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ABSTRACT
To verify the accuracy of lighting simulation programs, the International Commission on Illumination (CIE) published technical report CIE 171:2006—Test Cases to Assess the Accuracy of Lighting Computer Programs, which can be applied to validate lighting simulation tools. This article reports the performance of DIALux 4.12 and DIALux evo 4.1 against the analytical test cases of CIE 171:2006. Both programs show very good agreement with the reference values in cases with point source. DIALux 4.12 yields noticeable errors at receiving points with small configuration factors, in cases with area source. Both programs show good agreement with the reference values in cases with diffuse reflection, respect luminous flux conservation, but do not respect variation in relative angular transmission due to varying incidence angles. Inaccuracies are found in daylighting scenes, particularly in the calculation of sky and externally reflected components. It may be of common interest for the CIE to amend the current document and publish a new version with possibly a new series of test cases.
FUNDING
No special funding was received in the preparation of this article. The author declares no conflict of interest with any parties involved in the creation, development, and distribution of both DIALux programs.