The EPC system, introduced in 2007, rates properties by energy efficiency, with the most efficient properties rated A and the least efficient G.
Official statistics show efficiency is generally higher in the social rented sector, with around 70% of properties rated A-C in 2022, compared to 44% in private rentals.
But that still leaves around 1.2m social properties in England below a D rating, in addition to 2.6m properties being rented privately.
The National Housing Federation, which represents housing associations, has previously put the average cost of bringing a social housing property up to level C at between £3,000 and £4,000.
Head of member relations Kevin Garvey said meeting Labour’s target would require housing association to double the current pace of retrofitting homes, as well as “clear plans for homes that are harder to decarbonise”.
“Housing associations need a commitment to long-term funding from the government to ensure they have the resources they need,” he added.
