Effect of using a reflecting sheet in an air gap on the thermal performance of hollow walls and roofs

In this paper, the effect of placing a reflecting sheet in an air gap on the thermal performance of single hollow, double hollow and insulated hollow walls and roofs is studied. One face of the wall or roof is exposed to solar radiation and ambient air and the other is in contact with room air at constant temperature. These results are also compared with the predictions made in the case when a water film is maintained on the roof or wall. Numerical calculations are for a typical hot day (the 26th of May, 1979) in New Delhi. It is seen that the use of a reflecting sheet in single hollow and double hollow walls and roofs is more economical--and gives a better performance--than the water film system.