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Perception of discomfort glare in relation to the CIE Unified Glare Rating scale (UGR) and the impact of ambient light on both UGR and Subjective Glare Indexes (SGIs)

Ekim Olsson, Zeynep LU orcid ; Govén, Tommy ; Selvander, Madeleine LU ; Laike, Thorbjörn LU and Sjöberg, Klas LU orcid (2026) In Indoor Environments 3(1).
Abstract
The Unified Glare Rating (UGR) method defined by the International Commission on Illumination is practically the only one used for evaluation of discomfort glare in the lighting design process. However, it is unclear if this method aligns with subjective discomfort glare measures using subjective glare indexes (SGIs). We compared calculated UGR values with commonly used subjective discomfort glare scales across five common office lighting systems. In a controlled laboratory setting with three studies, fifty-nine participants evaluated the degree of perceived discomfort from the selected lighting systems. The findings indicate that classical SGIs were not consistent with UGR values and individual factors (age, sex and emotional state) can... (More)
The Unified Glare Rating (UGR) method defined by the International Commission on Illumination is practically the only one used for evaluation of discomfort glare in the lighting design process. However, it is unclear if this method aligns with subjective discomfort glare measures using subjective glare indexes (SGIs). We compared calculated UGR values with commonly used subjective discomfort glare scales across five common office lighting systems. In a controlled laboratory setting with three studies, fifty-nine participants evaluated the degree of perceived discomfort from the selected lighting systems. The findings indicate that classical SGIs were not consistent with UGR values and individual factors (age, sex and emotional state) can influence the discomfort sensitivity. Furthermore, the findings provide new insights into how ambient light levels and viewing direction affect both calculated discomfort glare and perceived discomfort glare. Collectively, these findings deepen the understanding of discomfort glare and underscore the need to refine glare evaluation methods, with direct implications for office lighting design and standards. (Less)
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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Indoor Environments
volume
3
issue
1
article number
100149
pages
14 pages
publisher
Elsevier
DOI
10.1016/j.indenv.2026.100149
language
English
LU publication?
yes
id
8415e2c1-4978-497a-9e0b-af8f276b3ced
date added to LUP
2026-01-15 10:16:36
date last changed
2026-02-13 16:46:59
@article{8415e2c1-4978-497a-9e0b-af8f276b3ced,
  abstract     = {{The Unified Glare Rating (UGR) method defined by the International Commission on Illumination is practically the only one used for evaluation of discomfort glare in the lighting design process. However, it is unclear if this method aligns with subjective discomfort glare measures using subjective glare indexes (SGIs). We compared calculated UGR values with commonly used subjective discomfort glare scales across five common office lighting systems. In a controlled laboratory setting with three studies, fifty-nine participants evaluated the degree of perceived discomfort from the selected lighting systems. The findings indicate that classical SGIs were not consistent with UGR values and individual factors (age, sex and emotional state) can influence the discomfort sensitivity. Furthermore, the findings provide new insights into how ambient light levels and viewing direction affect both calculated discomfort glare and perceived discomfort glare. Collectively, these findings deepen the understanding of discomfort glare and underscore the need to refine glare evaluation methods, with direct implications for office lighting design and standards.}},
  author       = {{Ekim Olsson, Zeynep and Govén, Tommy and Selvander, Madeleine and Laike, Thorbjörn and Sjöberg, Klas}},
  language     = {{eng}},
  number       = {{1}},
  publisher    = {{Elsevier}},
  series       = {{Indoor Environments}},
  title        = {{Perception of discomfort glare in relation to the CIE Unified Glare Rating scale (UGR) and the impact of ambient light on both UGR and Subjective Glare Indexes (SGIs)}},
  url          = {{http://dx.doi.org/10.1016/j.indenv.2026.100149}},
  doi          = {{10.1016/j.indenv.2026.100149}},
  volume       = {{3}},
  year         = {{2026}},
}