In this paper the thermal performance of an air space in an inclined roof and the optimum number of air spaces are discussed. One face of the roof is exposed to solar radiation and ambient air and the other is in contact with room air at a constant temperature. It is found that, for the desired thermal performance, the roof should always be horizontal. It is also inferred that dividing an air gap into a number of gaps reduces the heat flux coming into the room. At most, one may effectively use only four air gaps. The effect of using reflecting sheets in the air spaces has also been investigated. To achieve the best thermal load levelling, the outer concrete leaf should be of least thickness.
