Toward optimal designs of domestic air-to-water heat pumps for a net-zero carbon energy system in the UK

Air-to-water heat pumps come with diverse design options whose cost and performance are correlated, giving rise to a crucial question: should manufacturers aim at designing higher-performance yet higher-cost heat pumps, reducing the wider energy infrastructure cost but increasing the upfront cost to end users, or more affordable yet lower-performance alternatives? Comprehensive heat pump performance and cost models are integrated within a whole UK energy system framework to capture how different heat pump designs influence the decarbonization pathway. We find that an uptake of higher-performance heat pumps leads to a reduced national electricity generation capacity. However, there is an optimal design that minimizes the total system transition cost, indicating a point of diminishing returns, beyond which, instead of investing in even higher heat pump performance, it is more cost effective to invest in centralized energy generation and storage. Insights are valuable for locations with low heat pump adoption and high electricity-to-gas price ratios.