Heat pumps, energy efficiency and DSR ‘critical’ to decarbonise London


If London is to stand a chance become a net zero emissions city within a decade, mass deployment and funding of heat pumps will be critical, according to a new report.

The Carbon Trust’s  ‘Heat pump retrofit in London’, commissioned by the mayor’s office, also underlines the need for a simultaneous step change in building energy efficiency. That will require “significant” investment from central government, per the report.

Meanwhile, smart heat pumps that can shift loads (also known as demand-side response, or DSR) have a major impact on the business case for retrofitting heat pumps, which are more expensive and disruptive than other approaches.

The report aims to highlights key principles of good practice system design. It underlines the need for well designed and installed systems to unlock potential carbon emission savings of 60-70 per cent compared to conventional electric heating and 55-65 per cent when compared to an efficient gas boiler. These savings will increase as the grid decarbonises further.

Given the sums involved for a city-wide retrofit, the report states that most building types will require some form of grant or subsidy to remove gas boilers, but that blocks of flats on electric heating and other buildings already due for major upgrades already present “strong” business cases and should be prioritised. 

Greater London Authority deputy mayor for environment and energy, Shirley Rodrigues, said the twin-pronged approach is “key to achieving the Mayor’s ambitious target for London to reach net zero carbon by 2030” while helping the city to build a cleaner post-Covid recovery. “However, delivering this at the scale needed will require the Government to step up investment and implement strong supportive policies,” she added.

Carbon Trust chief executive, Tom Delay, said the report’s aim was to plot a path to interventions using technologies that can be delivered today. 

“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,” he said.

See the report here.


  1. Decarbonising London within 10 years is a great ambition, but unfortunately not likely to succeed, which is a pity, however aiming high is a good tactic, but if it is too high it can discredit the target. Even if it will be possible to convert all the buildings to heat pumps and a few to just electricity, and all the vehicles to electric or hydrogen power from electricity, where is the zero carbon electricity to come from? Grand ideas to decarbonise the use of power, but if the electricity comes from fossil fuels, that defeats the object. Those holding the levers of power continue to ignore the massive deficit of zero carbon energy supply which was only 7.2% of the UK energy demand in 2018 (BEIS data) which included a small amount of nuclear power.


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