Luminance parameter thresholds for user visual comfort under daylight conditions from subjective responses and physiological measurements in a gymnasium

Abstract

In a gymnasium in Harbin, China, a survey was performed under different lighting conditions to determine the factors influencing the user assessment of daylight environments and define visual comfort thresholds for mass sports activities. Nine subjects experienced the simulated visual environment of basketball shooting by observing the backboard from a designated position, and their visual comfort preferences were evaluated through subjective questionnaires and objective physiological measurements. A total of 108 diverse visual environments were recorded using high dynamic range photography to acquire luminance. The questionnaire factor analysis suggested that the user assessments were mainly determined by their emotional state, glare perception, and visual clarity. The physiological baseline state threshold was proposed based on the physiological measurement data; it described the daylight luminance of the subjects when their physiological value under only natural lighting reached their physiological value under electric lighting. The analysis of the luminance and questionnaire data defined user visual comfort thresholds under only natural lighting: an acceptable average luminance threshold of 42 cd/m2 and a comfortable average luminance threshold of 80 cd/m2 in the entire field of view (FOV); an acceptable maximum luminance threshold of 4800 cd/m2 and a comfortable maximum luminance threshold of 6700 cd/m2 in the entire FOV; a recommended average luminance threshold of 100 cd/m2 in the target area; an acceptable luminance ratio threshold of 42 and a comfort luminance ratio threshold of 21 between the average luminance in window area and the entire FOV.