Nationwide is doubling the number of homeowners who can take out interest-free loans to improve the energy efficiency of their homes.

The building society has announced that it will allow up to 10,000 mortgage customers to borrow at 0%. Eligible borrowers can take out between £5,000 and £20,000 to fund upgrades such as solar panels, insulation and new windows. The move expands its 0% Green Additional Borrowing scheme, first launched in June 2023, which initially aimed to help 5,000 households.

Nationwide said it has already lent around £60million through the scheme, with the average loan about £13,000. The South West has seen the highest take-up so far, accounting for 16% of completions, followed by the Outer Metropolitan and Outer South East regions, both at 12%.

Housing remains a major source of emissions in Britain. Around 20% of emissions in England come from residential buildings, according to government data cited by the lender.

Research by Nationwide and WPI Economics suggests improving all homes to Energy Performance Certificate (EPC) band C or above could reduce emissions from residential housing in England by up to 47%.

Henry Jordan, Nationwide’s group director of mortgages, said: “We are committed to helping our members improve the energy efficiency of their homes. Extending our zero per cent Green Additional Borrowing products will help another five thousand households who want to retrofit their home and can afford long-term investment but struggle to meet the upfront costs.”

He added: “However, more is needed and collaboration is crucial if we are to decarbonise the UK’s housing stock. We are, therefore, delighted to be part of the Green Home Finance Strategic partnership, which will play a leading role in helping to unlock the changes needed to make our homes resilient for the future.”

The expansion coincides with Nationwide joining the Green Home Finance Strategic Partnership, a scheme involving the Government and the Green Finance Institute to boost funding for home energy upgrades as part of the Warm Homes Plan.

Ryan Jude, programme director at the Green Finance Institute, said: “Expanding and diversifying the range of green finance options available will be critical to enabling more households to upgrade the energy efficiency of their homes.

“Nationwide’s extension on 0% Green Additional Borrowing mortgage offer is an important example of the range of options that will be needed from lenders to support the transition.”

Alongside the loans, Nationwide also offers a Green Reward scheme giving £500 cashback to buyers purchasing the most energy-efficient homes (EPC-A rated, SAP score 92 or above) and £250 for high EPC-B homes (SAP 86–91).

Since the reward scheme launched, the lender has paid out around £4.8million in cashback, including more than £1.7million between February 2025 and January 2026.

Nationwide also provides a Home Energy Efficiency Tool, developed with the Energy Saving Trust, to help homeowners assess upgrades and potential energy savings.

Since 2023 more than 20,000 people have used the tool, with over 80% completing an energy savings plan.

One borrower, Andrew from Norfolk, used a £12,000 interest-free loan to install solar panels on his bungalow.

He said: “I’d been looking at ways to reduce my energy bills and also help green my home. With a large south facing roof, solar panels seemed the obvious choice.

“However, the upfront costs for installing a suitable system were a bit prohibitive, so using Nationwide’s Green Additional Borrowing was the perfect solution. I could borrow the money needed and do so interest-free.”