A study on dedicated outdoor air handling unit systems regarding the widespread of ZEB

Abstract

ZEB has been promoted in the building sector to realize energy conservation and carbon neutrality. This has caused changes such as a decrease in the room sensible heat load factor and an increase in the outdoor air load ratio. In this study, the systems with a dedicated outdoor air handling unit (OAHU) are evaluated as air conditioning systems that can flexibly respond to a changing heat load, and guidelines for rational design and operation are given. A case study is conducted to evaluate the indoor environment and energy performance of a conventional air handling unit (AHU) system and an OAHU system under the assumption of a reduction in internal heat gain intensity. The study results showed that the OAHU processed latent heat and reduced the number of uncomfortable hours by 78% compared to those for the AHU system during the cooling season for cases with reduced internal heat gain. Regarding system energy consumption, the OAHU system consumed 17% more energy than the AHU-system. Thus, the OAHU system maintained a better indoor environment than the AHU system at the cost of increased energy use. Based on these results, measures for reducing the energy consumption of the OAHU system are discussed.