasma source give an electron density and temperature of ne=109-1011 cm-3 and Te=1-3 eV, respectively (nitrogen, current 100 mA, flow rate 5-50 scc min-1). Driven by a pressure gradient, the {\textquoteright}anode{\textquoteright} plasma is blown through the anode hole and forms a bright plasma jet streaming with supersonic velocity (Mach number 1.2). The plasma-stream can be used, for instance, in plasma-assisted deposition of thin films.

}, doi = {10.1088/0963-0252/4/4/008}, author = {Andr{\'e} Anders and Simone Anders} } @article {11611, title = {Characterization of Sol-Gel Deposited Niobium Pentoxide Films for Electrochromic Devices}, journal = {Solar Energy Materials and Solar Cells}, volume = {36}, number = {4}, year = {1994}, pages = {433-443}, abstract = {

Niobium pentoxide films, fabricated by the sol-gel process, were spin coated onto conductive indium tin oxide (ITO)/glass, and microscope slides. These films were cycled in a 1M LiClO4 propylene carbonate (PC) solution, and exhibited electrochromic behavior upon the electrochemical insertion (reduction) and extraction (oxidation) of lithium. In-situ optical transmittance measurements were investigated in the ultraviolet/visible/near-infrared wavelength regions (250-2100 nm). Niobium pentoxide films showed reversible optical switching from 320 to 870 nm, but were found electrochromically inactive in the infrared region. Surface analysis using X-ray photoelectron spectroscopy (XPS) indicated little difference in the chemistry of Nb2O5 films as deposited and lithiated LixNb2O5 films, as XPS binding energies of Nb and O showed no appreciable shifts. These films were found to be amorphous by X-ray diffraction. Optical transmittance measurements combined with cyclic voltamograms and XPS spectra, revealed that the electrochromic behavior of these films occurs due to the insertion of Li+ cations into niobium pentoxide films. The bronze coloration of the niobium pentoxide films could make them useful as an electrochromic counter electrodesfor electrochromic devices.

}, author = {Nilg{\"u}n {\"O}zer and Timothy Barreto and Temel Buyuklimanl and Carl M Lampert} } @conference {11612, title = {Characterization of Tantalum Oxide Films Prepared by Sol-Gel Process for electrochemical devices}, year = {1994}, abstract = {

Tantalum oxide films were prepared by sol-gel process using tantalum ethoxide Ta(OC2H5)5. The dependence of deposition conditions (i.e. composition of polymeric solutions and spinning rate) on ionic conductivities for tantalum oxide films were studied. The best results achieved for films fabricated by the spin coating technique were from clear polymeric solutions. These films had low packing density ρ=3.2 g/cm3 and good proton conductivity (about 10-6 Ω-1 cm-1). X-ray photoelectron spectroscopy (XPS) was used for studying the compositions of the tantalum oxide films. We report on the use of tantalum oxide films as ion conductors in devices consisting of WO3/Ta2O5/H+ ion storage polymer structure. We found tantalum oxide to have very good properties for proton device applications.

}, author = {Nilg{\"u}n {\"O}zer and Yongxiang He and Carl M Lampert} } @conference {11643, title = {A Comprehensive Approach to Integrated Envelope and Lighting Systems for New Commercial Buildings}, booktitle = {ACEEE 1994 Summer Study on Energy Efficiency in Buildings}, year = {1994}, month = {09/1994}, address = {Pacific Grove, CA}, abstract = {

We define a comprehensive approach to integrated envelope and lighting systems design as one that balances energy efficiency with anequal regard to the resultant environmental quality. By integrating envelope components (glazing, shading, and daylighting), lighting components (fixtures and controls) and building HVAC/ energy management control systems, we create building systems that have the potential to achieve significant decreases in electricity consumption and peak demand while satisfying occupant physiological and psychological concerns.

This paper presents results on the development, implementation, and demonstration of two specific integrated envelope and lighting systems:

  1. A system emphasizing dynamicsenvelope components and responsive electric lighting systems, that offer the potential to achieve energy efficiency goals and a near optimum comfort environment throughout the year by adapting to meteorological conditions and occupant preferences in real time, and
  2. perimeter daylighting systems that increase the depth of daylight penetration from sidelight windows and improves visual comfort with the use of a small inlet aperture.

The energy performance of the systems was estimated using the DOE-2 building energy simulation program. Field tests with reduced scale models were conducted to determine daylighting and thermal performance in real time under actual weather conditions. Demonstrations of these integrated systems are being planned or are in progress in collaboration with utility programs to resolve real-world implementation issues under complex site, building, and cost constraints. Results indicate that integrated systems offer solutions that not only achieve significant peak demand reductions but also realize consistent energy savings with added occupant comfort and satisfaction.

}, author = {Eleanor S. Lee and Stephen E. Selkowitz and Francis M. Rubinstein and Joseph H. Klems and Liliana O. Beltran and Dennis L. DiBartolomeo} } @conference {11710, title = {The Design and Evaluation of Three Advanced Daylighting Systems: Light Shelves, Light Pipes and Skylights}, booktitle = {Solar 94, Golden Opportunities for Solar Prosperity}, year = {1994}, month = {06/1994}, address = {San Jose, CA}, abstract = {

We present results from the design and evaluation of three advanced daylighting systems: a light shelf, a light pipe, and a skylight. These systems use optical films and an optimizedsgeometry to passively intercept and redirect sunlight further into the building. The objectives of these designs are to increase daylighting illuminance levels at distances of 4.6-9.1 m (15-30 ft) from the window, and to improve the uniformity of the daylight distribution and the luminance gradient across the room under variable sun and sky conditions throughout the year. The designs were developed through a series of computer-assisted ray-tracing studies, photometric measurements, and observations using physical scale models. Comprehensive sets of laboratory measurements in combination with analytical routines were then used to simulate daylight performance for any solar position. Results show increased daylight levels and an improved luminance gradient throughout the year - indicating that lighting energy consumption and cooling energy due to lighting can be substantially reduced with improvements to visual comfort. Future development of the designs may further improve the daylighting performance of these systems.

