Technological advancements in the utilization of renewable energy sources have unveiled potentials for increasing building energy efficiency. Integrating heat pump-based energy systems with thermal storages is a suitable option to meet the thermal requirements of modern buildings and exploiting the available renewable energy sources. However, how to size the main components of a heat pump-based energy system with the integration of short- and long-term storages is not yet well explored. Therefore, this study focused on the design and performance analyses of an integrated heating and cooling system consist of a heat pump, borehole long-term thermal storage, and hot water tank short-term thermal. Heat pump models were introduced as parametric models based on the producer data. The dynamic thermal model of the energy system was developed and analysed in MATLAB. Different combinations of heating and cooling loads were tested. Integration of cooling and heating systems was discussed through different operation strategies and challenges were addressed. The results of the parametric analysis identified the key parameters affecting the design of components and efficiency of the system. Moreover, the results showed that lower cooling to heating load ratio leads to an excessive reduction of the ground temperature and overall efficiency over the long-term operation.

Modern buildings in cold climates, like Norway, may have simultaneous heating and cooling demands. For these buildings, integrated heating and cooling systems with heat pumps, as well as short-term and long-term thermal storage, are promising solutions. Furthermore, combining this integrated system with renewables aids in the transition to future sustainable building energy systems. However, cost-effectively designing and operating such a complicated system is challenging and rarely addressed. Therefore, this research proposed an integrated heating and cooling system that incorporated a short-term water tank and a long-term borehole thermal storage. Meanwhile, three operating modes: heating, cooling, and free cooling were defined based on different heating and cooling load conditions. A detailed system model was developed in MATLAB using heat pump manufacture data as well as simulated and measured building loads. Following that, sensitivity studies were performed to investigate the impacts of ground properties, thermal storage size, setpoint temperature, heat pump characteristics, and load conditions. The findings identified the crucial factors that influence the system’s overall energy efficiency and the functioning of the key system components. Particularly, it revealed that low cooling to heating ratios caused an imbalance in charging and discharging, further reducing the ground temperature and degrading the heat pump’s performance.