02449nas a2200157 4500008004100000050001500041245014100056210006900197260003400266520183000300100002402130700001902154700001802173700002502191856007502216 1998 eng d aLBNL-4177200aExperimental Techniques for Measuring Temperature and Velocity Fields to Improve the Use and Validation of Building Heat Transfer Models0 aExperimental Techniques for Measuring Temperature and Velocity F aClearwater Beach, FLc12/19983 a

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.

1 aGriffith, Brent, T.1 aTurler, Daniel1 aGoudey, Howdy1 aArasteh, Dariush, K. uhttps://facades.lbl.gov/publications/experimental-techniques-measuring01829nas a2200169 4500008004100000050001500041245008200056210006900138260003900207520123000246100002401476700002201500700001801522700001901540700002501559856007501584 1998 eng d aLBNL-4135200aRapid field testing of low-emittance coated glazings for product verification0 aRapid field testing of lowemittance coated glazings for product  aClearwater Beach, Floridac12/19983 a

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.

1 aGriffith, Brent, T.1 aKohler, Christian1 aGoudey, Howdy1 aTurler, Daniel1 aArasteh, Dariush, K. uhttps://facades.lbl.gov/publications/rapid-field-testing-low-emittance02461nas a2200145 4500008004100000245012500041210006900166490001600235520189500251100002402146700002402170700001902194700002502213856007702238 1997 eng d00aImproving Computer Simulations of Heat Transfer for Projecting Fenestration products: Using Radiation View-Factor Models0 aImproving Computer Simulations of Heat Transfer for Projecting F0 v104, Part 13 a

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.

1 aGriffith, Brent, T.1 aCurcija, Dragan, C.1 aTurler, Daniel1 aArasteh, Dariush, K. uhttps://facades.lbl.gov/publications/improving-computer-simulations-heat01252nas a2200145 4500008004100000050001400041245008200055210006900137260002800206520072500234100002400959700002500983700001901008856007901027 1995 eng d aLBL-3809300aGas Filled Panels: An Update on Applications in the Building Thermal Envelope0 aGas Filled Panels An Update on Applications in the Building Ther aWashington, DCc11/19953 a

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.

1 aGriffith, Brent, T.1 aArasteh, Dariush, K.1 aTurler, Daniel uhttps://facades.lbl.gov/publications/gas-filled-panels-update-applications02751nas 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-infrared01611nas a2200157 4500008004100000024001100041245009900052210006900151260001200220490000800232520107300240100002401313700001901337700002501356856007201381 1995 eng d aTA-35200aSurface Temperatures of Insulated Glazing Units: Infrared Thermography Laboratory Measurements0 aSurface Temperatures of Insulated Glazing Units Infrared Thermog c12/19950 v1023 a

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 °C (70 °F) and -17.8 °C (0 °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 °F) for the warm-side and 28.9 W/m2 K (5.1 Btu/h ft2 °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.

1 aGriffith, Brent, T.1 aTurler, Daniel1 aArasteh, Dariush, K. uhttps://facades.lbl.gov/publications/surface-temperatures-insulated02870nas 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-creation01675nas a2200145 4500008004100000050001400041245009100055210006900146260002300215520114400238100002401382700001901406700002501425856007901450 1993 eng d aLBL-3613400aOptimizing the Effective Conductivity and Cost of Gas-Filled Panel Thermal Insulations0 aOptimizing the Effective Conductivity and Cost of GasFilled Pane aTempe, AZc11/19933 a

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.

1 aGriffith, Brent, T.1 aTurler, Daniel1 aArasteh, Dariush, K. uhttps://facades.lbl.gov/publications/optimizing-effective-conductivity-and