Effects of Albedo in Urban Planning - Special Reference to Building Roofs

Abstract

Surface albedo is defined as the ratio of irradiance reflected to the irradiance received by a surface wherein the proportion reflected is not only determined by properties of the surface itself, but also by the spectral and angular distribution of solar radiation reaching the Earth’s surface. Albedo is an important concept in climatology, astronomy, and environmental management including urban planning. Any albedo in visible light falls within a range of about 0.9 for fresh snow to about 0.04 for charcoal, one of the darkest substances [1]. One of the land surface properties that has been changed due to urbanization is albedo which is ranging from 0 (complete absorption) to 1 (complete reflection). Roofs and pavements, which constitute about 20-25% and 29-44% respectively of typical urban surfaces, generally have lower albedos than their surrounding areas. An effort has been made by the authors in the present paper to discuss the effect of albedo in urban planning with emphasis on building roofs.