}, author = {Liliana O. Beltran and Eleanor S. Lee and Konstantinos M. Papamichael and Stephen E. Selkowitz} } @conference {11772, title = {Effect of Switching Control Strategies on the Energy Performance of Electrochromic Windows}, booktitle = {SPIE International Symposium on Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIII, April 18-22, 1994}, year = {1994}, month = {04/1994}, address = {Freiburg, Germany}, abstract = {

This paper presents the results of a study investigating the energy performance of electrochromic windows under a variety of state-switching control strategies. We used the DOE-2.1E energy simulation program to analyze the annual cooling, lighting, and total electricity use and peak demand as a function of glazing type, size, and electrochromic control strategy. We simulated a prototypical commercial office building module located in the cooling-dominated location of Blythe, California. Control strategies analyzed were based on daylight illuminance, incident total solar radiation, and space cooling load. Our results show that when a daylighting strategy is used to reduce electric lighting requirements, control algorithms based on daylight illuminance results in the best overall annual energy performance. If daylighting is not an design option, controls based on space cooling load yield the best performance through solar heat gain reduction. The performance of incident total solar radiation control strategies varies as a function of the switching setpoints; for small to moderate window sizes which result in small to moderate solar gains, a large setpoint-range was best since it provides increased illuminance for daylighting without much cooling penalty; for larger window sizes, which provide adequate daylight, a smaller setpoint-range was best to reduce unwanted solar heat gains and the consequential increased cooling requirement. Of particular importance is the fact that reduction in peak electric demand was found to be independent of the type of control strategy used for electrochromic switching. This is because the electrochromics are generally in their most colored state under peak conditions, and the mechanism used for achieving such a state is not important.

}, author = {Robert Sullivan and Eleanor S. Lee and Konstantinos M. Papamichael and Michael D. Rubin and Stephen E. Selkowitz} } @conference {11890, title = {Fundamental Materials-Issues Involved in the Growth of GaN by Molecular Beam Epitaxy}, year = {1994}, abstract = {

Gallium nitride is one of the most promising materials for ultraviolet and blue light-emitting diodes and lasers. Both Molecular Beam Epitaxy (MBE) and Metal-Organic Chemical Vapor Deposition (MOCVD) have recently made strong progress in fabricating high-quality epitaxial GaN thin films. In this paper, we review materials-related issues involved in MBE growth. We show that a strong understanding of the unique meta-stable growth process allows us to correctly predict the optimum conditions for epitaxial GaN growth. The resulting structural, electronic and optical properties of the GaN films are described in detail.

}, author = {Nathan Newman and T.C. Fu and Z. Liu and Zuzanna Liliental-Weber and Michael D. Rubin and James S. Chan and Erin C. Jones and Jennifer T. Ross and Ian M. Tidswell and Kin Man Yu and Nathan W. Cheung and Eicke R. Weber} } @techreport {1447, title = {Glazing Material for Solar and Architectural Applications}, year = {1994}, month = {09/1994}, abstract = {

This report summarizes five collaborative research projects on glazings performed by participants in Subtask C of IEA Solar Heating and Cooling Programme (SHC) Task 10, Materials Research and Testing. The projects include materials characterization, optical and thermal measurements, and durability testing of several types of new glazings. Three studies were completed on electrochromic and dispersed liquid crystals for smart windows, and two were completed for low-E coatings and transparent insulation materials for more conventional window and wall applications. In the area of optical switching materials for smart windows, the group developed more uniform characterization parameters that are useful to determine lifetime and performance of electrochromics. The detailed optical properties of an Asahi (Japan) prototype electrochromic window were measured in several laboratories. A one square meter array of prototype devices was tested outdoors and demonstrated significant cooling savings compared to tinted static glazing. Three dispersed liquid crystal window devices from Taliq (USA) were evaluated. In the off state, these liquid crystal windows scatter light greatly. When a voltage of about 100 V ac is applied, these windows become transparent. Undyed devices reduce total visible light transmittance by only .25 when switched, but this can be increased to .50 with the use of dyed liquid crystals. A wide range of solar-optical and emittance measurements were made on low-E coated glass and plastic. Samples of pyrolytic tin oxide from Ford glass (USA) and multilayer metal-dielectric coatings from Interpane (Germany) and Southwall (USA) were evaluated. In addition to optical characterization, the samples were exposure-tested in Switzerland. The thermal and optical properties of two different types of transparent insulation materials were measured. Samples of the polycarbonate honeycomb (supplied by Arel in Israel) and monolithic aerogel (supplied by Airglass in Sweden) were evaluated. Discrepancies in the round robin thermal measurements for the honeycomb material pointed out some measurement problems due to different equipment and procedures used. Overall, these glazing studies were successful in improving the understanding and use of advanced glazings. Follow-on work on most of these glazings will be continued in the new IEA SHC Task 18, Advanced Glazing Materials.

}, author = {Windows and Daylighting Group}, editor = {Carl M Lampert} } @conference {11987, title = {Integrated Window Systems: An Advanced Energy-Efficient Residential Fenestration Product}, booktitle = {19th National Passive Solar Conference}, year = {1994}, month = {06/1994}, address = {San Jose, CA}, abstract = {

The last several years have produced a wide variety of new window products aimed at reducing the energy impacts associated with residential windows. Improvements have focused on reducing the rate at which heat flows through the total window product by conduction/convection and thermal radiation (quantified by the U-factor) as well as in controlling solar heat gain (measured by the Solar Heat Gain Coefficient (SHGC) or Shading Coefficient (SC).

Significant improvements in window performance have been made with low-E coated glazings, gas fills in multiple pane windows and with changes in spacer and frame materials and designs. These improvements have been changes to existing design concepts. They have pushed the limits of the individual features and revealed weaknesses. The next generation of windows will have to incorporate new materials and ideas, like recessed night insulation, seasonal sun shades and structural window frames, into the design, manufacturing and construction process, to produce an integrated window system that will be an energy and comfort asset.

