Abstract
The existing discomfort glare models are based on research that was conducted exclusively with uniform luminance sources. It is impossible to apply the models to windows of non-uniform luminance. For evaluating discomfort glare from windows, the method selecting glare source on a window plane is necessary. This study was carried outto propose a practical method to choose glare source from anon-uniform window plane. In the experiment, the perception of glare source according to the luminance difference is examined using a simulated windowof non-uniform luminance. The surface of the window is divided into two or three parts, and different luminance is setting on each surface. The observers were asked to decide whether the lower part of the window can be perceived as a glare source or not. The result shows that the lower part is perceived as a glare source when the lower part has over 37% of the luminance of the upper part of the window divided into two parts, and when it has over 51% of the luminance of the upper part of the window divided into three parts. the results may be applicable to select the glare source in awindow.
