14% of UK greenhouse gases come from our homes, a similar level to emissions from cars.
In major cities gas boilers are also a main source of nitrogen dioxide emissions.
The government wants low-carbon heat systems to be standard for all new homes built after 2025. But that will still leave the vast majority of existing homes in the UK with polluting heat systems.
The cross-party Policy Connect think-tank more than 20,000 homes a week must switch to low-carbon heating between 2025 and 2050 to meet UK climate goals.
The report’s lead author, Joanna Furtado, said: “The next five years are critical for heat decarbonisation in new and existing homes and for meeting our climate targets. We need to spark a national conversation on heat as MPs and consumers are still in the dark on the savings greener home heat solutions could offer."
Ministers have not yet produced policies to insulate Britain's homes - even though well-insulated homes are essential for some low-carbon heat systems. A report from the advisory Committee on Climate Change said it would cost £4,800 to install low-carbon heating in a new home, and £26,300 in an existing house.