Periodic theory of an open roof pond

This paper describes an analysis of the reduction of the heat flux coming into a room through a roof with an open water pond. A periodic analysis of the system, based on the linearisation of Dunkle's6 expressions for convective, radiative and evaporative losses, is presented. Numerical computation for the heat flux has been carried out for a typical hot day, the 19th of June, 1979, in New Delhi. These results were compared with those for a water-sprayed system. It was found that, for typical parameters, there are reductions in the maximum heat flux entering the room of 48% and 41% for the roof pond and water-sprayed systems, respectively (for a relative humidity of 0·8). The corresponding reductions in daily heat input into the room are 20% and 35%, respectively. Load levelling is, of course, much better in the case of the open roof pond.