Optimized control strategies for an integrated heat pump environment control unit with outdoor air in different climate zones
An integrated heat pump environment control unit with outdoor air (IHPECU), as a key environmental control device for nearly zero-energy buildings (NZEBs), can achieve multiple functions such as heating, cooling, and ventilation; however, its complex operational mode switching often leads to high energy consumption. Therefore, the present study proposes and evaluates optimized control strategies tailored to the climatic characteristics of different regions in China, aiming to enhance the operational energy efficiency of IHPECUs. Based on the TRNSYS dynamic simulation platform, a coupled model of the building and the unit was established, with a key focus on analyzing demand-controlled outdoor air strategies based on indoor CO2 concentration during the heating season and free cooling utilization strategies based on the electronic enthalpy method during the cooling season. The results show that: during the heating season, adopting CO2 demandcontrolled outdoor air strategies, while ensuring indoor air quality, can reduce the total system electricity consumption in cities such as Harbin, Beijing, and Wuhan by over 10%; during the cooling season, optimizing electronic enthalpy control parameters and outdoor air volume for natural cooling source utilization can reduce total energy consumption by 2%-5% in severe cold and cold regions. Furthermore, in severe cold regions, proper window opening behavior can additionally reduce cooling season energy consumption by approximately 16.8%. These findings offer theoretical insights and quantitative support for the energy-efficient design and intelligent control of IHPECUs across diverse climate zones and demonstrate strong potential for engineering application.