Indoor humidity behaviors associated with decoupled cooling in hot and humid climates

Radiant cooling with independent air dehumidification/ventilation is a complementary cooling and ventilation technology that has the potential to provide better thermal comfort, air quality and energy consumption than conventional all-air systems. However, in hot and humid regions, fears for the risk of condensation on ceiling panels limit its market penetration. To address this problem, in this paper, indoor humidity behaviors associated with decoupled cooling in hot and humid climates are investigated. Room mean temperature, mean humidity, maximum RH on the ceiling panel surfaces, annual condensation hours and annual primary energy consumptions are predicted with systems combining chilled ceiling with various air dehumidification and ventilation strategies, using a building energy simulation code ACCURACY. The effects of night air infiltration rates and the ratios of air flow rates of return air to those of fresh air on the indoor humidity performance and annual condensation hours are discussed. The results indicate that dehumidification and ventilation prior to cooling panels operation is required to reduce condensation risks in hot and humid climates. It is also revealed that a 1 h in advance dehumidification/ventilation in summer could completely eliminate the condensation problems.