Image: Carbon Trust

Heat pumps retrofitted to office and residential buildings across London could support achievement of the city’s 2030 carbon net zero target, the Carbon Trust has reported.

A new report, commissioned by the Mayor of London, indicates that heat pump systems have the potential to deliver immediate carbon emission savings. These could reach 60-70% compared to conventional electric heating and 55-65% when compared to an efficient gas boiler. These savings are expected to increase to 90-100% of carbon emissions as the grid decarbonises further up to 2050.

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Decarbonising heat is the biggest challenge to achieving net zero emissions in London as well as nationally in the UK. Natural gas, used mainly for heating buildings and water, accounts for 37% of the greenhouse gas emissions in London. A rapid transition from gas to low carbon heat solutions is needed to achieve the Mayor’s net zero target by 2030.

The majority of these must be retrofitted into existing buildings. At least 80% of the buildings are expected to still be standing in 2050.

Earlier analysis indicated that heat pump installations in London should reach 120,000/year by 2030. However, under the government’s Renewable Heat Incentive support programme an average of just 66 installations per year have taken place since 2014.

“Buildings and heat have been identified by the Committee on Climate Change as key challenge areas for decarbonisation in the coming decades. So the analysis and recommendations detailed in the report to promote low carbon solutions that are available now is very timely,” comments Tom Delay, Chief Executive of the Carbon Trust.

However, he cautions that heat pumps are not a “silver bullet solution” and their rollout must be accompanied with other policy actions.

Installing heat pumps

One of these is that good practice system design will be essential to the effective deployment of heat pumps. They are not a like-for-like replacement for gas boilers, the report notes.

Alongside their rollout, many buildings also will need energy efficiency improvements.

All these activities will require significant investment from central government, local authorities and the private sector, the report states.

A challenge for building owners is that heat pumps have higher up-front costs than replacement gas boilers or electric heating systems. Thus they will require up-front financial support. However, particularly in the residential sector their lifetime costs are similar due to reduced energy bills and the longer up to 30-year lifetimes.

For example, for a sample of residential properties, the 30-year costs ranged from 18% lower to 127% higher than business as usual over that period.

Moreover, heat pumps can provide flexibility to network operators. This can bring further financial benefits to building owners, alongside supporting the resilience of the grid.

The report concludes that those building types for which the lifetime financial case for heat pump retrofit is already strong should be prioritised. These include electrically heated blocks of flats, buildings with a high cooling demand and buildings that already require major renovations to the fabric or their heating systems.