@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} } @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} } @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} } @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} } @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} } @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} }