hybrid active/passive system; solar collection cum storage system; ambient air temperature; heat retrieval plane
This communication presents a theoretical model of a hybrid active/passive system for space heating of a non-airconditioned building. The system consists of an underground air heater as solar collection cum storage system coupled with a non-airconditioned building to be heated. The model takes into account the periodicity of the solar intensity and ambient air temperature, recirculation of room air through an underground air heater, as well as periodic heat transfer to the ground, walls/roof and furnishings as a function of time. The effects of air heater design and other building parameters on the indoor room air temperature have been studied. It is found that room air temperature decreases with increasing depth of the heat retrieval plane and increases with increasing air mass recirculation rate. The thermo-physical properties and the surface conditioning of the soil above the plane of heat retrieval significantly improve the air heating efficiency of the proposed hybrid system.