The failure poses questions for the whole approach to decarbonising UK homes since heat pumps are the preferred appliance to be fitted to meet net zero under the previous government and under Secretary of State for Energy and Climate Change Ed Miliband.

In October 2021, when published, the Heat and Buildings Strategy promised heat pump costs would fall by at least 25-50 per cent by 2025, achieving price parity with a boiler by 2030. The EUA says, four years on, data obtained from the government’s preferred heat pump installation accreditation body, MCS, suggests costs have increased not fallen.

The EUA contends that in October 2021, the average heat pump installation cost £12,155.24. By October 2025 that figure was £13,699.46, a cash increase, but adjusted for inflation in real terms it equates to a fall of just 8 per cent. During this time, the size of heat pumps installed has fallen, but the cost per kWh of heat has risen from £1253.46 in 2021 to £1630.87 by 2025 (according to MCS). Adjusting for inflation, it shows that in real terms the cost per kWh has increased by 6 per cent.

Commenting on the findings, Mike Foster chief executive of EUA said: “However you look at it, the Heat and Buildings Strategy has failed to deliver the promised price cuts. The whole policy of heat decarbonisation now needs to be looked at again. The promised land of cheap heat pumps and lower bills have both failed to materialise. We need a new plan.

“The whole of UK energy policy has been geared towards heat pumps being affordable and providing millions of homes with cheap, clean heat. It hasn’t happened, so this government needs to put right what the previous one got wrong.

“Realistic plans are needed to give consumers and taxpayers a proper estimate of costs they and the country will face.