Nightsky, an innovative night roof spray storage cooling system, provides chilled water to in-slab tubing and fan coils. Passive cooling delivery from the slab cools the building in parallel with the 'active' chilled-water fan coils. Delivering a significant fraction of the building's cooling requirements via the floor slab allows that size of the forced-air delivery system to be reduced. NightSky is most appropriate for large, low-rise buildings that have low-slope roof areas.
This is the first of a series of four papers that describe a 3-year EU-funded research project into the application of passive downdraught evaporative cooling to nondomestic buildings. In this paper various evaporative cooling techniques are reviewed. By spraying fine droplets of water at the top of atria, a downdraught of air cooled by evaporation can be produced. Such direct evaporative cooling using an evaporation tower appears to be a suitable approach for partly displacing the need for air-conditioning in hot, dry climates.
The transient performance of displacement ventilation has rarely been studied though many researches have been done on the area.. Due to the importance to the analysis and design of an air conditioning system, the unsteady histories of displacement ventilation of a typical office in Hong Kong is simulated numerically with a validated computational fluid dynamics (CFD) model. Solar heat gain is introduced from the glass wall. Turbulent flow with thermal convection is considered. As a preliminary research, the heat capacity of the walls, occupants and machines is ignored.
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