Investigating the performance of an air-source heat pump coupled to heating and cooling system of a single-family house located in a hilly area with low outdoor temperatures

This article evaluates, through a combined experimental and numerical simulation approach, the energy and environmental performance of a conventional air-source heat pump (ASHP) interconnected with the radiant floor heating and fan-coil cooling systems of a single-family building located in a hilly area of Romania during the cold and warm seasons. Based on in situ measurements over 1 year, coefficient of performance (COP) values of 2.67-3.54 for heating and 1.97–3.05 for DHW production were obtained in every month of the season. Also, energy efficiency ratio (EER) values for cooling ranged from 9.89 to 12.32. Additionally, 2.28 and 5.90 were recorded as the seasonal COPs of the system (SCOP sys , SEER sys ) for the heating and cooling seasons, respectively. The analysis clearly shows the inverse relationship between COP or EER and CO 2 emissions. Two simulation models of thermal energy and ASHP COP (EER) for the heating and cooling of the residential house are also created using the Transient Systems Simulation (TRNSYS) program. Lastly, TRNSYS-based simulations are investigated and compared with the exploratory measurements; the simulations show high agreement and are validated. The results confirm the system’s efficiency in both winter and summer conditions and highlight the importance of proper sizing and intelligent control. The study supports the use of ASHPs as a sustainable solution for residential buildings in a continental temperate climate. • One-year in-situ monitoring of an ASHP system operating in various modes • Seasonal COP and EER, and CO 2 emissions analysed as functions of outdoor temperature • TRNSYS simulations validated using measured data from real operating conditions • Auxiliary energy use and system-level performance indicators are experimentally assessed • Practical performance insights for residential ASHP systems in hilly cold regions