Enhancing the performance of modularised Fan Coil Units using the concept of Single Coil Twin Fan System

Abstract

Fan coil unit (FCU) design is attractive due to its inherent flexibility in usage that also leads to energy saving potential. However, design and operational issues often lead to problems of poor humidity control, inadequate ventilation and deteriorating IAQ, particularly in hot and humid climates. The decoupled ventilation concept of Single Coil Twin Fan (SCTF) air-conditioning and air distribution system that has been developed for air handling unit applications is now extended to FCU designs. Two SCTF FCUs were designed for a multipurpose classroom in the existing 3-storey training block in the first-ever retrofitted Net Zero Energy Building in Singapore. The design cooling loads demanded a high quantity of outdoor air for ventilation requirements and resulted in almost 50% of the cooling loads due to latent cooling. This paper presents the design of the SCTF FCUs including that of the unique compartmented cooling coils, which result in adequate ventilation and enhanced thermal comfort and IAQ at all times.