Discomfort Glare from Several Sources: A Formula for Outdoor Lighting

Abstract

Many models have been developed to predict the discomfort glare generated by one light source in the visual field. Some of them were generalized to predict discomfort glare from several sources, but they were not directly built from multi-source data. In their generalization, they do not consider the potential interactions due to the fact that the light sources are switched on together. In the present work, a psycho-visual experiment was conducted for a better understanding of the glare produced by several sources using a matching task at the Borderline between Comfort and Discomfort (BCD). A formula is proposed to compute the photometric and geometric characteristics of an equivalent source which generates the same level of discomfort glare as several sources switched on together. This formula is the first step towards a multisource model of discomfort glare. The practical implications are discussed.

Predicting discomfort from glare with pedestrian-scale lighting: A comparison of candidate models using four independent datasets

“…This criterion was used to isolate and omit effects related to multiple light sources and the different approaches that may be used. 26…”

Discomfort Glare from a Cyclic Source in Outdoor Lighting Conditions

“…Under an outdoor lighting installation, the sources have a constant spacing: if an observer drives at constant speed along the luminaires, he experiences an apparent cyclic motion of the sources in his visual field. Given that discomfort from glare from several sources is equivalent to a single source producing the same discomfort (Girard et al, 2019), we have focused on the periodic motion of one source. In addition, in a public lighting installation, we know from previous literature that the luminaire closest to the driver provides most of the discomfort (Bennett, 1987;Bullough et al, 2008).…”

Comment on: Predicting discomfort from glare with pedestrian-scale lighting: A comparison of candidate models using four independent datasets, by Abboushi, Fotios and Miller

“…Regarding such a threshold, studies so far have divergent conclusions. [6][7][8] Indeed, the issue starts already with how L max is measured. Imaging luminance measuring devices (ILMD) offer a promising approach, but limitations in resolution can result in underestimation of L max .…”