Effect of externally and internally reflective components on interior daylighting

•Effect of externally and internally reflective components for a room daylighting.•Daylight simulations were run for winter and summer solstices and two sky models.•Clear sky simulations were compared with traditional overcast sky outputs.•Evaluation of real daylight levels in the room under different sky conditions.

Daylighting in a building residential area was simulated for different external ground reflectances and for various internal surfaces and window to wall areas. The simulations were run in software Velux Daylight Visualizer. Variations in internally and externally reflected components were studied for days of summer and winter solstice under clear and overcast sky conditions. These conditions were selected for two extreme cases for maximal and minimal daylight levels in the internal space during the annual evaluation. The purpose of the simulation study is to find differences in the room daylighting for different conditions than the traditional model of the overcast sky conditions and dark ground. It was found that the room illuminance levels for various interior and exterior reflectances can vary significantly for different sky models. This finding points on the importance of the climate based daylight evaluations.