Decoupling dehumidification and cooling for energy saving and desirable space air conditions in hot and humid Hong Kong

The combined use of dedicated outdoor air ventilation (DV) and dry cooling (DC) air-conditioning system to decouple sensible and latent cooling for desirable space air conditions, better indoor air quality, and energy efficiency is proposed for hot and humid climates like Hong Kong. In this study, the performance and energy saving potential of DCDV system in comparison to conventional systems (constant air volume (CAV) system with and without reheat) for air conditioning of a typical office building in Hong Kong are evaluated. Through hour-by-hour simulations, using actual equipment performance data and realistic building and system characteristics, the cooling load profile, resultant indoor air conditions, condensation at the DC coil, and energy consumptions are calculated and analyzed. The results indicate that with the use of DCDV system, the desirable indoor conditions could be achieved and the annual energy use could be reduced by 54% over CAV system with reheat. The condensate-free characteristic at the DC coil to reduce risk of catching disease could also be realized.

► The combined use of dedicated ventilation and dry cooling (DCDV) system was investigated.
► Investigations were based actual equipment performance data and realistic building and system characteristics.
► DCDV system could save 54% of the annual energy use for air-conditioning.
► DCDV system could better achieve the desired space air conditions.
► DCDV system could decouple dehumidification and cooling.