The average person would only invest in making their property greener if their energy bills jumped by £56 a month, according to survey.
This was the tipping point at which they would make their home more energy-efficient, according to the research from Nationwide Building Society.
Half (50%) of the more than 2,000 people surveyed consider themselves environmentally friendly.
But 46% said they were worried about the cost of going green and 30% were concerned they would be overcharged due to finding green improvements confusing.
Claire Tracey, Nationwide Building Society’s chief strategy and sustainability officer, said: “Without encouragement and incentivisation nothing will likely change.”
Nationwide has made a £1 billion loan fund available for borrowers to reduce the carbon footprint of their homes and kickstart green home improvements.
It also offers a mortgage rate of 0.75% to its existing mortgage customers for additional borrowing.
At least half of the home loan must be used to fund a range of sustainable home improvements, including the addition of solar panels, air source heat pumps and electric car charging points.
Greenpeace UK’s director of policy Doug Parr said: “While it is absolutely vital for tackling the climate crisis that housing in the UK is given a low-carbon transformation, it cannot leave hardworking households out of pocket.
“Grants can be a welcome boost but we need the Chancellor to deliver a suite of funding and tax breaks in the upcoming spending review if we’re to succeed in greening the UK’s homes.
“That means fully funding energy-efficiency improvements and low-carbon heating for low-income families so they are not worse off from the transition. It also means support for other households to give the market the necessary kickstart it requires.”