Daylight calculations in practice: An investigation of the ability of nine daylight simulation programs to calculate the daylight factor in five typical rooms

The aim of the project was to obtain a better understanding of what daylight calculations show and also to gain knowledge of how the different daylight simulation programs perform compared with each other.
Experience has shown that results for the same room, obtained from two daylight simulation programs can give different results. This can be due to restrictions in the program itself and/or be due to the skills of the persons setting up the models. This is crucial as daylight calculations are used to document that the demands and recommendations to daylight levels outlined by building authorities.

The aim of the project was to obtain a better understanding of what daylight calculations show and also to gain knowledge of how the different daylight simulation programs perform compared with each other. Furthermore the aim was to provide knowledge of how to build up the 3D models that were to be daylight-analysed. It is an overall objective to enhance the quality of consultancy within the field of daylighting with a greater knowledge of the available daylight simulation programs and the accuracy of the simulated.

The programs investigated are: Radiance, Daysim, VELUX Daylight Visualizer, DIAlux, Ecotect, Ecotect/Radiance, IESve, LightCalc and Relux.