}, author = {Dariush K. Arasteh and Brent T. Griffith and Paul LaBerge} } @conference {12084, title = {Modeling Windows in DOE 2.1E}, booktitle = {Thermal Performance of the Exterior Envelopes of Buildings V Conference}, year = {1994}, month = {12/1992}, address = {Clearwater Beach, FL}, abstract = {

The most recent version of the DOE-2 building energy simulation program, DOE-2.1E, provides for more detailed modeling of the thermal and optical properties of windows. The window calculations account for the temperature effects on U-value, and update the incident angle correlations for the solar heat gain properties and visible transmittance. Initial studies show up to a 30\% difference in calculating peak solar heat gain between the detailed approach and a constant shading-coefficient approach. The modeling approach is adapted from Lawrence Berkeley Laboratorys WINDOW 4 computer program, which is used in the National Fenestration Rating Council (NFRC) U-value rating procedure 100-91. This gives DOE-2.1E the capability to assess the annual and peak energy performance of windows consistent with the NFRC procedure. The program has an extensive window library and algorithms for simulating switchable glazings. The program also accounts for the influence of framing elements on the heat transfer and solar heat gain through the window.

}, author = {M. Susan Reilly and Frederick C. Winkelmann and Dariush K. Arasteh and William L. Carroll} } @conference {12233, title = {A Review of Electrochromic Window Performance Factors}, booktitle = {SPIE 13. International Symposium on Optical Materials Technology for Energy Efficiency and Solar Energy Conversion}, year = {1994}, month = {04/1994}, address = {Freiburg, Germany}, abstract = {

The performance factors which will influence the market acceptance of electrochromic windows are reviewed. A set of data representing the optical properties of existing and foreseeable electrochromic window devices was generated. The issue of reflective versus absorbing electrochromics was explored. This data was used in the DOE 2.1 building energy model to calculate the expected energy savings compared to conventional glazings. The effects of several different control strategies were tested. Significant energy and peak electric demand benefits were obtained for some electrochromic types. Use of predictive control algorithms to optimize cooling control may result in greater energy savings. Initial economic results considering annual savings, cooling equipment cost savings, and electrochromic window costs are presented. Calculations of thermal and visual comfort show additional benefits from electrochromics but more work is needed to quantify their importance. The design freedom and aesthetic possibilities of these dynamic glazings should provide additional market benefits, but their impact is difficult to assess at this time. Ultimately, a full assessment of the market viability of electrochromics must consider the impacts of all of these issues.

}, author = {Stephen E. Selkowitz and Michael D. Rubin and Eleanor S. Lee and Robert Sullivan} } @conference {1801, title = {Simulating the Energy Performance of Holographic Glazings}, booktitle = {13th SPIE International Symposium on Optical Materials Technology for Energy Efficiency and Solar Energy Conversion}, year = {1994}, month = {04/1994}, address = {Freiburg, Germany}, abstract = {

The light diffraction properties of holographic diffractive structures present an opportunity to improve the daylight performance in side-lit office spaces by redirecting and reflecting sunlight off the ceiling, providing adequate daylight illumination up to 30 ft (9.14 m) from the window wall. Prior studies of prototypical holographic glazings, installed above conventional view windows, have shown increased daylight levels over a deeper perimeter area than clear glass, for selected sun positions. In this study, we report on the simulation of the energy performance of prototypical holographic glazings assuming a commercial office building in the inland Los Angeles climate.

The simulation of the energy performance involved determination of both luminous and thermal performance. Since the optical complexity of holographic glazings prevented the use of conventional algorithms for the simulation of their luminous performance, we used a newly developed method that combines experimentally determined directional workplane illuminance coefficients with computer-based analytical routines to determine a comprehensive set of daylight factors for many sun positions. These daylight factors were then used within the DOE-2.1D energy simulation program to determine hourly daylight and energy performance over the course of an entire year for four window orientations.

Since the prototypical holographic diffractive structures considered in this study were applied on single pane clear glass, we also simulated the performance of hypothetical glazings, assuming the daylight performance of the prototype holographic glazings and the thermal performance of double-pane and low-e glazings. The results of our analyses show that these prototypical holographic glazings did not save significant electric energy or reduce peak electricity demand compared to conventional energy-efficient window systems in inland Los Angeles office buildings, mainly because of their low diffraction efficiency. Finally, we address various design and implementation issues towards potential performance improvement.

}, author = {Konstantinos M. Papamichael and Liliana O. Beltran and Reto A. Furler and Eleanor S. Lee and Stephen E. Selkowitz and Michael D. Rubin} } @article {1837, title = {Spectrally Selective Glazings for Residential Retrofits in Cooling-Dominated Climates}, journal = {ASHRAE Transactions}, volume = {100}, year = {1994}, abstract = {

Spectrally selective glazings can substantially reduce energy consumption and peak demand in residences by significantly reducing solar gains with minimal loss of illumination and view. In cooling-dominated climates, solar gains contribute 24{\textendash}31\% to electricity consumption and 40{\textendash}43\% to peak demand in homes with single pane clear glazing{\textemdash}standard practice for residential construction built before the implementation of building energy efficiency standards. The existing residential housing stock therefore offers a prime opportunity for significant demand-side management (DSM),but the energy and cost savings must be weighed against retrofit first costs in order for the technology to achieve full market penetration. Using DOE-2.1D for numerical simulation of building energy performance, we quantify the energy and peak demand reductions, cost savings, and HVAC capacity reductions using spectrally selective glazings for five cooling-dominated climates in California. The cost-effectiveness of various material and installation retrofit options is discussed. Glazing material improvements for retrofit applications that are needed to achieve a prescribed cost savings are also given.

