In this study, a comparative life cycle assessment of different heat pump technologies based on multiple supply chain scenarios according to the UK market has been conducted. In addition to conventional heat pumps – air-source heat pump (ASHP), ground-source heat pump (GSHP), and water-source heat pump (WSHP) - a novel hydrogen-source heat pump (HSHP) has been studied from an environmental aspect. Different supply chain scenarios have been developed for all technologies based on the leading supplier of heat pump components in the UK. Results showed that the manufacturing and operation of heat pumps are the main causes of the environmental impacts. Among the four technologies studied, ASHP had the highest negative environmental impacts across most categories. HSHP stands out with notably lower carbon emissions compared to other cases. However, in certain impact categories, HSHP exhibited more significant consequences, especially concerning land use and land-related pollution. Regarding CO2 emissions, ASHP is projected to achieve the most substantial reduction, with expected reductions of 23 %, 60 %, and 97 % by 2030, 2040, and 2050, respectively. GSHP, WSHP, and HSHP are also predicted to experience significant CO2 emission reductions of 94 %, 95 %, and 59 % by 2050, aligning with the UK's net-zero goal.