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Development of trajectories for residential heat decarbonisation to inform the Sixth Carbon Budget (Element Energy)

1. Outline

The Climate Change Committee (CCC) commissioned Element Energy to carry out research on decarbonisation pathways for space heating and hot water demand in existing UK homes. Five pathways were developed in total, all seeking to achieve full decarbonisation of heat in existing homes by 2050 at the latest. Particular analytical focus was placed on the Sixth Carbon Budget period between the years of 2033 and 2037, with a view to informing the CCC’s Sixth Carbon Budget advice to Government.

The research is underpinned by a comprehensive update of assumptions, incorporating the latest evidence on the costs associated with energy efficiency and low-carbon heat, and including energy efficiency savings assumptions based on data from the National Energy Efficiency Data-framework (NEED).

In December 2020 the Executive Summary of Element Energy’s report was published. As of April 2021, the full report detailing Element Energy’s research was published in addition.

2. Key recommendations

The research found that:

  • Decarbonisation of heating for the UK existing housing stock is possible, and can be achieved with average net investment of less than £10,000 per home. By 2035, the Balanced Pathway cuts direct emissions from existing homes to around half today’s levels.
  • The Balanced Pathway includes 10.8 million loft insulation measures, 3.4 million solid wall insulation measures and 3.1 million cavity wall insulation measures by 2050. Around 65% of energy efficiency deployment in existing homes in the Balanced Pathway has been installed by 2030 – urgent ramp-up is needed relative to deployment levels today to achieve this. The installation rates for insulation measures such as lofts and cavity walls are within the range previously achieved under the supplier obligations in the early 2010s. Solid wall installation rates are more ambitious but considered achievable with strong policy in our testing with stakeholders.
  • The scenarios include a low-carbon heating system for every home. The Balanced Pathway includes low-carbon district heat for 5.5m existing homes, heat pumps for 21m existing homes (including 5m in a hybrid configuration, with some using hydrogen as a back-up) and direct electric heating for around 2m existing homes. There remains a high level of optionality around the exact mix of heating systems deployed to abate emissions from homes, although all scenarios point to the importance of delivering significant increases in heat pump deployment over the 2020s, deploying heat networks in areas where they are suitable, and progressing hydrogen trials.

3. Supporting data

As of April 2021, an updated version of the assumptions log for this work has been published. Updates are limited to the ‘Fuel costs and CO2’ tab only and include corrections to the costs of low carbon heat networks, and biomass emissions, as well as improved labelling and streamlining to include only those assumptions used in modelling.