A new report from the Carbon Trust says 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.
The Carbon Trust says 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.
