Patrick Harvie’s heat pump plans are nothing more than hot air - Susan Dalgety

Patrick Harvie, co-leader of the Scottish Green party, evangelical cyclist and the government minister responsible for green zero carbon buildings, is about to make himself the most unpopular man in Scotland.

Heat pumps can be very expensive to run as they use a lot of electricity, and they cost several times more than an average boiler to buy, says Susan Dalgety (Photo by Leon Neal/Getty Images)

He has just published a consultation paper on plans to overhaul the energy performance certificate (EPC) ratings for homes, an essential document for the sale of any dwelling.

At the moment, the certificate shows how much energy a home uses and provides a rough estimate of how much it costs to heat it. You cannot sell a house or flat without one.

But Harvie wants to go further. He wants the EPC ratings to also include the type of heating system used in a home, which on the face of it seems very sensible. Unfortunately, the minister also wants the rating for gas boilers to be downgraded, forcing people to ditch their gas-fired heating systems if and when they want to sell their home.

If Patrick Harvie gets his way, households will have to replace their boilers with either all-electric heating or an air-source heat pump – a large machine attached to the outside of a house. Heat pumps work by extracting warm air from outside (good luck with that in Edinburgh), using it to heat and power a home. They are powered by electricity, so have less impact on the environment than a gas boiler. But they work less efficiently in homes that are not completely insulated, they can be very expensive to run as they use a lot of electricity, and they cost several times more than an average boiler to buy. Installing a pump can cost as much as £10,000.

Then there is the small matter of tenements. It may have slipped Harvie’s notice, but there are more than half a million tenement flats in Scotland. They are the most common type of dwelling in urban areas – and I am quoting the Scottish government here – accounting for 28 per cent of urban homes.

I love living in my tenement flat in Viewforth, but it is draughty and hard to heat. And there is nowhere to put an air-source heat pump, unless our stair is to have eight of them hanging off the back of our building, a very unlikely scenario.

We are now all very much aware of the damage climate change is doing to our planet. Most of us accept that we need to significantly reduce our use of fossil fuels, but governments, not matter how zealous, cannot bring about sustainable change without the consent of the people.

Harvie’s plans to penalise those of us who use gas boilers by making it impossible to sell our homes unless we change our heating systems may have seemed like a good idea when discussed on a Zoom meeting, but this is real life.

The minister insists that if the government is to meet its 2030 net zero targets, more than one million Scottish homes will need to change to “a climate friendly heating system”.

What he doesn’t explain is how those one million households are going to be able to afford to make the switch, or if it is even possible in such a short timescale. Until he does, his plans are nothing more than hot air.