}, keywords = {deserts, domestic, energy conservation, Glazing, housing, modernising, subtropics, usa, windows}, author = {Eleanor S. Lee and Deborah Hopkins and Michael D. Rubin and Dariush K. Arasteh and Stephen E. Selkowitz} } @techreport {1970, title = {WINDOW 4.1: Program Description}, year = {1994}, abstract = {

WINDOW 4.1 is a publicly available IBM PC compatible computer program developed by the Windows and Daylighting Group at Lawrence Berkeley Laboratory for calculating total window thermal performance indices (i.e. U-values, solar heat gain coefficients, shading coefficients, and visible transmittances). WINDOW 4.1 provides a versatile heat transfer analysis method consistent with the rating procedure developed by the National Fenestration Rating Council (NFRC). The program can be used to design and develop new products, to rate and compare performance characteristics of all types of window products, to assist educators in teaching heat transfer through windows, and to help public officials in developing building energy codes.

WINDOW 4.1 is an update to WINDOW 4.0. The WINDOW 4 series is a major revision to previous versions of WINDOW. We strongly urge all users to read this manual before using the program. Users who need professional assistance with the WINDOW 4.1 program or other window performance simulation issues are encouraged to contact one or more of the NFRC-accredited Simulation Laboratories.

}, author = {Dariush K. Arasteh and Elizabeth U. Finlayson and Charlie Huizenga} } @conference {11610, title = {Characteristics of Laminated Electrochromic Devices Using Polyorganodisulfate Electrodes}, booktitle = {SPIE Proceedings 2017}, year = {1993}, pages = {143}, abstract = {

The use of polyorganodisulfides as optically passive counterelectrodes in a variety of electrochromic devices are discussed. Characteristic data is presented for electrochmmic devices using proton, and lithium coloration ions with polyethylene oxide electrolyte and polydimercaptothiadiazole positive electrodes. Solid state devices consisting of molybdenum doped W03, amorphous polyethylene oxide electrolyte (a-PEO), and a polyorganodisulfide counter-electrode colored rapidly from a pale yellow to a deep blue-green, upon application of 1.2 V d.c. The photopic transmittance changed from 61 to 98, and the solar transmittance from 45 to 5\% during the coloration process. Also, our experiments with polyimidazole are detailed. This family of compounds due to its unique electrical and ion conduction properties allow a single composite ion storage and ion conductor electrode to be made, simplifying the device construction. Devices rnade from this family of compounds color to deep blue-gray upon application of 1.2-1.5 V. Bleaching occurs at -0.4 to -0.5 s. The photopic transmittance changed from 55 to 9\%. and the solar transmittance from 34 to 4\% during coloration. Both coloration and bleaching are quite rapid.

}, author = {Carl M Lampert and Steven J. Visco and Marca M. Doeff and Yan Ping Ma and Yongxiang He and Jean-Christophe Giron} } @conference {11636, title = {Comparison of AIN Films Grown by RF at Magnetron Sputtering and Ion-Assisted Molecular Beam Epitaxy}, booktitle = {Materials Research Society}, volume = {300}, year = {1993}, month = {04/1993}, address = {San Francisco, CA}, abstract = {

Crystalline aluminum nitride (AlN) thin films were formed on various substrates by using RF magnetron sputtering of an A1 target in a nitrogen plasma and also by ion-assisted molecular beam epitaxy (IAMBE). Basal-oriented AlN/(111) Si showed a degradation of crystallinity with increased substrate temperature from 550 to 770 {\textdegree}C, while the crystallinity of AlN/(0001) Al2O3 samples improved from 700 to 850 {\textdegree}C. The optical absorption characteristics of the AlN/(0001) Al2O3 films as grown by both deposition methods revealed a decrease in sub-band gap absorption with increased substrate temperature.

}, author = {James S. Chan and T.C. Fu and Nathan W. Cheung and Jennifer T. Ross and Nathan Newman and Michael D. Rubin} } @techreport {1379, title = {The Energy Performance of Prototype Holographic Glazings}, year = {1993}, month = {02/1993}, abstract = {

We report on the simulation of the energy performance of prototype holographic glazings in commercial office buildings in a California climate. These prototype glazings, installed above conventional side windows, are designed to diffract the transmitted solar radiation and reflect it off the ceiling, providing adequate daylight illumination for typical office tasks up to 10m from the window. In this study, we experimentally determined a comprehensive set of solar-optical properties and characterized the contribution of the prototype holographic glazings to workplane illuminance in a scale model of a typical office space. We then used the scale model measurements to simulate the energy performance of the holographic glazings over the course of an entire year for four window orientations (North, East, South and West) for the inland Los Angeles climate, using the DOE-2.lD building energy analysis computer program. The results of our experimental analyses indicate that these prototype holographic glazings diffract only a small fraction of the incident light. The results of this study indicate that these prototype holographic glazings will not save energy in commercial office buildings. Their performance is very similar to that of clear glass, which, through side windows, cannot efficiently illuminate more than a 4m - 6m depth of a building{\textquoteleft}s perimeter, because the cooling penalties due to solar heat gain are greater than the electric lighting savings due to daylighting.

}, author = {Konstantinos M. Papamichael and Liliana O. Beltran and Reto A. Furler and Eleanor S. Lee and Stephen E. Selkowitz and Michael D. Rubin} } @article {12065, title = {Measurement of the Exterior Convective Film Coefficient for Windows in Low-Rise Buildings}, journal = {ASHRAE Transactions}, volume = {100, Part 1}, year = {1993}, abstract = {

The MoWiTT field facility is used to measure the convective film coefficient over the exterior surface of a window. The MoWiTT-measured data is compared to some commonly-used experimental and theoretical models. The comparison shows that the MoWiTT data disagrees with the previously used models such as the ASHRAE/DOE-2 model. The reasons for these disagreements are discussed. An experimental model, based on the MoWiTT data, is presented to correlate the film coefficient with the difference in temperatures of the exterior glass surface and the ambient, in the natural convection region, and with the site wind speed, in the forced convection region. The wind speed is considered both in windward and leeward hemispheres. The validity of the MoWiTT model for low-rise buildings is then discussed.

