Heat pumps are not as environmentally friendly as often claimed, according to MPs and researchers, who point to a failure to address the powerful refrigerants used inside the devices. These refrigerants can have a climate impact hundreds of times greater than carbon dioxide if released through leaks or poor maintenance.
The issue has received little public attention, despite refrigerant emissions being recognised by governments and regulators as an important source of greenhouse gases.
MPs criticise government's net zero push
Former Conservative leader Iain Duncan Smith and MP Greg Smith told the Daily Star that heat pumps are "damaging the environment."
"The government is obsessed to the point of disaster over net zero," the MP said. "Heat pumps are very expensive to buy and fit. They are built and sold by China, which uses slave labour and yet the government turns a blind eye to such abuses."
Greg Smith, shadow parliamentary under-secretary for Business and Trade, called the pumps "duds" and said consumers need "more options."
"Yet again, eco-zealots have jumped up and down to grab at the first technology on the shelf - demanding everyone buys one or be condemned as anti-green, but guess what, heat pumps are found to be not that great for the environment after all," he said.
"Decarbonisation needs to lean into real technologies, the work of our great innovators over the long term and stop plumping for these dud products that have been rushed to market without a whole system analysis."
Refrigerant R-32's climate impact
Heat pumps often contain a substance called refrigerant difluoromethane, more commonly known as R-32, which causes serious environmental damage if it leaks. R-32 has a global warming potential of 675, meaning one kilogram causes 675 times the warming of a kilogram of carbon dioxide over a 100-year timescale.
Genevieve Plant, a researcher at the University of Michigan, voiced concerns about the damage heat pump gases can do. "Most refrigerants used today have large global warming potentials and so it is important to keep them out of the atmosphere," she said.
"They are growing in abundance and it is a problem that cannot be ignored as we become more dependent on these types of systems. This is the reality. Heat pumps have been pushed as a universal climate-friendly solution and I don’t know that there’s been quite enough consideration of all of the dimensions."
Government defends heat pumps
The Government offers grants of up to £9,000 to replace fossil fuel systems in homes. A campaign promoting the grants reads: "Heat pumps are three times more energy efficient than traditional boilers, meaning they’ll substantially reduce the carbon footprint of your home, and because they run on electricity, there’s potential to make bill savings too by using smart tariffs with cheaper off-peak rates."
A Department of Energy spokesperson said: "Heat pumps run on electricity, reduce carbon emissions by around 70% and save households over £100."
