Effect of system variation on air conditioning energy performance

Air conditioning is process of controlling the temperature and humidity of the air for certain zones or buildings to improve thermal comfort of occupants. In tropical climate country such as Malaysia, air conditioning is an essential equipment all year round. However, the air conditioner consumed major energy up to 57 % especially in commercial building. In this paper, a study is carried out to investigate different types of air conditioning systems by comparing their energy usage in a target building. Three types of system are being tested, namely direct expansion (DX) system, water chilled fan coil unit system and variable refrigerant flow (VRF) system. The simulation utilizes the EnergyPlus software, and the model is an office building with floor area 48 m2 and cooling load of 6500 W. It is observed that the DX system comparatively consumes the lowest energy consumption with savings of 34.8%. However, the design of such system must be carefully carried out since DX has the worst energy penalties when oversizing.