}, author = {Mehry Yazdanian and Joseph H. Klems} } @article {12107, title = {A New Method for Predicting the Solar Heat Gain of Complex Fenestration Systems II. Detailed Description of the Matrix Layer Calculation}, journal = {ASHRAE Transactions}, volume = {100}, year = {1993}, abstract = {

A new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers such as shades or blinds has been examined in a project jointly sponsored by ASHRAE and DOE. In this method, a scanning radiometer is used to measure the bi-directional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorptances. These properties are in turn combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient.

A preceding paper outlined the method and provided the physical derivation of the calculation. In this second of a series of related papers the detailed development of the matrix layer calculation is presented.

}, author = {Joseph H. Klems} } @article {12106, title = {A New Method for Predicting the Solar Heat Gain of Complex Fenestration Systems I. Overview and Derivation of the Matrix Layer Calculation}, journal = {ASHRAE Transactions}, volume = {100, Part 1}, year = {1993}, month = {01/1994}, address = {New Orleans LA}, abstract = {

A new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers such as shades or blinds has been examined in a project jointly sponsored by ASHRAE and DOE. In this method, a scanning radiometer is used to measure the bidirectional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorptances. These properties are in turn combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient. In this first in a series of related papers describing the project, the assumptions and limitations of the calculation method are described and the derivation of the matrix calculation technique from the initial integral equations is presented.

In this first in a series of related papers describing the project, the assumptions and limitations of the calculation method are described and the derivation of the matrix calculation technique from the initial integral equations is presented.

}, author = {Joseph H. Klems} } @conference {12128, title = {Office Lighting: A Review of 80 Years of Standards and Recommendations}, booktitle = {1993 IEEE Industry Applications Society Annual Meeting}, year = {1993}, month = {10/1993}, address = {Toronto, Canada}, abstract = {

This paper traces the development of quantitative office lighting standards from its beginnings to the present. It discusses the sources of recommended lighting practice, the nature of the quantitative recommendations, and trends in recommended values on a comparative basis. A critical assessment of contemporary standards is provided within this historical context.

}, author = {Werner K.E. Osterhaus} } @article {12154, title = {Optical Switching Technology for Glazing}, journal = {Thin Solid Films}, volume = {236}, number = {2-Jan}, year = {1993}, month = {12/1993}, pages = {6-13}, chapter = {6}, abstract = {

The technology of optical switching devices for dynamic glazings and other applications is discussed. The status of the state of the industry and its developments is detailed. The technical emphasis will be on the properties of chromogenic materials covering electrochromic, phase-dispersed liquid crystals and dispersed-particle systems. Such technologies can be used for dynamic control of solar energy through building and vehicle glazings. Both visible and solar control can be obtained from these devices. Switching ranges can be from as high as 80\% to 5-10\% transmittance in the visible region. The energy and daylighting benefits of such glazings are discussed. Also, chromogenic glazings can be used for other product applications such as the modulation of reflector surfaces and large electronic information display systems. The science of selected electrochromic devices is covered. Technical issues concerning large-scale chromogenic devices are discussed.

}, doi = {10.1016/0040-6090(93)90633-Z}, author = {Carl M Lampert} } @conference {12156, title = {Optimizing the Effective Conductivity and Cost of Gas-Filled Panel Thermal Insulations}, booktitle = {22nd International Thermal Conductivity Conference}, year = {1993}, month = {11/1993}, address = {Tempe, AZ}, abstract = {

Gas-Filled Panels, or GFPs, are an advanced theimal insulation that employ a low-conductivity, inert gas, at atmospheiic pressure, within a multilayer reflective baffle. The thermal performance of GFPs varies with gas conductivity, overall panel thickness, and baffle construction. Design parameters of baffle constructions that have a strong effect on GFP thermal resistance are (1) cavities per thickness, (2) cavity surface emittance, and (3) conductance of the baffle materials. GFP thermal performances, where the above parameters were varied, were modeled on a spreadsheet by iterative calculation of one-dimensional energy balances. Heat flow meter apparatus measurements of prototype GFP effective conductivities have been made and are compared to results of the calculations. The costs associated with varying baffle constructions are estimated based on the prices of commercial material components. Results are presented in terms of cost per area per unit thermal resistance ($/Area*R-Value) and are usefid for optimizing GFP designs forsair, argon, or krypton gas fills and a desired effective conductivity and thickness.

}, author = {Brent T. Griffith and Daniel Turler and Dariush K. Arasteh} } @article {12175, title = {Phase I Results of the NFRC U-Value Procedure Validation Project}, journal = {ASHRAE Transactions}, volume = {100, Pt. 1}, number = {Part 1}, year = {1993}, month = {08/1993}, abstract = {

The NFRC U-Value Procedure Validation Project was undertaken by a collaborative group of industry, public utility, trade associations, and government researchers in order to validate the testing and calculational methods of the NFRC 100-91: Procedure for Determining Fenestration Product Thermal Properties (Currently Limited to U-Values). This paper summarizes the validation projects goals and test methodology, the results of the data analysis, and the recommendations following completion of Phase I of the project. Simulations performed according to NFRC 100-91 are shown to agree with each other, to within the NFRC tolerance, in 100\% of the cases. Window test results with perpendicular wind performed according to NFRC 100-91 are shown to agree with each other, to within the NFRC tolerance, in 84\% of the cases. Simulations and perpendicular wind window test results are shown to agree with each other, to within the NFRC tolerance, in 80\% of the cases. Testing of skylights was shown to be problematic under the procedure as written at the time. Agreement between tests and simulations will improve as a result of a strong NFRC education and accreditation program.

