Determination of the Simplified Daylight Glare Probability (DGPs) Criteria for Daylit Office Spaces in Thailand

Abstract

The increasing trend of employing glazed façades to utilize daylight in the buildings has made it necessary to develop measures to avoid excessive sunlight penetration in such daylit spaces. In Thailand, only a few studies have focused on daylight glare, and therefore, applicable criteria are required to fulfill the local preference. This study aimed to determine daylight glare thresholds on the basis of the occupants’ responses. A post-occupancy evaluation with a simplified daylight glare probability (DGPs) model was performed in eight open-plan office spaces located in Bangkok, Thailand. The occupants participated in a survey including a subjective questionnaire; the results showed that the DGPs model performed effectively for glare prediction, with a preference for a lower level than that found in the current references. Statistical analysis helped mark the threshold values for each glare sensation level: imperceptible–perceptible = 0.22; perceptible–disturbing = 0.24; and disturbing–intolerable = 0.26. The findings of this study can be considered as initial evidence for improving the understanding of local occupants’ perspectives and illumination standards, which currently encourage daylight utilization without any specific glare control strategies.