Performance of different passive techniques for cooling of buildings in arid regions

Eight identical test structures each having dimensions 1280×610×1100 mm3 have been fabricated. All the four sides of the test structures were made by using mild steel angle and galvanised steel sheet. The reinforced cement concrete roof was casted over these. The different passive techniques were used over the roof for cooling the environment inside test structures viz. painting of roof with white cement, thermal insulation over the roof, nocturnal cooling i.e. shallow pond with 100 mm water column with 40 mm thick movable thermal insulation over the roof, evaporative cooling i.e. roof is provided with gunny bags soaked with water with the help of a storage tank and dripper for controlling flow of water without any pump, broken white glazed tile pieces stuck over the roof, air void insulation i.e. inverted earthern pots having 100 mm diameter and 125 mm height were provided over the roof, and roof covered with Sania, a local insulating material used over the huts in the arid regions and the controlled unit without any treatment. The evaporative cooling has been found best for conventional roof, but it requires about 50 l/m2 water per day, therefore, pieces of white glazed tiles stuck over the roof can be used to reduce heat load from the roof and hence cooling of the environment inside buildings.