Investigating Annual Sunlight Exposure (ASE) as an Indicator for Overheating in a free-running building: a case of thermal comfort improvement in a child development centre in Thailand

Abstract

Annual Sunlight Exposure (ASE) is widely used to assess direct sunlight exposure in the building as a proxy to detect potential visual discomfort. Even though ASE was not targeted at thermal comfort, the relationship between direct sunlight and thermal sensation has been known. The study aims to explore the associations of ASE and thermal comfort criteria through an improvement of thermal comfort in a Child Development Centre (CDC) in Thailand. An existing condition of a CDC building and a simplified version were simulated using the IESVE simulation tool. Overhangs, external shutters, and double glazing were integrated into the computer models to improve thermal comfort. CIBSE TM52 overheating criteria are used to indicate thermal comfort. We found significant correlations between ASE and the criteria of CIBSE TM52 (r=0.28-0.56; p<0.05), indicating that more thermal discomfort is significantly correlated with a higher percentage of direct sunlight area. However, ASE could not justify thermal comfort since it does not include other essential thermal comfort factors, especially sunlight intensity. Such that double glazing could improve overheating criteria but not ASE. Future studies incorporating essential factors according to different climates are needed.