Just last month, Mr Swinney hailed the opening of Scotland’s first hydrogen homes as a “shining example” of how the country is leading the way in solutions to tackle climate change.

And as the Scottish Government prepares to draw up legislation to end the use of traditional fossil fuel boilers, the First Minister told The Scotsman that using hydrogen for heating was “a new prospect” and “a really exciting opportunity”.

However, the Existing Homes Alliance has pointed to “repeated research” which shows that hydrogen “makes no sense for domestic heating”.

Gillian Campbell, co-director of the group, which includes Changeworks, WWF Scotland, Scottish Renewables, SNIPEF and others, said the heating method is “expensive, inefficient, and untested”.

“Heating homes with green hydrogen would use approximately six times more renewable energy than heat pumps,” said Campbell. “Just last week the Climate Change Committee said in its Seventh Climate Budget that it sees no role for hydrogen in heating buildings.”

She added: “Even the Scottish Government’s own Scientific Advisory Group said that ‘care is needed to avoid the risk that discussion about hydrogen for heating acts as a distraction from the urgent work of upgrading building stock to retain warmth, as well as developing efficient community heat schemes and district heat networks, and stand-alone electric heating’.

“It’s time to stop being distracted by the prospect of hydrogen for heating and focus on tried and tested solutions. Heat pumps and heat networks are proven technologies that can deliver clean, safe and affordable heating. Homeowners, landlords and businesses urgently need some clarity on this, with a Heat in Buildings Bill setting out clear expectations, including what is and is not a viable, safe and affordable heating option.

“The Scottish Government was clear in its draft Energy Strategy and Just Transition Plan that they do not consider that hydrogen will play a central role in heating buildings, and we will be seeking reassurance from the Scottish Government that they are not proposing to change this position.”

The Plumbing and Heating Federation, the operating name of the Scottish and Northern Ireland Plumbing Employers’ Federation (SNIPEF), called on policymakers to fast-track proven low-carbon options such as heat pumps, heat networks and comprehensive building upgrades.

Scott Sanford, technical and skills Manager at the Federation, said: “Extensive evidence shows that hydrogen is neither cost-effective nor efficient for domestic heating, and it remains largely untested in that context.

“Even the Climate Change Committee suggests hydrogen’s role is primarily in industries where there are few or no alternatives, such as chemicals, cement and certain power-generation segments that rely on Carbon Capture and Storage.

“That leaves little room for its use in heating our homes, especially given that producing green hydrogen typically requires more renewable energy than heat pumps. Instead of diverting resources into speculative hydrogen heating schemes, we should focus on proven, readily deployable options like heat pumps, heat networks, and building upgrades.

“Homeowners, landlords and businesses need clarity and confidence about which technologies are truly safe, affordable, and effective as we transition to low-carbon heating.”