Integrated Heat Pump and Seasonal Thermal Energy Storage Systems for Cold Climate Heating: A Systematic Literature Review

Abstract

Long heating seasons, low outdoor temperatures and high heating demand make efficient and reliable heating difficult in cold regions. Heat pumps are a low-carbon alternative to conventional heating, but their coefficient of performance (COP) depends on the source temperature and operating conditions: the COP of an air-source heat pump falls as the outdoor air temperature drops, whereas ground- and storage-based sources are more stable. Seasonal thermal energy storage (STES) can store heat when it is available and supply it when heating demand is high. This systematic literature review, conducted according to PRISMA 2020, examines integrated heat pump–STES configurations for cold-climate heating, covering technologies, performance, climatic and operational factors, economic and environmental aspects, and technical challenges. Studies published from 2021 to 2026 were retrieved from Scopus, Web of Science, ScienceDirect, SpringerLink, IEEE Xplore and Google Scholar. The search identified 1,755 records (1,720 from databases and 35 from reference lists); after duplicate removal and staged screening, 33 integrated studies were included and synthesised descriptively and thematically after full-text eligibility re-screening. Among the studies that could be classified, ground-source and air-source heat pumps, and borehole, phase-change and seasonal storage, were the most frequently studied technologies. The included studies indicate that the benefit of integration depends on heat-pump type, storage configuration, storage temperature, system size, thermal losses and control strategy, and that capital cost, infrastructure needs and site-specific constraints remain important barriers. Climate-specific optimisation, advanced control, standardised performance assessment and long-term field validation are the main priorities for future research.