In view of the imperfection of present efficiency region of multi-split air conditioning system based on energy efficiency ratio at nominal working condition

a concept and a determination method of seasonal efficiency region of multi-split air conditioning system based on seasonal energy efficiency (SEER) and annual performance factor (APF) were proposed. The construction approaches of full condition performance models of multi-split air conditioning system and air-cooled water chiller & heater unit plus fan-coil air conditioning system based on experimental data were illustrated. Using the building load model and air conditioning hours at various temperatures in cooling and heating season in GB/T 18837 (draft for approval)

the seasonal efficiency region of multi-split air conditioning system with different nominal energy efficiency ratio (EER and COP) in office building in Nanjing was calculated as an application example. The proposed concept and determination method of seasonal efficiency region of multi-split air conditioning system can not only provide an option to improve the code for engineering design of multi-split air conditioning system

but also offer guidance for the selection of air conditioning system and equipment in a practical project.