@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} } @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} } @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 {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} } @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} } @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 {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} } @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} } @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} }