Homeowners should be given special loans to allow them to make their houses more energy efficient, the Liberal Democrats have said.
The Lib Dems believe houses waste too much energy
The so-called "energy mortgage" could be used for double-glazing, insulation or heating systems.
The loan would be tied to a property, with house-buyers having to pay for changes carried out by previous owners.
Lib Dem leader Sir Menzies Campbell said the move would help to cut carbon emissions and reduce energy bills.
Housing is responsible for about 27% of Britain's carbon dioxide (CO2) emissions, the party says.
Hundreds of pounds worth of energy from every home simply escapes into the atmosphere every year.
The Lib Dems claim their proposals could save 31 million tonnes of CO2 - equivalent to the amount produced in 18 months by all the cars on Britain's roads.
Sir Menzies is due to outline the plans in south London on Monday.
He will say: "People are paying high fuel bills because their homes too easily lose energy.
"Our proposals will help people save the environment and cut bills."
'Raises the bar'
Repayments for any improvement work would be added to the property's fuel bills.
Lib Dem environment spokesman Chris Huhne said the work would eventually pay for itself.
"Millions of people struggle to pay their fuel bills each winter, yet are unable to afford improvements on their homes to make them more energy efficient," he said.
"With an 'energy mortgage', proven improvements will deliver real energy cuts that... will be accessible to everyone.
The party's Climate Change Starts at Home package was welcomed by environmental groups including WWF-UK.
A WWF spokesman they were impressed with the "scope, ambition and credibility" of the scheme.
"It is good to see political parties getting to grips with the environmental challenge we face, and this policy raises the bar for other parties to match."