To ask the Secretary of State for Environment, Food and Rural Affairs what assessment he has made of the potential effect on carbon dioxide emissions of commercial and residential buildings adopting heat pump technology in place of gas boilers. (150214)

The Federation of Environmental Trade Associations (FETA) has confirmed that 200,000 heat pumps were sold in the commercial sector in 2006, of which around 90 per cent. were air source.

Estimates for the costs and savings in the housing market have been made for the Carbon Emissions Reduction Target (CERT). Ground source heat pumps are not currently a cost-effective substitute for gas condensing boilers. In a typical three bed-roomed semi-detached house, carbon dioxide (CO₂) savings are around 0.46 tonnes CO₂ each year.

However, if they replace conventional electric heating, they are cost-effective, with annual CO₂ savings of around 4.3 tonnes CO₂ each year. If they replace solid fuel stoves, they are not cost effective but save around 5.7 tonnes CO₂ each year. By comparison, cavity wall insulation would save 0.575 tonnes CO₂ each year in a gas condensing boiler-heated house.

If 10 million homes with gas condensing boilers had them replaced with ground source heat pumps, national savings would be around 4.6 MtCO₂ (million tonnes of CO₂) each year. This compares with the impact of all the policies in the Climate Change Programme by 2010, of 17.6 MtCO₂ each year.