Abstract：

Multi-split air conditioning systems, commonly used in residential buildings and small public buildings, are often considered to have unique advantages such as flexibility and high efficiency, and have been widely used in small and medium-sized commercial buildings, as well as some large office and residential buildings both domestically and internationally. However, with the growth of the market size, multi-split air conditioning systems have gradually revealed some pain points in practical applications. In this study, two in-use office buildings located in hot summer and warm winter zone and hot summer and cold winter zone of China are selected, and two sets of multi-split air conditioning systems are measured on-site by using the refrigerant mass flow meter method, the compressor performance curve method and the air enthalpy difference method. The results show that the energy efficiency of multi-split air conditioning systems that perform well under laboratory conditions shows a relatively significant difference from expectations in actual operation. The common issue of oversized equipment selection directly leads to the system operating for extended periods at low load rates, which not only increases the amount of refrigerant charged, raises the risk of leakage, but also leads to reduced energy efficiency. Moreover, the decentralized control of indoor units by users can lead to unreasonable operation, further affecting the system’s energy efficiency, and there is an urgent need to carry out energy saving commissioning for the multi-split air conditioning system.

Keywords:multi-split air conditioning system; field test; cooling system; operational energy efficiency; office building; refrigerant mass flow meter method; compressor performance curve method; air enthalpy difference method