Interactions among Light Source Luminance, Illuminance and Size on Discomfort Glare

Model predicting discomfort glare caused by LED road lights

“…Semantically a score of 5 indeed refers to a transition between acceptable and non-acceptable. In addition, by consensus, discomfort glare is believed not to be a problem in lighting installations if the VCP is 70% or more [22].The corresponding discomfort glare score based on the deBoer rating was slightly above 5, and so admissible. As such, we can conclude that the two methods for measuring discomfort glare show consistent results.…”

“…According to the model of Bullough [19,20,22], the vertical illuminance at the position of the eye produced by the glare source has a significant effect on discomfort glare. With a diffuser in front of the LED glare source, the emitted light is relatively uniform and can be considered as a cosine radiator.…”

“…The model of deBoer [9], for example, was developed for incandescent lamps, which are nowadays rarely used for road lighting, and also the model of Bullough [19,20,22] was not established for LED-based light sources. The model of Schmidt-Clausen [12] was even developed to predict discomfort glare from headlamps of motor vehicles.…”

“…Based on the deBoer rating scale many models for discomfort glare in road lighting have been developed, i.e., by deBoer et al [11], Schmidt-Clausen et al [12] and Bullough [19,20,22].In general, these models predict the sensation of glare G s from a single glare source for various parameters including the luminance of the glare source L s (in cd/m 2 ), the solid angle subtended at the eye by the glare source ω s (in Sr), the luminance of the background L b (in cd/m 2 ), and the deviation of the glare source from the line of sight p, resulting in Eq. (1) [24].…”

“…Its occurrence was usually assessed by asking observers to rate their discomfort sensation [9][10][11][12][13][14][15][16][17][18][19][20][21][22], and these studies proved that participants could easily give a graded response to the presence of a glare source [23]. The most widely adopted scale used to evaluate discomfort glare was established by deBoer and Schreuder.…”