Discomfort glare from daylight: Influence of transmitted color and the eye's macular pigment

Designing architectural façades that allow sufficient daylight to create visually comfortable and pleasant environments is a challenging aspect of building design. It requires accounting for visual comfort and discomfort glare risks and understanding the factors that influence them. In the last two decades, several prediction models have been developed to quantify discomfort glare by considering almost exclusively the photometric properties and spatial distribution of incoming light. Although these empirical models have been derived to best match one's perception of glare, they fail to account for the significant interindividual variability that exists in glare perception and are furthermore limited in their applicability in certain visual environments. It is evident from the literature that not all the factors influencing discomfort glare perception are known and accounted for in the existing prediction models. Based on the literature review, we have identified two potential factors, namely, the macular pigment density in the retina and the color of daylight, as likely to influence discomfort glare perception. Up to now, their influence on glare induced by daylight has remained unknown.

To address this gap, this thesis aims to determine the influence of macular pigment density and color of the sun disc (altered by colored glazing) on discomfort glare perception in daylit environments. By means of three psychophysical experiments conducted in office-like test rooms along with the ocular examinations of the participants, we determined the influence of macular pigment and color of daylight on the perception of discomfort glare for young and healthy individuals. Three experiments were conducted, one with blue electrochromic glazing, one with color-neutral glazing, and the third with red, blue, green, and color-neutral glazing. Each experiment followed a similar protocol of exposing every participant to four daylight glare scenarios and recording their responses to questionnaires. The four daylight scenarios differed either in color or in the transmittance of the glazing through which the sun was visible as the primary glare source. The remaining windows were set in a way to keep the overall color rendering in the space as neutral as possible.

The results show that macular pigment density does not influence discomfort glare perception from the sun disc filtered by color-neutral glazing in the near-peripheral field of view. However, when exposed to the sun disc filtered by saturated blue-colored glazing also in the near-peripheral field, participants with higher macular pigment density were better able to tolerate the glare, indicating a significant influence of macular pigment in this case.

In regards to the influence of color, results show that the perceived color of the sun disc (as filtered by colored glazing) has a strong influence on participants' perception of glare. Direct sunlight filtered through four types of colored glazing of a similar