Shifting Heat Sources Between Ground-Source Heatpumps and District Heating: A simulation study on the economic impact of hourly energy prices on residential hybrid heating systems

Abstract

In recent years, Sweden’s residential energy market has become increasingly complex. Energy prices for electricity and district heating have been steadily increasing. During 2022, fluctuations in electricity prices reached new heights, and interest in energy-smart, price-governed hybrid heating solutions has since grown. This master thesis aims to analyze the potential economic gains in yearly energy costs using a heating system that shifts the energy source between district heating (DH) and a ground-source heat pump (GSHP) based on hourly energy prices. The economic evaluation is conducted in greater detail by developing and validating a simulation model incorporating the specific system with the building energy simulation software IDA ICE. The evaluation showed that varying spot-price levels for electricity and fees for power subscriptions for DH significantly influence yearly energy costs. Using electrical spot prices from 2021-2023 demonstrated that the hybrid solutions had approximately the same yearly energy costs, even though the amount of shifted energy varied. Comparisons with solutions involving only DH or GSHP as heating providers, based on the electrical prices in 2022, revealed the sensitivity to electric spot price levels, making it difficult to distinguish between the yearly costs for hybrid or GSHP systems. The study could not show that the evaluated hybrid configuration had lower yearly energy costs than only GSHP. Since combining DH and GSHP will come with higher investment costs than choosing only one, customers may need other motivational factors to invest in a hybrid heating system. The conclusion is that although this system type could provide benefits such as redundancy and flexibility for property owners and energy suppliers, it is not currently promoted under the existing DH price models. To increase the adoption of such systems, refinements of price models are encouraged. This kind of system can play an important role in the future energy landscape; by combining the effective heat pump technology with the robustness of the district heating network, the hybrid system could help balance both the district heating and electrical networks if utilized correctly.