Investigation the Performance of Glare Indices in Iran's Hot and Dry Climate

Subject Areas : Architecture and urbanism

mahbubeh pourahmadi ¹ (PhD Candidate, Architecture, Iran University of Science and Technology, Tehran, Iran)
mohammadali khanmohamadi ² (Associate Professor, Architecture, Iran University of Science and Technology, Tehran, Iran* (Corresponding Author))
farhang mozafar ³ (Associate Professor, Architecture, Iran University of Science and Technology, Tehran, Iran.)

Received: 2018-03-28 Accepted : 2018-10-03 Published : 2021-03-21

Keywords: Glare Indices, visual comfort, Discomfort Glare, Daylighting,

Abstract :

Background and Objective: Discomfort glare is a common issue in modern building. Glare not only has negative effect on the comfort of occupant but also increases energy consumption in the building. However, still there isn't a robust glare metric, especially about daylighting. Many existing glare indices including DGP (Daylight Glare Probability), DGI (Daylight Glare Index), UGR (Unified Glare Rating), VCP (Visual Comfort Probability), and CGI (CIE Glare Index) focus on evaluating perceived degree of glare intensity. Method: This paper provides recommendations to determine discomfort glare in daylight space based on simulation and questionnaire in Iran and compares five different glare indices. The metrics analyzed are Daylight Glare Index, CIE Glare Index, Visual Comfort Probability, Unified Glare Rating, and Daylight Glare Probability. For assessing these indices, a questionnaire was developed and by reviewing the simulation results and the questionnaire, it was determined which criteria is more applicable under different circumstances. Findings: It is found that DGP yields the most plausible results. UGR has the highest rate for assessing perceptible glare, DGI has acceptable accuracy for assessing imperceptible glare and the best performance of CGI is in intolerable glare scenes. VCP has the least degree of accuracy in each stage. VCP is not suitable for use in calculations of daylight glare. Discussion and Conclusion: Evaluating visual criteria with considering at subject evaluation shows that DGP is the best Index in different level of glare.

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