Solar passive cooling/heating of building at Bikaner in Rajasthan, India

Abstract

The buildings of Bikaner are reasonably comfortable indoors because of thermal damping by the massive roofs and walls. However, the average indoor air temperature (over 24 hours) is about the same as the average outdoor air temperature. In a light-weight building without any external glazing and without any ventilation, the average indoor air temperature is the same as the area weighted average of the sol-air temperature of external surfaces, which is bound to be higher than the average outdoor air temperature. It is an indication of the effectiveness of the natural cooling methods used at Bikaner that the indoor temperatures equal the outdoor air temperature. The indoor temperatures in Bikaner lie just at the edge of the comfortable range. In other climates with higher relative humidity it is possible that inspite of good building design comfortable indoor conditions cannot be ensured because the average outdoor temperature is too high. In such climates it is necessary to adopt measures to lower the average indoor temperature to a level below the outdoor. Specially designed mud walls are still poplar in the hamlets (Dhanies) of western Rajasthan to deflect the hot winds. These are some of the conventional methods of passive cooling, typical in hot and dry climatic condition. India has a very diversified climate heating of buildings in also required especially in upper latitudes and hilly areas and cooling of buildings is required in lower latitude and desert areas. Solar passive architecture provides proper orientation and design of fenestration i.e. doors and windows to take maximum advantage of sun and wind. For heating the aim is to admit the sun's energy as much as possible and to reduce he loss of heat in the nights. This is achieved by direct gain through windows, therm-wall, or solarium and other such means. The heat loss is minimized by the proper design of walls, by insulation of walls and roof, by night insulation on windows, by double glazing of windows etc.