Four out of five Waltham Forest homes pay hundreds more in energy bills than they should each year due to poor insulation.

About half of the borough’s approximately 110,000 homes are more than a century old and leak heat through uninsulated solid walls.

After the energy price cap rose by almost £700 in April – and is set to rise again in October – there is a growing concern that more and more local households will be pushed below the poverty line by the cost of bills.

At a housing scrutiny committee meeting on April 20, Waltham Forest councillors discussed the urgency of “retrofitting” the borough’s older homes – improving their insulation to save money and lower emissions.

However, at a “conservative” estimate, bringing all local homes up to a good standard of energy efficiency would cost an average of £13,000 each – and £2.9bn in total – according to Retrofitting London.

Head of housing strategy James McHugh told councillors this week that retrofitting is “the clear and obvious solution to fuel poverty and climate change”.

He added: “This should follow a “fabric first” approach, in which the insulation of a home is improved prior to the installation of low-carbon heating measures, such as heat pumps, to ensure a reduction in fuel bill costs for residents.”

Of the 12,000 homes that the council directly manages, nine out of every ten have an Energy Performance Rating of C or below, on a scale that goes from A to G.

Officers estimate it would cost £82 million to improve them and, so far, government grants have only been secured to improve insulation on less than 300.

McHugh said he felt “hopeful” the council would secure more funding and that heat pumps, which can replace boilers, will become cheaper.

However, he added: “I suppose there’s a risk of inaction. If we wait too long, we will reap the short to medium term consequences.”

The council estimates homes make up just under half of the emissions in the borough, much of which come from gas boilers. One in five households in the borough are also thought to be living in fuel poverty, meaning the energy inefficiency of their homes brings them below the poverty line.

Private homeowners, who make up three quarters of the borough’s residents, are unlikely to see their homes made more heat efficient in the near future without paying themselves.

To demonstrate how older buildings can be improved Waltham Forest built an Eco Show Home at Greenleaf Road, cutting fuel bills by two thirds and raising its EPC rating from E to A.

Fuel poor private households may be eligible for support from local charity, The HEET Project, which the council says has supported 125 households in cutting their bills by £500 a month.