}, author = {Dariush K. Arasteh and Fredric A. Beck and Nehemiah Stone and William DuPont and R. Christophe Mathis and Michael Koenig} } @article {12159, title = {P-Type Gallium Nitride by Reactive Ion-Beam Molecular Beam Epitaxy with Ion Implantation, Diffusion or Coevaporation of Mg}, journal = {Applied Physics Letters}, volume = {64}, number = {1}, year = {1993}, pages = {64-66}, chapter = {64}, abstract = {

Gallium nitride is one of the most promising materials for ultraviolet and blue light-emitting diodes and lasers. The principal technical problem that limits device applications has been achieving controllable p-type doping. Molecular beam epitaxy assisted by a nitrogen ion beam produced p-type GaN when doped via ion implantation, diffusion, or coevaporation of Mg. Nearly intrinsic p-type material was also produced without intentional doping, exhibiting hole carrier concentrations of 5{\texttimes}1011 cm-3 and hole mobilities of over 400 cm2/V/s at 250 K. This value for the hole mobility is an order of magnitude greater than previously reported.

}, keywords = {carrier density, carrier mobility, crystal doping, diffusion, evaporation, gallium nitrides, ion implantation, magnesium additions, molecular beam epitaxy, p-type conductors}, issn = {0003-6951}, doi = {10.1063/1.110870}, author = {Michael D. Rubin and Nathan Newman and James S. Chan and T.C. Fu and Jennifer T. Ross} } @techreport {1783, title = {Savings from Energy Efficient Windows: Current and Future Savings from New Fenestration Technologies in the Residential Market}, year = {1993}, note = {

A version of this report was presented at the\ 4th Global Warming International Conference. Chicago, IL, April 5-8, 1993.

}, abstract = {

Heating and cooling energy lost through windows in the residential sector (estimated at two-thirds of the energy lost through windows in all sectors) currently accounts for 3 percent (or 2.8 quads) of total US energy use, costing over $26 billion annually in energy bills. Installation of energy-efficient windows is acting to reduce the amount of energy lost per unit window area. Installation of more energy efficient windows since 1970 has resulted in an annual savings of approximately 0.6 quads. If all windows utilized existing cost effective energy conserving technologies, then residential window energy losses would amount to less than 0.8 quads, directly saving $18 billion per year in avoided energy costs. The nationwide installation of windows that are now being developed could actually turn this energy loss into a net energy gain. Considering only natural replacement of windows and new construction, appropriate fenestration policies could help realize this potential by reducing annual residential window energy losses to 2.2 quads by the year 2012, despite a growing housing stock.

}, author = {Karl J. Frost and Dariush K. Arasteh and Joseph H. Eto} } @conference {1800, title = {Simulating the Daylight Performance of Fenestration Systems and Spaces of Arbitrary Complexity: The IDC Method}, booktitle = {3rd International Conference of the International Building Performance Simulation Association, Building Simulation 93}, year = {1993}, address = {Adelaide, Australia}, abstract = {

A new method to simulate the daylight performance of fenestration systems and spaces is presented. This new method, named IDC (Integration of Directional Coefficients), allows the simulation of the daylight performance of fenestration systems and spaces of arbitrary complexity, under any sun, sky and ground conditions. The IDC method is based on the combination of scale model photometry and computer-based simulation. Physical scale models are used to experimentally determine a comprehensive set of directional illuminance coefficients at reference points of interest, which are then used in analytical, computer-based routines, to determine daylight factors or actual daylight illuminance values under any sun, sky and ground conditions.

The main advantage of the IDC method is its applicability to any optically complex environment. Moreover, the computer-based analytical routines are fast enough to allow for hourly simulation of the daylight performance over the course of an entire year. However, the method requires appropriate experimental facilities for the determination of the Directional Coefficients. The IDC method has been implemented and used successfully in inter-validation procedures with various daylight simulation computer programs. Currently, it is used to simulate the daylight performance of fenestration systems that incorporate optically complex components, such as Venetian blinds, optically treated light shelves and light pipes.

}, author = {Konstantinos M. Papamichael and Liliana O. Beltran} } @article {1921, title = {Towards Large-area Photovoltaic Nanocells: Experiences Learned from Smart Window Technology}, journal = {Solar Energy Materials and Solar Cells}, volume = {32}, number = {3}, year = {1993}, month = {03/1994}, pages = {307-321}, chapter = {307}, abstract = {

This investigation covers two technologies which have different applications but have many similar characteristics. One is the nanocell photoelectrochemical solar cell, the other is the electrochromic window. At first it is hard to see what they have in common other then that they both interact with light.

}, doi = {10.1016/0927-0248(94)90266-6}, author = {Carl M Lampert} } @article {1950, title = {A Validation of the WINDOW4/FRAME3 Linear Interpolation Methodology}, journal = {ASHRAE Transactions}, volume = {100, Part 1}, year = {1993}, abstract = {

The validity of a method to reduce the total number of computer simulations which must be run to determine the U-values of a window product line with multiple glazing options is examined. The accuracy and limits of this method, which uses the WINDOW4 and FRAME simulation programs, is evaluated by comparing the edge, frame, and total window U-values calculated on the basis of single point FRAME simulations to those U-values as calculated on the basis of four point FRAME simulations combined with linear interpolation of frame and edge U-values by WINDOW4. The accuracy of this procedure is examined for two frame types, a low thermal conductivity wood-framed casement and a high thermal conductivity aluminum-framed casement, using both aluminum spacers and insulating spacers over a wide range of glazing types. The effect of center-of-glass U-value, overall glazing thickness and spacer type on frame and edge-of-glass U-values is discussed. It is shown that the agreement between total window U-values as calculated by the single point and four point simulation methods is better than 1\% for double and triple-glazed windows with aluminum spacers, better than 1\% for double-glazed windows with insulating spacers, and better than 2\% for triple-glazed windows with insulating spacers.

}, author = {Fredric A. Beck and Dariush K. Arasteh} } @techreport {1968, title = {Window 4.0: Documentation of Calculation Procedures}, year = {1993}, abstract = {

WINDOW 4.0 is a publicly available IBM PC compatible computer program developed by the Building Technologies Group at the Lawrence Berkeley Laboratory for calculating the thermal and optical properties necessary for heat transfer analyses of fenestration products. This report explains the calculation methods used in WINDOW 4.0 and is meant as a tool for those interested in understanding the procedures contained in WINDOW 4.0. All the calculations are discussed in the International System of units (SI).

