The lender has reduced rates by up to 0.69% on selected 2-, 3- and 5-year fixed rate products.
According to the society, the aim is to encourage people to make their home more environmentally friendly by offering cheaper rates for green home improvements.
Improvements include the installation of solar panels, boiler upgrades, traditional insulation and electric vehicle charging stations.
The loans are only available to existing mortgage members.
Henry Jordan, director of mortgages, Nationwide, said: “It’s becoming ever clearer there is an urgent need to reduce the carbon emissions from our homes.
“We believe meaningful incentives are the only realistic way to help people make their homes more sustainable, which is why we today launched our new Green Additional Borrowing product.
“This new loan is the first product we are launching as part of our wider commitment to make £1 billion available to kick-start green home improvements.
“With more than 1.5 million homes on our mortgage balance sheet, we believe offering this new loan can make a real difference as we play our part in helping to tackle the climate crisis and help members to do the same.”
