A review of passive systems for natural heating and cooling of buildings

Abstract

In the present era of energy crisis, energy required for heating and cooling of buildings is 6.7% of the total world energy. Utilization of natural heating and cooling systems which essentially consist of collection, storage, distribution, and control of thermal energy flow can save 2.35% of the world energy requirement. The basic methods of heating and cooling of buildings are: solar radiation, out-going longwave radiation, water evaporation, and nocturnal radiation cooling. Trombe-Michel wall consists of large concrete mass, exposed to sunlight through large, south facing windows, is used for heating the buildings. Solar absorption cooling and solar dehumidification and evaporative cooling are two approaches which utilizes solar energy for generation of working fluid and cooling the dwellings. Longwave radiations emitted by the surface of the earth to the atmosphere and outer space is very strong in a desert climate and is effective from a roof surface. Water evaporation by desert coolers is the method of cooling in arid regions. Nocturnal radiation both heats in winter and cools in summer, in suitable climates, and does so with no non-renewable energy other than a negligible amount required to move the insulation twice a day. The difficulty encountered in the utilization of natural energies is the large area exposed with suitable orientation for collection of energy and large space requirement for the storage of thermal energy. This paper reviews these passive systems for natural heating and cooling of buildings.