How green is heating with a heat pump?

CO2 emissions of various types of heating

Heat pumps are powered by electricity, so just how sustainable a heat pump heating system is very much depends on where that electricity is coming from. But even just plugged into the UK's national grid a heat pump produces >4 times less CO2 than gas heating, and 6.6 times less CO2 than heating with oil.

Plugged into a renewable electricity supply and heat pumps are 116 times better than gas, and 165 times better than oil heating!

So if you are installing a heat pump then definitely also switch to a 100% renewable electricity supply.

The emission factors here are from SAP 2019, National Grid ESO, and Carbonbrief. The heat pump COP (efficiency) assumed for the calculation is 3. So for every kWh of electricity this heat pump would, on average, provide 3 kWh of heat.

You can also see there's a distinctly renewable end to the graph - heat pumps and biomass beat gas and oil hands down when it comes to impact on climate change. Below are the figures that the graph is drawn from, as well as the sources of information used.

Heating Typekg CO2/kWh
COP 3 Heat pump, powered renewably0.002
Renewable electricity0.006
Wood chips0.026From SAP 2019
Wood logs0.035From SAP 2019
Wood pellets0.059From SAP 2019
COP 3 Heat pump, powered by the national grid0.072
National grid electricity0.215
Mains gas0.233From SAP 2019
Bulk LPG0.267From SAP 2019
Heating oil0.331From SAP 2019
Anthracite coal0.494From SAP 2019