As the demand for refrigeration and Air conditioning has been increased during the last decade, the cool storage systems can be used to the economic advantage over conventional cooling plants. Cool storage system using phase change materials can be used for peak load shifting if they are installed in the building.
In the case of sensible heat storage system, energy is stored or extracted by heating or cooling a liquid or a solid, which does not change its phase during the process. A variety of substances like water, heat transfer oils and certain inorganic molten salts, and solids like rocks, pebbles, and refractory are used. The choice of the substances used largely depends upon the temperature level of the application. Phase change material (PCM) are one of the latent heat materials having low temperature range and high energy density of melting – solidification compared to the sensible heat storage. The tests on transient heat transmissions across different roof structures were conducted. It was found that when installing PCM in the withering course (WC-mixture of broken bricks and lime mortar) region nearly uniform roof bottom surface temperature was maintained.

Keywords: Phase Change Material (PCM), Energy storage, Latent heat storage (LHS), Withering Course (WC), Natural Cooling, Building roof, heat transmission.