2019 - Daylight Symposium
"Is Daylight Glare Perceived Differently by People from Different Cultures?" by Clotilde Pierson
PhD at UCLouvain
Developing reliable and accurate methods to evaluate visual discomfort remains a crucial step to move towards optimal daylighting design in buildings. To date, over twenty daylight discomfort glare models have been developed. However, none of them can accurately explain the high variability existing between individuals’ discomfort glare perception. It is assumed that some factors influencing discomfort glare perception are still unknown. One of these potential influencing factors is the culture of the observer.
The culture is defined here as the climate and habitat to which a person has been acclimatized, his/her behavior towards this environment, and his/her expectations about it. Discomfort glare models have been developed through experiments involving particular populations. Until now, no study has examined that these models could be used analogously for people having different culture, thus living in different parts of the world. Several observations have been made in the last 20 years, though, suggesting that people from different cultures could have different sensibilities towards lighting, and especially towards discomfort glare.
The main objective of this study is to determine the existence of differences between the discomfort glare perceptions of people from different cultures, i.e. to assess whether culture influences discomfort glare perception from daylight. For this purpose, the same field study was conducted in four countries: Chile, Belgium, Japan, and Switzerland. These countries were chosen because of climate and cultural requirements, and given the local presence of competent teams in daylighting research. The study consisted in collecting a subjective assessment and a measurement of the discomfort glare stimulus at each participant’s office desk.
To maximize the occurrence of discomfort glare from daylight in the surveyed office buildings, the study was only conducted on clear sky days, for desks located next to an east-, west-, or south-oriented window. The subjective assessment of discomfort glare was recorded through glare rating scales and open questions in a questionnaire, which also asked for other information. The measurement of discomfort glare was done via the calculation of five daylight discomfort glare metrics, based on the luminance map of the visual scene generated through High Dynamic Range photography. In total, 802 discomfort glare evaluations were collected from March 2017 until August 2018, of which 234 evaluations (51 from Chile, 48 from Belgium, 70 from Japan, and 65 from Switzerland) could be used for the analyses to look at the influence of culture on discomfort glare perception.
Different statistical methods were used, but no statistically significant influence of culture on discomfort glare perception could be observed. Based on these results, it is therefore assumed that people from different cultures perceive discomfort glare from daylight similarly. Two other factors, the view through the window and the self-assessed glare sensitivity, were, however, found to have a statistically significant influence on discomfort glare perception. Future research should aim at improving discomfort glare models with these two factors, but not with the cultural factor.
Clotilde Pierson is finishing her PhD at UCLouvain in Belgium. She has a background in architecture engineering, and first worked for one year in an architecture office before starting her PhD research. Her research focuses on the influence of culture on the perception of daylight, and more specifically on the perception of discomfort glare from daylight. To determine whether glare metrics can be applied analogously all over the world, she conducted experiments in Chile, in Japan, and in Switzerland. In this talk, Clotilde will be presenting the results of her 4-year PhD research.