Heat pumps, a technology that offers a more efficient way to keep homes warm in the winter, were seen as a key tool to help Europe ride out the spike in energy prices triggered by Russia’s 2022 invasion of Ukraine. They’re also the target of heavy subsidies from governments looking for ways to curb planet-warming emissions and mitigate global warming. Adoption has surged: Sales of heat pumps in Europe jumped to 3 million units in 2022, almost double the figure in 2020. But many hurdles remain to their wider adoption, including concerns about cost.

A heat pump is a machine that uses electricity to warm a home or other space — like a car — but doesn’t work in the same way as traditional electric heaters. Put simply, they move heat around instead of creating it, which is more efficient and less energy-intensive. Some heat pumps work by heating water, which is then pumped into radiators or underfloor heating, while others blow hot air directly into the space.