A first approach to discomfort glare in the presence of non-uniform luminance

This study aims to elucidate the difference in glare sensation between uniform and non-uniform glare sources. In the experiment, the degree of discomfort glare is examined using simulated windows of uniform and non-uniform surface luminance. The window plane is divided into two parts, the upper and lower surfaces, and the luminance and solid angle of each surface are set differently. The upper and lower parts are assumed to be the sky and obstacle, respectively. Two conclusions follow from this study. First, the degree of discomfort glare for the uniform window is higher than it is for the non-uniform window, when the luminance of the uniform window is the same as the average luminance of the non-uniform window. Therefore, the discomfort glare sensation of the non-uniform window is different from that of the uniform window. Second, the glare source in the non-uniform window is restricted by luminance and originates from parts ranging from the highest level of luminance down to a level that is 61% of the highest level of luminance. These results may be useful for selecting the glare source in a window with a non-uniform luminance distribution.