Novel ventilation cooling system for reducing air conditioning use in buildings.

Night-time cooling of buildings is a recognized way of reducing the use of air conditioning, and hence energy consumption. The paper describes the construction and testing of a latent heat storage system, which uses a novel combination of night cooling, heat pipes and phase change materials (PCMs) and has the distinct advantage that it is suitable for fitting to existing buildings. The design of the heal pipe/PCM heat storage unit is briefly discussed. The lest rig was constructed in a room of approximately 14 m2 floor area, and consisted of a number of heat pipe/PCM units mounted radially close to the ceiling with forced convection from a large propeller fan. At night, cool outdoor air is passed over one end of the heat pipe to freeze the PCM. During the day, warm air from the room is circulated over the heat pipe to melt the PCM and thereby cool the air. Test results from the prototype over a range of summer weather conditions are presented, showing a significant heat storage during the summer day with little external energy input. The advantages of the system compared to existing concrete beam systems are briefly described.