Methodology of avoiding condensation and downdraft in displacement ventilation plus cooling ceiling system

Puts forward the method of covering the cooling ceiling with the diathermanous film having high penetration rate for long wave radiation, and there being a layer of air or vacuum between the ceiling undersurface and the film. Measures the temperature, velocity and concentration fields in an office. The results show that the film temperature is equal to or greater than the average temperature of ceiling undersurface and indoor air, making the condensation on the film and ceiling much less possible, the downdraft reduced, and the cooling capacity of the cooling ceiling almost kepts unchangeable.