Experimental determination of comfort benefits from cool-roof application to an un-conditioned building in India

Abstract

AbstractIncreasing roof reflectance helps in savings in air-conditioning energy consumption, increase in indoor comfort at the building level and mitigates Urban Heat Island effect, reduces net solar radiation absorbed by the earth, lowers local air temperature and pollutant formation, and reducing global warming at the macro level. Previous studies have demonstrated energy savings in buildings using cool roofs. However, not many have evaluated the indoor comfort benefits of cool roofs for unconditioned interior spaces, especially in India. Here, we describe a study of an un-conditioned, institutional building in a composite climate in India. Monitoring was performed for a period of six months (January to June 2012) on two adjacent sections of continuous concrete roof surface, one of which had been previously coated with a white paint coating. The measured shortwave band-averaged (0.3–3 µm) solar reflectance was 0.28 and 0.57, for the uncoated and coated surfaces, respectively. The increased reflectivity reduced the seasonal average indoor air temperature and heat flux by 1.07°C, and 14.4 W m−2, respectively, with peak reductions of 1.38°C and 18.3 Wm−2 in April 2012. This increased the number of adaptive comfort hours by 80 h (about 8% increase compared to dark roof), providing a significant improvement in human comfort.Keywords: cool roofsinstitutional buildingun-conditional buildingcomfort improvementair temperature AcknowledgementsWe gratefully acknowledge Prof K.P. Singh for assistance in arranging fieldwork at the G.B. Pant University. We also thank Ken Reichl for assistance with radiometer instrument preparation and initial data reduction. We thank Bipin Shah (Winbuild) who managed the cool roof project, which was supported by the US DOE Offices Energy Efficiency and Renewable Energy, and the US DOE Office of Science, Atmospheric Radiation Measurement program under contract DE-AC02-05CH11231.