A new report from the Carbon Trust, ‘Heat pump retrofit in London’, shows how heat pumps will have a critical role in tackling emissions from London’s buildings and delivering the Mayor’s 2030 net zero ambitions.

The report, commissioned by the Mayor of London, includes detailed analysis of the potential to retrofit heat pumps across a range of existing buildings in London and recommends an action plan for scaling up energy efficiency and heat pump retrofit across the capital. The report will help guide local authorities, social housing providers and others considering a heat pump retrofit, highlighting the principles of good practice system design.

Decarbonising heat is London’s biggest challenge to achieving net zero emissions. Natural gas, used mainly for heating buildings and water, accounts for 37% of all greenhouse gas emissions in London. To achieve the Mayor’s net zero target by 2030, London will need to make a rapid transition from gas to low carbon heat solutions, the majority of which will be retrofitted into existing buildings, as at least 80% of buildings are expected to still be standing in 2050.

Heat pump systems have the potential to deliver immediate carbon emission savings of 60-70% compared to conventional electric heating and 55-65% when compared to an efficient gas boiler. As the grid decarbonises further in coming decades these carbon savings are expected to increase to 90-100% of carbon emissions by 2050.

However, heat pumps are not a like-for-like replacement for gas boilers and good practice system design will be essential to their effective deployment. The report contains guidance for building owners on the technical options for installation and the principles of good practice system design in heat pump retrofit.

Additionally, a prerequisite for the roll out of heat pumps in many buildings will be improved thermal energy efficiency, which is likely to require significant investment from central government, alongside investment and co-ordination with local authorities and the private sector. Retrofitting energy efficiency measures, combined with heat pumps, provides multiple benefits including reducing energy bills, and enabling the heat pump to operate more efficiently.

Heat pumps also allow building occupants to flex their heat demand in response to tariff price signals and other payments for demand side response. The report finds that engaging in demand side response and flexibility markets is hugely beneficial to the financial case for heat pump retrofit, as well as enabling overall grid resilience.

The report concludes that most building types will require further financial support to transition from gas boilers. However, some building types, such as electrically heated blocks of flats and buildings that are due for major upgrades to the building fabric or heating systems, already have strong financial cases for heat pumps, and should be prioritised for retrofit and energy efficiency investment.

Shirley Rodrigues, Deputy Mayor for Environment and Energy, Greater London Authority, commented:
“Retrofitting heat pumps and improving the energy efficiency of existing buildings are key to achieving the Mayor’s ambitious target for London to reach net zero carbon by 2030. Not only will retrofitting heat pumps help support jobs and skills vital to a green, fair and prosperous COVID-recovery, they also reduce energy bills if designed well. However, delivering this at the scale needed will require the Government to step up investment and implement strong supportive policies.”

Tom Delay, Chief Executive, the Carbon Trust, said:
“Buildings and heat have been identified by the Committee on Climate Change as key challenge areas for decarbonisation in the coming decades, and so the analysis and recommendations detailed in the report to promote low carbon solutions that are available now is very timely. As always, heat pumps are not a silver bullet solution, which is why we have provided a suite of policy recommendations, including investment in energy efficiency in buildings and flexibility in the energy system.”

London’s Boroughs were closely involved in the research, contributing their data on buildings. One such Borough was Camden.

Commenting on the report Adam Harrison, Councillor and Cabinet member for a Sustainable Camden, London Borough of Camden, said:
“Camden supports the key findings from the ‘Heat pump retrofit in London’ study and the analysis of the costs and benefits of installing heat pumps for different building archetypes across London, whilst protecting the heating costs of residents. The findings from this study and wider support from the Greater London Authority’s Energy for Londoners programme will help to inform Camden’s retrofit policies and programmes on our journey to becoming a zero carbon Borough.”