The public spending watchdog has criticised the slow pace of the government’s heat pump rollout just days after ministers postponed an important scheme designed to increase the rate of installations. A report by the National Audit Office (NAO) has found that heat pump installations would need to accelerate 11-fold if the government is to reach its target for 600,000 heat pumps installed in homes every year by 2028. With the number of heat pump installations by December 2023 running at less than half the number anticipated, Gareth Davies, the head of the NAO, said the government’s progress in making households aware of low-carbon heating alternatives and encouraging them to take them up had “been slower than expected”. The report was finalised shortly before the government revealed last week that it would delay by a year a scheme requiring heating installers to fit more low-carbon heat pumps – which is expected to make the targets even harder to reach. The clean heat market mechanism, which was scheduled to take effect from next month, was designed to increase heat pump installations by requiring manufacturers to meet a gradually rising proportion of its installations with heat pumps or face a fine. The NAO said this mechanism, with a scheme offering grants for heat pump installations, was expected to deliver two-thirds of the installation target by 2028. Nick Winser, the commissioner at the National Infrastructure Commission, the independent government advisers, said the decision to delay the mechanism until April 2025 had “only made hitting these targets harder”. “The NAO highlights that government’s current plans appear insufficient to meet its ambition of installing 600,000 heat pumps a year by 2028 or helping the 8m homes who need to switch from fossil fuel boilers to electrified heating by 2035 to meet climate targets,” Winser added. The government has identified electric heat pumps as an important tool in driving down the emissions from Britain’s home heating, which make up almost a fifth of the UK’s greenhouse gas emissions. It wants to see 600,000 heat pumps installed per year by 2028 which is an eleven-fold increase on 2022’s 55,000 heat pump sales. By 2035, it wants to see up to 1.6m heat pumps being installed annually. A government spokesperson said the decision to increase the grants available to install a new heat pump from £5,000 to £7,500 had boosted applications by nearly 40%. Meanwhile, a government media campaign featuring advice and information on how heat pumps, insulation and solar panels can cut household emissions and energy bills is running on TV, radio and newspapers, and reaching 16.6m homes, the spokesperson said.