How expensive are heat pumps? A brief look at the clean technology taking off in Europe

You’ve probably heard of heat pumps by now - devices that take energy from the air, ground and water and transform it into heat or cool air. But how, when and where do they work exactly?

Given the urgency of the energy transition, it’s understandable that discussions about which renewable solutions are best can get rather… heated. And chances are you’ll have first encountered heat pumps in a positive or negative light before getting to grips with the basics.

More and more people are installing the technology. Last year, heat pumps helped Europe to save 8 million tonnes of CO2 emissions, as 3 million units replaced around 4 billion cubic metres of fossil gas - so there’s definitely big potential.

If you’re thinking of becoming a heat pump owner, here are some things you ought to know.

Air, water and ground heat pumps work by taking energy from these sources and turning it into heat or cold air. They do this within the ‘refrigerant cycle’ - with its four phases of evaporation, compression, condensation and expansion, the European Heat Pump Association (EPHA) explains.

Essentially, the collected heat is used to turn the refrigerant fluid in the pump’s heat exchanger into gas, which is then concentrated to a high pressure in the compressor, prompting a rise in temperature. Extra energy is needed to run this bit of the machinery - ideally from green electricity, which would make the whole process carbon neutral.

The hot and highly pressurised vapour then passes through the second heat exchanger, known as the condenser. This is where the refrigerant discharges heat into the home’s heating system - be it a water-based system like radiators or underfloor heating, or an air conditioning unit.

Releasing its heat returns the refrigerant