A critical evaluation of variable air volume system in hot and humid climates

Abstract

Although the inherent advantages of a variable air volume (VAV) system in terms of its energy performance are well understood, the designer is often challenged with complications due to different building characteristics, varying climatic conditions and multiple zoning. In hot and humid climates, it is often found that the benefits of VAV systems are not fully realized. The main objective of this paper is to compare critically the performance of a VAV system with an equivalent constant air volume (CAV) system for five different buildings in such a climate, whose internal loads remain constant throughout but the thermal loads due to the building envelope and orientation vary among the five buildings. The presence of a diversity in cooling loads is thus investigated which then leads to the exploration of potential energy savings with a VAV system. A detailed analysis of the system and plant loads and the corresponding energy consumption for the two types of systems is presented and the extent of energy saving potential of a VAV system is identified.