Unified Glare Rating (UGR) and subjective appraisal of discomfort glare

Abstract

The study investigated the correlation between the subjective glare rating and the Unified Glare Rating (UGR). Experiments and analyses were carried out. The results showed that there was a good correlation between the subjective glare rating and the UGR glare indices, but that the subjective glare ratings were always a few units lower than the UGR glare indices. The reason for the difference between them may be that simply 'adding up' the glare sensation is not an appropriate way to evaluate discomfort glare. Finally, a method is proposed for modification concerning the additivity of discomfort glare.