AbstractAn explicit expression for the periodic variation of thermal flux through a multilayered insulated hollow wall/roof, whose one face is exposed to solar radiation and ambient air and the other is in contact with room air at constant temperature, has been derived. to obtain optimum placement of insulation and airgap, numerical calculations for the heat flux through a multilayered insulated hollow wall/roof have been made for a typical hot day (26 May 1978) in Delhi. It is seen that for a given total thickness of concrete, best load levelling is achieved when the thickness of the outer layer is as small as possible. the effect of a water film on heat flux into the buidling has also been discussed.