After 250,000 installations across the UK, we look at the devices central to Labour’s vision of a ‘home upgrade revolution’

Heating the UK’s 28m homes creates almost a fifth of the country’s greenhouse gas emissions, so after decades of relying on gas and oil boilers, households will need to break their addiction to fossil fuels if the government hopes to meet its climate targets.

For most homes, the alternative to traditional heating systems is likely to be an electric air source heat pump.