A review of environmental assessments of ground-source heat pumps

Ground source heat pumps (GSHPs) are considered to be a promising technology to improve the energy efficiency of heating and cooling in buildings. However, sustainability of heat pump technologies and in particular GSHPs can sometimes be questioned. Detailed investigation of the environmental impacts of GSHPs over all stages of their life is needed to evaluate their sustainability. In this article, studies focused partially or in full on the environmental impact assessment of GSHPs, and their integrations with other systems, are reviewed. The focus of the review is on the main findings of such studies to provide a clearer picture of their status, but a summary of data input and methodologies that are used in such studies is also provided to ensure meaningful comparisons can be made among results of various studies, and to guide new studies on environmental assessment of GSHPs. It is found through this review that the main life stage contributing to environmental impacts of GSHPs is operation stage and the main contributor during this stage is electricity generation mix. Improvements in electricity generation source seem to be the most important factor to be considered if a wider adoption of GSHPs is sought. • Environmental impact assessments of ground-source heat pumps (GSHPs) are reviewed, including Life cycle assessments (LCAs). • A summary of data input and methodologies that are commonly used is provided to guide new LCA studies in this area. • Results of LCAs made to compare GSHPs with other heating and cooling technologies are reported and compared where feasible. • Validity of the results and how one might draw conclusions based on the results of LCAs on GSHPs is discussed. • The common results of LCAs and what factors could potentially improve their environmental performance are reported.