Passive cooling of roof over composite climate in India

Abstract

Heat gain in buildings is a major problem in most climatic zones in India, especially in the study area of Nagpur in Maharashtra. It is particularly acute in the top storeys of buildings directly beneath the roof, where internal temperatures generally exceed the ambient temperature. To reduce the heat gain of roof surfaces a combination of sustainable reflecting and insulating materials – comprising broken glazed tiles laid on the roof surface and false ceiling tiles made of mineral fibre board, including sawdust and expanded polystyrene – is proposed. The materials are retrofitted over and under the existing concrete roof of a room in an educational building, which is then monitored for a year. The retrofitted materials are found to be light in weight (26 kg/m2), low in cost (£12/m2) and result in a 3·9 times increase in thermal resistance. The retrofitted roof provides an average 5·9°C reduction in temperature and keeps room temperatures under 27°C for 34% of the year.