Only a handful of councils across the UK with small social housing portfolios have ensured all their properties are deemed energy efficient, underlining the challenge the country faces in reducing emissions from its “leaky” homes.

The findings by Climate Emergency UK, a non-profit organisation that scores councils on green measures, come just days after Prime Minister Rishi Sunak said he would roll back energy efficiency measures aimed at the private rental sector.

Britain has some of the oldest housing stock in Europe, making it leaky and inefficient. About a fifth of the UK’s greenhouse gas emissions come from buildings and energy efficiency measures are seen as a relatively straightforward way to reduce them.

The non-profit compiled the data from freedom of information responses from 200 of the 300 local authorities that are allowed to own or manage social housing. The other 100 said they did not have a portfolio.

In total, 18 councils said at least 90 per cent of their properties had an EPC rating of C or above, including several councils with large housing stock, such as Manchester with 15,000 homes and East Renfrewshire with 3,000.

The EPC rating system works on a scale from A to G, with A the most efficient. Although Sunak scrapped plans to force private landlords to upgrade their properties to C by 2028, the government retained its target that all homes in England and Wales reach that level by 2035. Scotland has a more ambitious target of a B rating by 2032 on as many properties as is feasible.

Properties with a C rating or above have either been built using energy-efficient methods or have been upgraded through measures such as the installation of insulation or double glazing.

The five local authorities with a 100 per cent minimum efficiency rating all had much smaller portfolios, including Bradford with 400 properties, Hart District council with 41 and Wirral with 23.

About 40 local authorities reported having less than half of their portfolios with a C rating or above, including some of the biggest council housing providers such as the London borough of Barking and Dagenham at 42 per cent, Harlow at 41 per cent and Birmingham at 32 per cent. Mansfield was one of the worst performers at just 2 per cent.

“If the UK government and Rishi Sunak cared about providing warm homes, and saving consumers money they would provide a fully funded programme for all council homes to reach a minimum requirement of EPC C by 2028,” said Isaac Beevor, co-director of Climate Emergency UK.

Jennie Chilton, partner at law firm Addleshaw Goddard, said financial pressures meant local authorities were struggling to carry out the work. “Social landlords generally want to decarbonise their housing stock, but simply don’t have sufficient funds,” she said.

Birmingham city council, which in effect declared itself bankrupt earlier this month, said it was “working towards targets to make efficiency upgrades that reduce carbon emissions and energy bills for the homes that need it most.” The council has a target to bring all properties to a minimum of EPC C within seven to 10 years.

Mansfield executive mayor Andrew Abrahams said upgrading “thousands of homes is a huge task that needs long-term funding”, but added that the council was “committed to doing everything we can to reduce energy bills and provide energy-efficient homes”. 

Barking and Dagenham said it had “led a proactive campaign to retrofit many properties in the borough” and had made “hundreds of properties” more energy efficient.

Harlow said it was “prioritising energy efficiency works alongside making significant investment into improving our tenants’ homes”.

The government said that, thanks to its support, “the proportion of homes in England with an EPC rating of C or above is up from 14 per cent in 2010 to 47 per cent in 2022 and around 70 per cent of social housing are already at EPC C”.

“The government committed to spend £3.8bn through the Social Housing Decarbonisation Fund over a 10-year period to improve the energy performance of social rented homes — so far, we have committed £1bn and expect to announce further funding in due course,” it added.