}, author = {Elizabeth U. Finlayson and Dariush K. Arasteh and Charlie Huizenga and Michael D. Rubin and M. Susan Reilly} } @techreport {1978, title = {Window U-Value Effects on Residential Cooling Load}, year = {1993}, abstract = {

This paper presents the results of a study investigating the effects of window U-value changes on residential cooling loads. We used the DOE-2.1D energy analysis simulation program to analyze the hourly, daily, monthly, and annual cooling loads as a function of window U-value. The performance of a prototypical single-story house was examined in three locations: hot and humid, Miami FL; hot and dry, Phoenix AZ; and a heating-dominated location with a mildly hot and humid summer, Madison WI. Our results show that when comparing windows with identical orientation, size, and shading coefficient, higher U-value windows often yield lower annual cooling loads, but lower U-value windows yield lower peak cooling loads. This occurs because the window with the higher U-value conducts more heat from inside the residence to the outside during morning and evening hours when the outside air temperature is often lower than the inside air temperature; and, a lower U-value window conducts less heat from outside to inside during summer afternoon peak cooling hours. The absolute effects are relatively small when compared to total annual cooling which is typically dominated by window solar heat gain effects, latent loads, and internal loads. The U-value effect on cooling is also small when compared to both the effects of U-value and solar heat gain on heating load. Our modeling assumed that U-value and solar heat gain could be independently controlled. In fact, reducing window conductance to the levels used in this study implies adding a second glazing layer which always reduces solar heat gain, thus reducing annual cooling. Thus, when we compare realistic options, e.g., single pane clear to double pane clear, or single pane tinted to double pane tinted, the double pane unit shows lower annual cooling, as well as lower peak loads.

}, author = {Robert Sullivan and Karl J. Frost and Dariush K. Arasteh and Stephen E. Selkowitz} } @conference {12011, title = {Large Area Glare Sources and Their Effect on Discomfort and Visual Performance at Computer Workstations}, booktitle = {1992 IEEE Industry Applications Society Annual Meeting}, year = {1992}, month = {10/1992}, address = {Houston, TX}, abstract = {

This paper studies the effects of a large area light source of variable but uniform luminance surrounding a video display terminal (VDT) on the perceived glare discomfort and visual performance of computer operators. A set of criteria was established for rating the discomfort from glare as either intolerable, disturbing, noticeable, or imperceptible. Source luminance adjustments by means of a variable transformer to match the subjective glare criteria, as well as ratings of preselected lighting conditions on a visual analog scale with the same criteria, were used to determine comfortable lighting conditions. Results from the experiment indicate that subjects reliably selected a preferred lighting condition at any time when asked to adjust the luminance to produce optimum visual comfort. There was considerable between-subject variation in the range of luminances over which the surround field was neither noticeably too dim nor noticeably too bright. Comfortable luminance ranges also varied with initial presentation luminances immediately preceding the adjustment. Subjects preferred higher luminances following high initial presentation luminances. Performance speed at a difficult letter-counting task suggests that visual performance was slightly impaired by the presence of glare discomfort. Counting errors also occurred slightly more frequently under higher surround source luminances. There was a tendency for subjects to become more susceptible to glare over the course of the experiment.

}, author = {Werner K.E. Osterhaus and Ian L. Bailey} } @techreport {1641, title = {Net Energy Performance Measurements on Two Low-E Windows}, year = {1992}, abstract = {

Experimental studies using the Mobile Window Thermal Test (MoWiTT) Facility were undertaken to compare the performance of low-E windows manufactured with two different technologies, sputter-coated (soft-coat) and an improved pyrolytic chemical vapor deposition (hard-coat). The two technologies produce coatings with different emissivities and solar absorptions. The tests showed that from the standpoint of winter average daily performance, the higher solar transmission of the pyrolytic coatings tends to offset their higher emissivity, making the average performance of windows with the two coatings more similar than one would predict on the basis of either property alone. The tradeoff between the two window types is both orientation and climate dependent. Differences between the two windows were within the small experimental uncertainty of the measurement for all orientations except south, where the pyrolytic coating produced a larger net heat gain. Summer tests in a west-facing orientation showed that both windows produced large solar heat gains if unshaded, and that shading with an interior white venetian blind was not a very effective way of reducing these heat gains.

}, author = {Joseph H. Klems} } @conference {12105, title = {A New Method for Predicting the Solar Heat Gain of Complex Fenestration Systems}, booktitle = {Thermal Performance of the Exterior Envelope of Buildings V Conference Proceedings}, year = {1992}, month = {12/1992}, address = {Clearwater Beach, FL}, abstract = {

A new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers such as shades or blinds has been examined in a project jointly sponsored by ASHRAE and DOE. In this method, a scanning radiometer is used to measure the bi-directional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorptances. These properties are in turn combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient.

The method has been applied to one of the most optically complex systems in common use, a venetian blind in combination with multiple glazings. A comparison between the scanner-based calculation method and direct system calorimetric measurements made on the LBL MoWiTT facility showed good agreement, and is a significant validation of the method accuracy and feasibility.

}, author = {Joseph H. Klems and Jeffrey L. Warner} } @techreport {1724, title = {Photoelectric Control of Daylight-Following Lighting Systems}, year = {1989}, month = {02/1989}, abstract = {

The ability of daylight-following lighting systems to provide a minimum specified light level at the task surface is influenced by 1) the control algorithm used, 2) the spatial response of the ceiling-mounted control photosensor and 3) the location of the photosensor relative to task and window. Best performance was obtained with a closed-loop proportional control system controlled by a photosensor, with a large field of view but shielded from direct light from the window. A minimum specified illuminance level could be maintained at specific points on the task surface regardless of daylight condition or room geometry provided that the system gain was properly calibrated to account for the local luminous environment.

Open-loop proportional control also performed adequately but offered less precise control than closed-loop systems due to the necessity of using a photosensor that was not shielded from direct window light. Integral-reset systems that were tested performed poorly, but performance could be improved slightly by completely shielding the photocell from direct window light.

