A report backed by the four gas distribution networks (GDN) has claimed that heat pumps would be impractical for between 37 and 54 per cent of UK homes currently using gas.

The report, published by the Energy & Utilities Alliance (EUA) in partnership with the GDNs and Leeds Beckett University, says a “mosaic” of low-carbon heating technologies, including a hydrogen network, will be required to reach net zero by 2050.

Its analysis of 22.7 million properties highlights “limiting factors” to installing heat pumps in eight to 12 million of these. They include homes built with solid brick walls, uninsulated and/or space constrained such as flats and mid-terrace buildings, as well as high rise buildings.

It says that a further four million homes (equivalent to 18 per cent of the total) could be made suitable for heat pump retrofit through energy efficiency measures such as cavity wall insulation. However, it suggests that the resultant disruption to the customer and cost of upgrading the electricity distribution network “mean these properties may be better served through gas-based technology and a decarbonised gas network”.

It recommends further analysis should be undertaken to consider the internal system changes needed for heat pumps and hydrogen boilers. This includes the suitability of radiators for the low-carbon transition, and potential changes to hot water cylinders should combi-boilers be replaced with heat pumps.

The report accepts that heat pumps will “play a vital role in the UK’s net zero transition” and cites a figure of seven to 10 million homes where there are no limiting factors to installation. However, it adds that “for existing UK housing stock, levels of disruption and association costs as well as lack of available space mean heat pumps will be an optimal solution for a minority of properties”.

The report recommends their use is supported by a decarbonised gas network carrying a gas such as hydrogen, zero carbon at the point of use.

EUA chairman Mike Foster said: “Heat pumps will play a key role in the future of heat, however it’s important to recognise that for them to work effectively as the sole heating source, the building needs to be thermally efficient, and they require internal and external space as well as changes to internal systems such as radiators.

“Levels of disruption to people in their homes and associated costs mean heat pumps will be a solution for a minority of properties only, so hydrogen, biogas and hybrid systems need to play a significant role in the decarbonisation of heat in order to support our 2050 net zero ambition.

“This analysis shows a house-by-house heating solution is needed, and any thoughts to carve up the UK and force regional solutions upon consumers will be doomed to fail.”

Tim Harwood, H21 programme director at Northern Gas Networks, said: “Decarbonising heat is arguably the biggest challenge we face in the drive to reduce the UK’s carbon emissions, and heat fulfils some of our most basic needs – to provide warmth, cook food and heat water.

“Switching to low carbon heat is likely in many instances to require changes to appliances within our homes and offices, as well as the building itself. When we take these points into consideration, we need an approach that focuses on investment and people’s experience of heating technologies in equal measure as customers need to be part of this journey.

“Different heating technology solutions are going to be applicable to different property types depending on the age, and profile of the building, and the capacity of energy networks.”