Amid a national policy push promoting heat pump adoption to decarbonize the U.K. economy and reduce reliance on fossil fuels, researchers sought to determine the most cost-effective air-to-water heat pump technologies.

Data from over 100 commercially available products were used by analysts from Imperial College London and the University of Cyprus to develop a thermodynamic and component-cost model of residential heat pumps. The assessment considered scientists grouped the heat pumps based on three different compressor types — reciprocating-piston, rotary vane and scroll compressor technologies — sized for a maximum thermal output of 10 kW, in addition to various working fluids and heat exchanger areas ranging from 0.5 m² to 4 m².

The average cost of reciprocating pistons, rotary vane and scroll compressors was determined to be £2,560 ($3,232.52), £790 ($1,002.31) and £2,690 ($3,412.94), respectively. The coefficient of performance (COP) ranges between 1.6 and 3.8; a higher COP can be attained with a greater capital investment in components. Ammonia offered the best performance of the working fluids evaluated, with the highest COP of 2.8 and the lowest levelized cost of heat.

Installed electricity generation capacity by technology in the U.K. energy system in 2050 and system cost of heat decarbonization for different domestic air-to-water heat pump designs of varying COP and price. Source: Cell Reports Sustainability 2024, 100021

[See also: The promise of heat pumps for UK homes]

Most high-performance and costly heat pumps had large heat exchangers and rotary vane or scroll compressors, while most low-performance and low-cost incorporated small heat exchangers and rotary vane compressors. The research published in Cell Reports Sustainability indicate that use of high-performance/high-cost heat pumps can substantially reduce the required electricity generation capacity by up to 50 GW, equating to a 20% reduction relative to the use of low-performance/low-cost units.