}, author = {Francis M. Rubinstein and Rudolph R. Verderber and Gregory J. Ward} } @conference {11992, title = {The Integration of Operable Shading Systems and Lighting Controls}, booktitle = {International Daylighting Conference Proceedings}, year = {1986}, month = {11/1986}, address = {Long Beach, CA}, abstract = {

Using daylighting in commercial buildings may significantly reduce electric lighting requirements if appropriatesphotoelectric controls are used to adjust the electric lighting output according to the available daylight. Prior analysis andsresults from monitored buildings and scale-model measurements suggest that the selection, placement, and installation ofsthe control photosensor is a difficult task, even with simple non-operable fenestration systems, since the daylightscontributions from sun, sky, and ground change continuously. The problem becomes even more complex forsfenestration systems that incorporate operable shading devices, because every adjustment changes the systems opticalsproperties. This paper presents results from measurements in a scale model under real skies, designed to bettersunderstand the problem of integrating fenestration and lighting controls. The scale model represented a typical officesspace and was equipped with motorized venetian blinds. Three control photosensors mounted on the ceiling weresconsidered for the operation of the electric lighting system, and two control strategies were considered for the operation ofsthe venetian blinds. Two ground-plane reflectances and two window orientations were examined. Results indicate thatsthe signal from a ceiling-mounted control photosensor shielded from direct light from the window shows the bestscorrelation with daylight work-plane illuminance, regardless of ground plane reflectance or venetian blind slat angle for allsslat angles that do not allow penetration of direct solar radiation. Results also indicate that the control strategies of thesvenetian blinds that were considered for the purposes of this study may result in significantly different slat angles, andsthus different daylighting work-plane illuminances and electric lighting requirements, especially when the ground-planesreflectance is high.

}, author = {Konstantinos M. Papamichael and Francis M. Rubinstein and Stephen E. Selkowitz and Gregory J. Ward} } @techreport {1330, title = {The Effects of Skylight Parameters on Daylighting Energy Savings}, year = {1985}, abstract = {

Skylight parameters that affect lighting, cooling, heating, fan, and total energy use in office buildings are examined using the state-of-the-art building energy analysis computer code, DOE-2.1B. The lighting effects of skylight spatial distribution, skylight area, skylight visible transmission, well factor, illumination setpoint, interior partitions, ceiling height, and glazing characteristics are discussed. This study serves as the foundation for the creation of a DOE-2.1B database and design tools for estimating daylighting energy savings from skylights.

}, author = {Dariush K. Arasteh and Russell Johnson and Stephen E. Selkowitz} } @article {11829, title = {Energy Performance and Savings Potentials with Skylights}, journal = {ASHRAE Transactions}, volume = {91}, number = {1}, year = {1985}, pages = {154-179}, abstract = {

This study systematically explores the energy effects of skylight systems in a prototypical office building module and examines the savings from daylighting. For specific climates, roof/skylight characteristics are identified that minimize total energy or peak electrical demand. Simplified techniques for energy performance calculation are also presented based on a multiple regression analysis of our data base so that one may easily evaluate daylightings effects on total and component energy loads and electrical peaks. This provides additional insights into the influence of skylight parameters on energy consumption and electrical peaks. We use the DOE-2.15 energy analysis program with newly incorporated daylighting algorithms to determine hourly, monthly, and annual impacts of daylighting strategies on electrical lighting consumption, cooling, heating, fan power, peak electrical demands, and total energy use. A database of more than 2000 parametric simulations for 14 U.S. climates has been generated. Parameters varied include skylight-to-roof ratio, shading coefficient, visible transmittance, skylight well light loss, electric lighting power density, roof heat transfer coefficient, and electric lighting control type.

}, author = {Dariush K. Arasteh and Russell Johnson and Stephen E. Selkowitz and Robert Sullivan} } @conference {1810, title = {Skylight Energy Performance and Design Optimization}, booktitle = {Windows in Building Design and Maintanence}, year = {1984}, month = {06/1984}, address = {Gothenburg, Sweden}, abstract = {

Proper skylight utilization can significantly lower energy requirements and peak electrical loads for space conditioning and lighting in commercial buildings. In this study we systematically explore the energy effects of skylight systems in a prototypical officesbuilding and examine the savings from daylighting. We used the DOE-2.1B energy analysis computer program with its newly incorporated daylighting algorithims to generate more than 2000 parametric simulations for seven U.S. climates. The parameters varied include skylight-to-roof ratio, shading coefficient, visible transmittance, skylight well light loss, electric lighting powersdensity, roof heat transfer coefficient, and type of electric lighting control. For specific climates we identify roof/skylight characteristics that minimize total energy or peak electrical load requirements.

}, author = {Dariush K. Arasteh and Russell Johnson and Robert Sullivan} } @article {12177, title = {Photo-Electric Control of Equi-Illumination Lighting Systems}, journal = {Energy and Buildings}, volume = {6}, year = {1983}, pages = {141-150}, abstract = {

A complete analysis of the cost-effectiveness of daylighting strategies should include the impact of daylighting on peak electrical demand as well as on energy consumption. We utilized an hour-by-hour building energy analysis program to study the thermal and daylighting impacts of fenestration on peak demand. Fenestration properties and lighting system characteristics were varied parametrically for office buildings in Madison WI and Lake Charles LA. Peak electrical demand was disaggregated by component and by zone, monthly patterns of peak demand were examined, and impacts of fenestration performance on chiller size were studied. The results suggest that for daylighted office buildings, the peak electrical demand results from a complex trade-off between cooling load due to fenestration parameters, lighting load reductions due to glazing and lighting system characteristics. Lowest peak demands generally occur with small to moderate size apertures. With daylighting, peak electrical demand is reduced by 10 to 20\% for the building configuration studied (37\% perimeter zone, 63\% core zone). This work indicates that solar gain through fenestration must be effectively controlled in order to realize the potential of daylighting to significantly reduce peak electrical demand.

}, author = {Francis M. Rubinstein} }