Decarbonizing Heat: The Impact of Heat Pumps and a Time-of-Use Heat Pump Tariff on Energy Demand

Heat pumps have been proposed as the leading technology in the electrification of domestic heat and therefore could play a crucial part in the transition to low-carbon energy systems. However, there is very little causal evidence of the impact of heat pumps on energy demand and the impact of marginal prices to help optimize energy demand with heat pumps. We leverage a staggered roll-out of heat pumps from Octopus Energy Group to show that: (1) heat pumps have a large impact on energy demand, on average causing a 90% reduction in home gas use and a 61% increase in home electricity use – overall, households reduced total energy demand by 40% and carbon dioxide emissions by 36% in 2024 (with an average of 68% emissions savings over the lifetime of the heat pump); (2) a time-of-use tariff designed for heat pumps can provide large demand flexibility benefits, halving electricity consumption during the evening peak to help balance the grid, and that load shifting is possible on the coldest days and from all building types in our sample; (3) the marginal value of public funds of the current UK heat pump subsidy is £1.24 (for every £1 spent by the Government). Overall, we find that heat pumps can meaningfully decarbonize heat and subsidies to encourage heat pumps can be welfare-enhancing.