Determination of discomfort glare criteria for daylit space in Indonesia

Abstract

The topic of discomfort glare is an important issue in daylit buildings; however, a consensus on the glare indices and their criteria is hard to achieve, since any measured objective values must show a significant correlation with perception of the space occupants. Applicability of the criteria for each glare indices is yet to be determined, considering various demographic and cultural differences and preferences. However, most studies on discomfort glare from daylight were conducted in regions dominated with Caucasian population. This research aims to determine the appropriate criteria for discomfort glare in Indonesia, using high dynamic range (HDR) imaging technique and post-occupancy evaluation. The objectives are to find correlations between various physical variables and glare indices and to obtain the comfort criteria for daylighting glare in Indonesia.Assessment was conducted in the reading hall of the Main Library Building of Institut Teknologi Bandung. Post-occupancy evaluation was conducted with 99 participants. None of the proposed metrics have a high correlation with the mean subjective score; the largest squared correlation coefficients are given by Evalglare-defined mean source luminance (Ls,Evalglare) and daylight glare probability (DGP). The most significant differences between mean values under comfort and discomfort scenes are also given by those two metrics. The following values are suggested as borders between imperceptible and perceptible glare perception: Ls,Evalglare=1331–1347cd/m2, DGP=0.21; between perceptible and disturbing: Ls,Evalglare=1867–1874cd/m2, DGP=0.22; and between disturbing and intolerable: Ls,Evalglare=2760–3121cd/m2, DGP=0.24–0.26.