The union Unison is proposing an energy review of homes which it says will save money and reduce the need for fracking.
It suggests a free door-to-door assessment programme for households, that would identify remedial works required for every house to meet minimum energy efficiency standards.
It says this would save households between £300 and £600 each year.
Low-income households would receive the work for free, while others would be granted an interest-free loan.
Unison says the UK is "reaching crisis point with dwindling gas supplies", and adds that, within the next five years, the country will need to import up to 70% of gas from abroad.
The report comes in the wake of the Queen's Speech this month where the government confirmed it would press ahead with legislation that would allow fracking companies to run shale gas lines through private property without permission.
The fracking process involves pumping water, sand and chemicals into rock at high pressure, and it has sparked demonstrations by environmentalists. Some governments have banned the process.
Critics argue that fracking contaminates water supplies and can cause earthquakes. There have been strong anti-fracking protests at Balcombe, West Sussex, against test-drilling.
Unison's general secretary, Dave Prentis, said: "The government must take action to bring millions of households in from the cold. Unless the government invests in a long-term strategy to preserve our dwindling North Sea gas supplies, we will be relying on expensive imported energy and wide scale fracking for shale gas."
It claims the UK has the oldest housing stock in the European Union, with older houses requiring at least twice as much energy to stay warm as homes in similar developed nations.