Prediction of Daylight Availability in a Large Hall with Multiple Facades Using Computer Simulation and Subjective Perception

The use of daylighting can minimize energy consumption in buildings. However, people's perception to daylight can be varied for a space that has multiple facades in several orientations. Therefore, assessments should be conducted to predict the correlation between daylight availability metrics and subjective perception of the building occupants. In this study, forty bachelor students were asked to assess a large daylit space, namely the West Hall, in Institut Teknologi Bandung, Indonesia, that has side-lighting on four different sides of the facades. Each student drew boundary lines between daylit and non-daylit area in the given space. The area where 75% boundary lines overlap is categorized as fully daylit, while that with only 25% lines overlap is called partially daylit area. The results were compared to contour lines of daylight autonomy (DA), daylight factor (DF), and useful daylight illuminance (UDI) obtained from simulations in Daysim. The percentage of area enclosed with the contour lines of DA of 50% with target illuminance of 300 lx in the spaceis 55%, close to the third quartiles of the daylit areas according to the participants' preference (56%). Therefore, DA300lx, 50% is more suitable, compared to other daylight metrics, for predicting daylight availability, in particular the partially daylit area in the observed space. DF of 2% can be used to predict the minimum daylit area, since the percentage of area enclosed with its contour lineis similar with theminimum daylit area according to the participants.