Subjective survey & simulation analysis of time-based visual comfort in daylit spaces

Based on the fundamental of instantaneous assessment of visual comfort evaluations, the novelty of this research is the idea to go beyond the instantaneous assess approach and to consider the duration time in predicting visual comfort issues, aims to explore the relationship between human discomfort perceptions and glare integral in time. Subjective survey and 6-min time interval glare metric simulations were taken place in four east-facing test rooms in Guangzhou, China. 16 volunteers participated in this survey from July 6th to Sep 3rd, 2017, all participants ranked the visual discomfort condition three times a day in morning/midday/afternoon. The metric calculation method used in this research was validated in the test room in Guangzhou. The results of this survey illustrated that enhanced simplified DGP (eDGPs) is capable to replace full-rendered DGP in predicting time-based visual comfort issues, and eDGPs has the advantage of being able to be rapid calculated in long-term survey or analysis. Moreover, there existed a strong correlation between the duration time above certain visual comfort thresholds with reported time-based visual comfort. The trigger duration time of 0.45 > eDGPs ≥ 0.40 is 12 min that occupant could evaluate the space visual intolerable and the corresponding median duration time is no less than 24 min. Meanwhile, the median duration time of 0.40 > eDGPs ≥ 0.35 is 6 min that a subject could rank the office space visual disturbing. The trigger duration time of 0.35 > eDGPs ≥ 0.30 is 6 min and the median value is 18 min that subject could probably evaluate the room space as glare perceptible.