The Liberal Democrats have pledged to reward people who improve the energy efficiency of their homes with a 10-year council tax discount under pre-manifesto plans.
Households could save at least £100 a year by permanently cutting their energy bills in a bid to help with the cost of living while simultaneously meeting Britain's climate change targets.
Energy Secretary Ed Davey said his was the only party offering both lower energy and council tax bills, adding: "A 10-year council tax cut will make action to end your home's energy waste a no brainer.
"And to meet our legal climate change obligations, the cheapest way is to make rapid progress in cutting our emissions by saving the energy we now waste.
"In Government, Liberal Democrats have already helped many people to save energy and keep their bills down, and we are on track to meet our target of improving the energy efficiency of one million homes but this major new tax incentive for energy efficiency would mean we could go much further in the next parliament.
"We cannot build a stronger economy without creating a greener, more sustainable economy too."
Anyone who improves the energy efficiency of their home by two energy performance certificate bands would have their council tax reduced by at least £100 for 10 years.
Ways of achieving this include replacing an inefficient boiler and insulating cavity walls or insulating a loft, replacing halogens with LED lights and installing solar panels.