Ian Henderson, the managing director of Boiler Plan UK, has written to Business Secretary Kwasi Kwarteng, urging him to extend the Green Homes Grant scheme until all its £1.5 billion budget has been claimed.

In the letter, he warns that without the widespread adoption of energy efficient measures in Britain’s homes, the government will face an uphill struggle if it is to achieve its zero-carbon target by 2050.

Ian, who has previously lobbied the government on the need to decarbonise homes, said: “Unless urgent action is taken to get the Green Homes Grant scheme back on track and make the whole process more efficient, it will have little effect on reducing domestic C02 emissions.”

He called upon Mr Kwarteng to continue the scheme beyond March 2022, when it is currently due to end, to ensure as many householders and landlords as possible can access the grants.

“Rather than a cut-off date, the Green Homes Grant scheme should remain open until all its £1.5bn budget is claimed – and the government should seriously consider increasing the fund even further.”

Since the scheme, administered by US-based consultancy firm ICF, was introduced five months ago, just five percent of the budget has been allocated to householders – with the Environment Audit Committee of MPs warning that, at this rate, it could take a decade to meet its aim of delivering improvements to 600,000 homes.

Ian, himself a qualified heating engineer, added: “Our homes are among the worst in Europe when it comes to energy efficiency and this situation must be addressed if this country is to reach net zero by 2050.”

As part of the shift away from fossil fuels, conventional gas boilers will be banned from new build homes within three years and phased out altogether by 2035 – with hydrogen boilers and air and ground source heat pumps the most likely replacement technologies.

He added: “Eight out of 10 UK homes are currently heated by gas, so the challenges are huge, with air source heat pumps in particular reliant on well-insulated homes, otherwise they simply cost more to run and have higher carbon emissions.

“No matter what the heating source, improving the energy efficiency of our housing stock will reduce fuel poverty and offset some of the higher costs involved in these low carbon alternatives.”

Boiler Plan UK, which is headquartered in Cramlington, Northumberland, has itself created a special Eco department, expected to launch next month, to help householders secure vouchers of up to £5,000 or £10,000, depending on circumstances.

The vouchers help fund the installation of low carbon heating systems, including air source heat pumps, biomass and solar, together with insulation work. Grants are also available for a range of other measures including draught proofing, replacement doors and windows and heating controls.