Use of IEA-SHC Task 21 C Benchmarks to assess performance of lightscape 3.2 in daylight calculations

In this paper, we use the validation test cases initialized within the subtask C, "Daylight design tools", of IEA SHC Task 21, "Daylight in buildings" to assess the accuracy of a commercial lighting software, Lightscape 3.2. We first analyzed the applicability and the limitations of the IEA 21 test cases, and we concluded some directives for validation test cases in order to guaranty its applicability to assess any lighting software. Then we compared the results obtained with Lightscape 3.2 to the IEA 21 benchmarks in order to assess its performance in daylighting analysis and to position it among the other tested softwares. This comparison showed that Lightscape is in most cases within an acceptable range of accuracy compared to the other tested software programs, with a tendency to increase illuminances resulting of faade openings and to decrease illuminances resulting of roof openings. Results also showed that Lightscape has a remarkable limitation to simulate correctly the contribution of external ground to internal lighting.