Homes first: closing the retrofit gap

The energy required to heat homes contributes significantly to household emissions As the UK has some of the oldest housing stock in the world, our homes lose heat easily and ultimately require more energy to keep warm. Upgrading existing homes is therefore essential to address thermal inefficiencies and meet household emissions reduction targets.

What is retrofitting and why is it necessary?

‘Retrofitting’ includes both measures to make properties more thermally efficient (to reduce energy use) and to decarbonise sources of heat. Efficiency measures include window upgrades and loft, cavity or solid wall insulation, while decarbonisation technologies include heat pumps, battery storage and photovoltaic and thermal solar panels.

In some densely populated areas and for some forms of collective housing, like flats, heating provided via collective heat networks offers both efficiency and decarbonisation benefits. Heating and hot water can be supplied by centralised generation sources, such as heat pumps, geothermal energy or industrial waste heat. This can reduce fuel costs, manage peak demand and minimise the need for grid upgrades. But for most suburban homes in the West of England, connecting to district heat systems will be impossible, impractical or financially unviable. In such cases, individual retrofitting is required.

The ambition-delivery gap

In 2022, the West of England set a target to improve the energy efficiency of 250,000 homes in the region. This formed part of WECA's ambition to reach net zero by 2030 (WECA, 2024a). To meet this target, around 32,500 retrofits would have been needed each year (WECA, 2022).

But baseline assessments indicate a current annual delivery capacity of approximately 1,700 homes (ADEPT, 2022). This represents a 'delivery gap' of 19-fold magnitude between current installation rates and those required to meet the 2030 target. More recent evidence from the local authorities and independent monitoring suggests that delivery has not increased to the level needed to meet the target and, as a result, the gap has likely widened to between 20- and 40-fold.

Understanding the ambition-delivery gap

There are several reasons for the gap between ambition and reality. There is a lack of demand for and confidence in retrofitted systems amongst householders. At the same time, there are not enough skilled workers or companies to provide the products and services needed. There is also insufficient financing to help homeowners pay for upgrades or for businesses to invest in retrofitting systems.

To take one example, the workforce for solid wall insulation would need to expand 48-fold to meet the 2030 target (WECA, 2021). At 2021 installation rates, it would take 557 years to complete all the solid wall insulation needed (ibid). This is one of the most complex retrofit measures, so it is being delivered more slowly than other types of home improvements, but labour shortages and insufficient capacity can be found across retrofit trade services.

Governance and asymmetric delivery

Beyond the region-wide aspiration to improve the energy efficiency of 250,000 homes, unitary authorities are responsible for target-setting. This results in significant regional divergence. Bath and North East Somerset Council (BANES) has set a target for 65,000 retrofits and a 40% phase-out of gas heating by 2030 (BANES, 2023). Similarly, Bristol City Council has set a requirement to replace 160,000 boilers (Bristol City Council, 2024). Conversely, South Gloucestershire and North Somerset lack quantified targets for retrofitting the existing housing stock, focusing instead on new-build standards (South Gloucestershire Council, 2023; North Somerset Council, 2023).

Within the West of England, there is no shortage of projects attempting to address the knotty issue of increasing retrofitting rates. Bristol has launched the ‘City Leap Energy Partnership’, a joint venture with the private sector designed to attract £1 billion of investment into low-carbon infrastructure (Bristol City Council, 2024). Meanwhile, BANES operates the ‘Energy at Home’ scheme, which offers unconditional loans to homeowners for energy improvements (Livewell BANES, 2024). WECA acts as a strategic enabler, managing the £10 million ‘Retrofit West’ accelerator programme to address skills and minimise barriers (WECA 2024b).

Progress – happening, but slowly

Since the inception of Retrofit West in 2022, strides have been made in building the infrastructure required. The accelerator programme was established with WECA funding as a Community Interest Company by the Centre for Sustainable Energy (CSE). Active since 2023, it has become one of the UK’s few examples of a coordinated local retrofit one-stop-shop, connecting homeowners with independent advice and vetted installers while developing a thriving local supply chain (CSE, 2025). An independent evaluation commissioned by WECA found that businesses on the Retrofit West installer hub reported a 43% increase in inquiries for their services and a 31% increase in completed retrofit jobs (ibid).

In Bath and North East Somerset, the proportion of homes achieving an energy performance certificates (EPC) rating of Band C or above rose from 19% in 2023 to 36% by 2025 – driven primarily by Social Housing Decarbonisation Fund investment – though private homes lag considerably with just 22% reaching Band C (Inside Housing, 2025). While these are encouraging indicators of growing market activity, the absolute scale of delivery remains a fraction of what the 2030 target demands.

Outside of individual success stories, problems persist. There is no unified regional dashboard to monitor overall retrofit numbers and proxy metrics suggest only incremental gains. For example, South Gloucestershire reported a rise in homes with EPC rated A-C of just one percentage point between 2023 and 2024 (South Gloucestershire Council, 2024). Meanwhile, North Somerset Council has formally admitted that the authority is "not on course to meet our target of being net zero by 2030" (North Somerset Council, 2025).

