How Westminster reframed the retrofit conversation
29.07.2025
Written by Ian Poole
Associate Director, Innovation Lead & Environment Steward
The development of a clear policy to support the retention and retrofit of existing buildings not protected by listing was a priority when Westminster City Council began revising its City Plan in 2022. For a borough that declared a climate emergency in 2019, the absence of such a policy sat awkwardly with its commitment to reducing carbon emissions and construction waste. A response was overdue.
Policy 43, more commonly known as the ‘Retrofit First’ policy, aims to promote and accelerate the retrofitting of existing buildings and reduce the level of demolition in the borough. Following years of development, the policy is expected to be formally adopted by the end of 2025.
For property professionals, this marks a significant shift. Developers will now be expected to design with reuse in mind, and planning officers will have a clear policy framework which favours retention over wholesale redevelopment.
Associate Director Ian Poole spent 18 months on secondment at Westminster City Council, working with planning teams to address development-related environmental impacts. The article below, originally published in Estates Gazette, covers his work on the Council's Retrofit First policy.
Waste not, want not
Construction and demolition waste account for over 50% of all waste in the UK. Most of that material has low or no residual value and ends up in landfill.
Meanwhile, replacing these lost resources means extracting new ones: sand dredged from the seabed, stone quarried from national parks, imported timber and bricks. It’s a model that’s both economically and environmentally unsustainable.
The Retrofit First policy seeks to reverse that logic; to make better use of what already exists, cut down on waste and rethink what ‘development’ looks like.
Policy 43, as proposed, has three key parts: stating that retrofit should be considered first; setting upfront carbon targets for all major developments; and stating that significant weight will be given in the planning balance to securing the retention of buildings.
In essence, developers must now demonstrate why demolition is necessary, rather than it being the default assumption.
Retrofit reclassified
One of the biggest challenges in developing the policy was defining what constitutes retrofit. Most definitions state, or allude to, the fact that retrofits should improve energy performance and retain the majority of the building fabric. The former is easy to define, as we already have means of measuring energy performance, but how do we measure retention? And what is the majority?
It was concluded that 50% of the existing floor area must be retained to be classed as a retrofit. Greater than this is considered ‘substantial demolition’.
Recognising that retrofit won’t always be viable, the policy includes a four-stage “sequential test” to guide applicants. Demolition may be considered acceptable only if one of the following can be evidenced:
— The existing structure is unsafe.— Specific build use classes are needed, which the existing building cannot support.
— A whole-life carbon assessment proves demolition has a lower impact than retrofit.
— Additional public benefits justify the additional carbon associated with substantial demolition.
The sequential test requires applicants to sequentially move through the options until they reach one that provides sufficient reason to apply for substantial demolition. This must be evidenced through a third- party reviewed pre-redevelopment audit.
Only in Westminster
Though not yet formally adopted, the policy is already reshaping design thinking in Westminster. Developers are increasingly incorporating retention strategies and preliminary planning data shows a trend toward higher retention rates and falling carbon impacts year on year.
As one developer commented at a recent industry event: “This development could only have happened in Westminster.”
Will tighter requirements drive investment elsewhere? Some argue that restrictive policy risks making Westminster less competitive. But the growing demand for sustainable buildings suggests the opposite may prove true. Retrofit is fast becoming a mark of distinction.
But for the Retrofit First policy to have systemic impact it needs to be adopted at scale. We hope that the work Westminster City Council has done will make it easier and less resource intensive for some of the 300 councils across England to develop similar policies. Regional or national policy will be key to ensuring consistency and broader market alignment.
We need new methods of understanding the ‘value’ of an existing building and all the materials within it. The Retrofit First policy reframes the conversation. It’s not about nostalgia or obstruction, but designing smarter, building leaner and valuing what we already have.
