DOES COLOR OF GLAZING CHANGE OUR PERCEPTION OF GLARE FROM DAYLIGHT?

Windows in workplace environment are desirable for their several proven physiological, psychological and economic benefits. Daylight from windows is also responsible for glare which can cause occupants to close the blinds. Glazing properties of the windows play a key role in defining the quality and quantity of the transmitted daylight in a space and therefore controlling glare. With the current trend of colored glazing such blue electrochromic glazing, colored PV panels, dye-sensitized solar cell glazing, it is essential to know the effect of altered spectrum of daylight on glare perception which has not been studied yet. Towards this end, we determine for the first time whether the spectrum of daylight glare source (i.e. the sun) altered by colored glazing influences human perception of glare in workplace scenarios following a psychophysical procedure. We designed a controlled lab study with 50 participants experiencing glare under red, blue, green and grey (color-neutral) colored glazing in an office-like test room with sun behind the glazing as the only glare source. The study was designed as a combination of within-between design where color of glazing was changing within participants and transmittance of glazing was changing between participants. Each participant was exposed to all four colored glazings with similar visible light transmittances resulting in exposure to similar levels of glare metrics values and the color of glazing was the only variable within the tested scenes. Two levels of glazing transmittances (τv = 0.3%, 3%) were tested under all four colors with 25 participants under each transmittance. Results indicate that there is an influence of color on participants perception of glare independent of transmittance. We found that the participants experienced statistically much higher levels of glare under red glazing followed by blue glazing and least discomfort under grey and green glazing. These results indicate a clear effect of color or glare source spectrum on glare perception and calls for an update to glare metrics to include this effect to account for the differences in perception of glare. Results further indicate the inapplicability of photopic luminosity function V () in quantifying luminance for brightly lit saturated colored glare sources.