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Climate Response

Daylighting Software

Sustainability + LEED


Stanford Graduate Housing Studios 3 & 4

By the mid-1980’s, a number of software packages were under development to predict daylighting performance in buildings, in particular illumination levels in daylighted spaces. An evaluation in 1988 demonstrated that none of the software then available was capable of predicting the simplest of real daylighting designs. In the last ten years, computer capabilities have evolved rapidly and we have four major packages widely available in the United States. This paper presents a comparative evaluation from the perspective of building and daylighting design practice. A contemporary building completed in 1993 was used as a base case for evaluation. We presented the results from field measurements, software predictions and physical modeling as a basis for discussing the capabilities of the software packages in architectural design practice. We found the current software packages far more powerful and nuanced in their ability to predict daylight than before. Some can accurately predict quantitative daylight performance under varying sky conditions and produce handsome and accurate visualizations of the space. The programs differ significantly, however, in their ease of use, modeling basis and the emphasis between quantitative predictions and visualization in the output.


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“Comparative Evaluation of Four Daylighting Software Programs,” Proceedings of the 1998 Summer Study on Energy Efficiency in Buildings, ACEEE, 1998, p. 3.325-340.


Illumination levels predicted by four software packages in comparison to actual daylight levels in an actual building.