Effect of local background luminance on discomfort glare

The objective of this research is to propose a practical method of determining the background luminance in the evaluation of discomfort glare. Two experiments were conducted, a visual sensitivity test and a glare sensitivity test. The results show that the luminance of threshold and the luminance of discomfort glare are mainly determined by the luminance of the immediate background of the source, rather than by the average background luminance, which has previously been suggested by unified glare rating and visual comfort probability method. Consequently, when the background contains areas of differing luminance, the background luminance of a glare source should be determined by the local background luminance affecting the local adaptation.