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

Subject Areas : Architecture and urbanism

mahbubeh pourahmadi ¹ , mohammadali khanmohamadi ² , farhang mozafar ³

1 - PhD Candidate, Architecture, Iran University of Science and Technology, Tehran, Iran
2 - Associate Professor, Architecture, Iran University of Science and Technology, Tehran, Iran* (Corresponding Author)
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.

References:

1. Wienold J, Christoffersen J. Towards a new daylight glare rating. 2018;(November).


2. Bodart M, Cauwerts C. Assessing daylight luminance values and daylight glare probability in scale models. Build Environ [Internet]. 2017;113:210–9.


3. Suk JY, Schiler M, Kensek K. Investigation of existing discomfort glare indices using human subject study data. Build Environ [Internet]. 2016;1–10.


4. Jakubiec J RC. The “adaptivezone” – a concept for assessing discomfort glare throughout daylit spaces. Light Res Technol. 2012;44(2):149–70.


5. Van Den Wymelenberg K, Inanici M. A Critical Investigation of Common Lighting Design Metrics for Predicting Human Visual Comfort in Offices with Daylight. Leukos. 2014;10(3):145–64.


6. Hirning MB, Isoardi GL, Coyne S, Garcia Hansen VR, Cowling I. Post occupancy evaluations relating to discomfort glare: A study of green buildings in Brisbane. Build Environ. 2013;59:349–57.


7. Tuaycharoen N, Tregenza PR. View and discomfort glare from windows. Light Res Technol. 2007;39(2):185–200.


8. Hirning MB, Isoardi GL, Cowling I. Discomfort glare in open plan green buildings. Energy Build. 2014;70(2):427–40.


9. Guth SK. A method for the evaluation of discomfort glare. Illum Eng. 1963;58(5):351–46.


10. IES. Outline of a standard procedure for computing visual comfort ratings for interior lighting. J Illum Eng Soc. 1966;61(10):643–66.


11. Harrold, R., D. Mennie AI. ESNA lighting ready reference: a compendium of materials from the IESNA lighting handbook. Illum Eng Soc North Am. 2003; 36(5):132–46. 


12. Einhorn HD. Discomfort glare: a formula to bridge differences. Light Res Techno. 1979;11:90–4.


13. Nazzal AA. A new evaluation method for daylight discomfort glare. Int J Ind Ergon. 2005;35(4):295–306.


14. Chaiwiwatworakul P, Chirarattananon S RP. Application of automated blind for daylighting in tropical region. Energy Convers Manag. 2009;50:2927–43.