Energy savings potential of chilled-ceiling combined with desiccant cooling in hot and humid climates

An heating, ventilating and air-conditioning (HVAC) system combining chilled-ceiling with desiccant cooling is proposed for hot and humid climates where air dehumidification is required to maintain the indoor air humidity within a comfort zone and to reduce the risk of water condensation on chilled panels. With this system, temperature and humidity control are decoupled by using desiccant wheel for moisture removal and ceiling panels for temperature control. To evaluate the system performance and the energy savings potential, another three systems: conventional all-air system, all-air system with total heat recovery, and radiant cooling with air handling unit (AHU), are considered for a typical office in Hong Kong. The hourly sensible load is calculated by a building energy simulation code ACCURACY and the latent load is predicted by moisture balance in the room. Through hour-by-hour simulations, the annual energy consumptions of the four systems are calculated and analyzed. The results indicate that chilled-ceiling combined with desiccant cooling could save up to 44% of primary energy consumption, in comparison with a conventional constant volume all-air system. More interestingly, more than 70% of annual operating hours for desiccant regeneration could be accomplished by low-grade heat of less than 80°C.