Energy analysis on VAV system with different air-side economizers in China

The economizer is admittedly considered as one of the popular energy conservation measures in VAV systems. To evaluate potential energy conservation brought by the economizer scheme, the year-round energy simulation program is developed. Two types of air-side economizers, i.e. the temperature-based economizer cycle (TEC) and the enthalpy-based one (HEC), are introduced in the year-round operation of VAV system. The potential energy savings of the two economizer cycles are investigated in a representative office building exposed to the six typical climatic conditions in China. Simulation results indicate that the air economizers will achieve a higher energy-saving ratio in the southern China typically having hot-humid climates than applied in the northern China characterized by dry-cold climatic conditions. The HEC scheme is proved to be much more energy-efficient than TEC under the hot-humid climatic conditions, but not necessarily better than TEC under the dry climates. Increasing the temperature set-point of indoor air is beneficial to further improve the energy-saving performance of the both air economizers.