Energy Conservation with use of Cool Roof Coatings

Abstract

Regions with hot and dry climate often experience very high levels of solar radiation, high ambient temperatures and relatively low specific humidity. The roofs of buildings in such areas are always exposed to Sun for long duration during the daytime. Solar radiation is responsible for heat transfer through the building roof. Actually, Solar radiation heat the roof which in turn reradiates the heat onto the ceiling and finally on to the room occupants. Traditionally, most of the roofs in the world are made with dark color materials. In summer, the temperature of surface of a black roof can increase as much as 65–90°C. At such a high roof temperatures the deterioration of roofing materials can start and this in turn leads to increased roof maintenance costs, and generation of high levels of roofing waste. To effectively overcome this problem the best solution to reduce this is with the use of radiant barriers, i.e., light colored metallic or non-metallic surfaces which have high solar reflectance and a high emittance to redirect the radiations back to the environment. A cool roof is one that reflects more sunlight and absorbs less heat than a standard roof. In general, cool roofs are made with a highly reflective type of paint or highly reflective tiles or shingles and a covering sheet. Practically, any type of building can be benefited from a cool roof, however, consideration of the climate and other factors are of utmost important before deciding to install one. The present article gives an insight into global roofing market, elastomeric roofing and cool roof coating technology; different cool roof coating materials, relative benefits of cool roof versus conventional roof in terms of energy and cost savings has been discussed at length.