02188nas a2200169 4500008004100000024001200041245007000053210006900123260002900192490001600221520160700237100002101844700002201865700002501887700002701912856007901939 1996 eng d aUC-160000aEnergy Performance of Evacuated Glazings in Residential Buildings0 aEnergy Performance of Evacuated Glazings in Residential Building aSan Antonio, TXc06/19960 v102, Part 23 a

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.

1 aSullivan, Robert1 aBeck, Fredric, A.1 aArasteh, Dariush, K.1 aSelkowitz, Stephen, E. uhttps://facades.lbl.gov/publications/energy-performance-evacuated-glazings01938nas a2200157 4500008004100000024001100041245003800052210003800090260003400128520145500162100001901617700002501636700002201661700002501683856007201708 1995 eng d aTA-34200aEdge Conduction in Vacuum Glazing0 aEdge Conduction in Vacuum Glazing aClearwater Beach, FLc03/19953 a

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.

1 aSimko, Tom, M.1 aCollins, Richard, E.1 aBeck, Fredric, A.1 aArasteh, Dariush, K. uhttps://facades.lbl.gov/publications/edge-conduction-vacuum-glazing02751nas a2200145 4500008003900000245012300039210006900162260001200231520219600243100002202439700002402461700001902485700002502504856007602529 1995 d00aAn Infrared Thermography-Based Window Surface Temperature Database for the Validation of Computer Heat Transfer Models0 aInfrared ThermographyBased Window Surface Temperature Database f c03/19953 a

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 'an absolute measurement accuracy of ±O.5°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.

1 aBeck, Fredric, A.1 aGriffith, Brent, T.1 aTurler, Daniel1 aArasteh, Dariush, K. uhttps://facades.lbl.gov/publications/infrared-thermography-based-window02245nas a2200157 4500008004100000024001200041245010600053210006900159260003400228520166300262100002401925700002201949700002501971700001901996856007202015 1995 eng d aUC-160000aIssues Associated with the Use of Infrared Thermography for Experimental Testing of Insulated Systems0 aIssues Associated with the Use of Infrared Thermography for Expe aClearwater Beach, FLc12/19953 a

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 °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 ±0.5 °C for ambient air and background radiation at 21.1 °C and surface temperatures from 0 °C to 21 °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.

1 aGriffith, Brent, T.1 aBeck, Fredric, A.1 aArasteh, Dariush, K.1 aTurler, Daniel uhttps://facades.lbl.gov/publications/issues-associated-use-infrared02870nas a2200157 4500008004100000050001400041245013200055210006900187260002900256520225900285100002202544700002402566700001902590700002502609856007802634 1995 eng d aLBL-3697500aUsing Infrared Thermography for the Creation of a Window Surface Temperature Database to Validate Computer Heat Transfer Models0 aUsing Infrared Thermography for the Creation of a Window Surface aToronto, Canadac06/19953 a

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.

1 aBeck, Fredric, A.1 aGriffith, Brent, T.1 aTurler, Daniel1 aArasteh, Dariush, K. uhttps://facades.lbl.gov/publications/using-infrared-thermography-creation01773nas a2200181 4500008004100000245006900041210006800110260001200178490001500190520118600205100002501391700002201416700002001438700002001458700002301478700002001501856007001521 1993 eng d00aPhase I Results of the NFRC U-Value Procedure Validation Project0 aPhase I Results of the NFRC UValue Procedure Validation Project c08/19930 v100, Pt. 13 a

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.

1 aArasteh, Dariush, K.1 aBeck, Fredric, A.1 aStone, Nehemiah1 aDuPont, William1 aMathis, Christophe1 aKoenig, Michael uhttps://facades.lbl.gov/publications/phase-i-results-nfrc-u-value01768nas a2200133 4500008004100000050001400041245007200055210006900127490001600196520130200212100002201514700002501536856007301561 1993 eng d aLBL-3427100aA Validation of the WINDOW4/FRAME3 Linear Interpolation Methodology0 aValidation of the WINDOW4FRAME3 Linear Interpolation Methodology0 v100, Part 13 a

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.

1 aBeck, Fredric, A.1 aArasteh, Dariush, K. uhttps://facades.lbl.gov/publications/validation-window4frame3-linear