Validation of Velux Daylight Visualizer 2 against CIE 171: 2006 test cases

Velux Daylight Visualizer 2 is a software tool dedicated to daylighting design and analysis. It is intended to simulate daylight transport in buildings and to aid professionals by predicting and documenting daylight levels and appearance of a space prior to realization of the building design. The critical question is whether Velux Daylight Visualizer 2 produces trustable simulations the user can be confident in. A key point to answer this question is to assess the software capability to simulate the light transport in a physically correct way. In this paper, we assess the accuracy of Velux Daylight Visualizer 2 against CIE 171:2006 test cases. Like many simulation softwares, several settings (tuned by the final user) rule the accuracy of the simulation and impact the rendering time. We propose an iterative workflow aimed at identifying a range of simulation settings which achieve accurate predictions, and calibrating the simulation settings in regards to accuracy and rendering time. This workflow needs less simulations to perform than simulating each test case for each setting, while remaining robust. We illustrate the proposed workflow by identying low, medium, and high values of the settings of Daylight Visualizer 2.