Insufficient monitoring remains a significant obstacle. EPC-based figures do not capture the 50% of homes that are neither being sold nor rented. Improved monitoring and evaluation of the multiple initiatives in the region will allow for better coordination and learning.

Conclusion

The most recent regional assessment shows a baseline retrofit capacity one-nineteenth of the rate needed to meet WECA’s 2030 target. There hasn’t been any published evidence of step change improvements since the retrofit accelerator launched in 2022, suggesting that the gap is unlikely to have closed.

Despite many initiatives, pilots and projects, current retrofit delivery rates are still too low to meet the region’s 2030 ambition. It’s probable that the gap between the ambition and reality of retrofitting rates in the region may now be between 20- and 40-fold.

There is significant room to improve how projects are monitored and evaluated. Learning from these could improve how future projects are designed and coordinated. Insufficient supply and demand of retrofitting-related products and services must also be addressed. This includes not only increasing rates of adoption, but also changes to the workforce structure, ensuring that a sufficient number of tradespeople and businesses are equipped to install retrofit technologies.

References

Bristol Heat Network policy insight

ADEPT. (2022). Case Study: Levelling Up. West of England Combined Authority. Action on home energy efficiency. London: ADEPT. Available at: https://www.adeptnet.org.uk/sites/default/files/media/2022-12/CS%20WECA%20Retroftting.pdf. Accessed 24.11.2025.

Bath & North East Somerset Council. (2023). Bath & North East Somerset Climate Emergency Strategy. Bath: Bath & North East Somerset Council. Available at: https://www.bathns.gov.uk/sites/default/files/2023-03/BANES%20Climate%20Emergency%20Strategy%20Document%20AW1.pdf. Accessed 24.11.2025.

Bristol City Council. (2024). Our climate action on buildings [online]. Bristol: Bristol City Council. Available at: https://www.bristol.gov.uk/council/policies-plans-and-strategies/our-action-on-climate-and-ecology/our-climate-action-on-buildings Accessed 24.11.2025.

Centre for Sustainable Energy. (2025). Retrofit West [online]. Bristol: Centre for Sustainable Energy. Available at: https://www.cse.org.uk/retrofit-west/ Accessed 06.03.2026.

Inside Housing. (2025). Bath and North East Somerset: what declaring an ecological as well as a climate emergency means for housing [online]. Available at: https://www.insidehousing.co.uk/home/bath-and-north-east-somerset-what-declaring-an-ecological-as-well-as-a-climate-emergency-means-for-delivery-and-existing-homes-94870. Accessed 06.03.2026.

Livewell B&NES. (2024). Apply for a Home Energy Loan [online]. Bath: Bath & North East Somerset Council. Available at: https://www.bathns.gov.uk/apply-home-energy-loan. Accessed 24.11.2025.

North Somerset Council. (2023). Climate Emergency Action Plan [online]. North Somerset: North Somerset Council. Available at: https://www.n-somerset.gov.uk/sites/default/files/2023-03/31208%20Climate%20Emergency%20Action%20Plan%20ACC.pdf. Accessed 24.11.2025.

North Somerset Council. (2025). Significant progress made reducing North Somerset carbon emissions [online]. North Somerset: North Somerset Council. Available at: https://n-somerset.gov.uk/news/significant-progress-made-reducing-north-somerset-carbon-emissions. Accessed 06.03.2026.

South Gloucestershire Council. (2023). Housing Strategy 2023 [online]. South Gloucestershire: South Gloucestershire Council. Available at: https://beta.southglos.gov.uk/static/b9bd2fd683fab16884d2ba8fffbeb490/Housing_Strategy_2023_download.pdf. Accessed 24.11.2025.

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West of England Combined Mayoral Authority. (2021). WECA Green Jobs and Skills Retrofit Report [online]. Bristol: West of England Combined Authority. Available from: https://www.westofengland-ca.gov.uk/wp-content/uploads/2021/07/WECA_Green-Jobs-and-Skills_Retrofit_Report-1_Final_01_06_2021.pdf. Accessed 24.11.2025.

West of England Combined Mayoral Authority. (2022). Retrofit Accelerator Full Business Case [online]. Bristol: West of England Combined Authority. Available at: https://www.westofengland-ca.gov.uk/wp-content/uploads/2022/09/Retrofit-Accelerator-F-ull-Business-Case.pdf. Accessed 24.11.2025.

West of England Combined Mayoral Authority. (2024a). Retrofit projects across the West of England [online]. Bristol: West of England Combined Authority. Available at: https://www.westofengland-ca.gov.uk/what-we-do/environment/retrofit-sustainable-buildings-and-places/retrofit-projects-across-the-west-of-england/. Accessed 24.11.2025.

West of England Combined Mayoral Authority. (2024b). Retrofit West Advice Service [online]. Bristol: West of England Combined Authority. Available at: https://www.westofengland-ca.gov.uk/what-we-do/environment/retrofit-west-advice-service/. Accessed 24.11.2025.