Investigation of illuminance-based metrics in predicting occupants’ visual comfort (case study: Architecture design studios)

Abstract

Daylight and glare metrics are useful to quantify visual performance, minimize visual discomfort, and promote energy savings.This study evaluates the performance and robustness of some dynamic and static daylight and glare metrics by field studies in twenty architectural studios, daylit by different strategies (i.e., skylight, clerestory, side-lit windows). Experimental datasets (measurements and questionnaire surveys) were collected from three universities during different months. The daylight and glare metrics were also calculated by simulation and compared to occupants’ responses and onsite measurement. Based on the results, the metrics are rated based on their consistency with occupants’ perception. Moreover, the acceptable thresholds of metrics, recommended by standards and experts, are investigated. Results show that occupants’ perceptions are correlated to Point-in-Time-Illuminance (EP), Spatial Daylight Autonomy (sDA), and Useful Daylight Illuminance (UDI) respectively, while no significant correlation has been observed between grid-based glare metrics and users’ responses. According to the results, among annual metrics, UDI300-3000/50% ≥ 75% and Annual Sunlight Exposure (ASE1000, 250h ≤ 10%) have better performance in predicting daylight availability and visual discomfort. Consequently, two simple indices (EDSDaylight and ESDGlare) are presented to predict daylight satisfaction and visual discomfort based on architectural parameters to be used in the early design stage.