Retrofit First: A Guide for Developers and Project Managers

About the author

Ian Poole is an Associate Director in Elliott Wood’s sustainability team and has direct experience shaping Westminster’s Retrofit First policy.

While at Elliott Wood, Ian spent 18 months seconded to Westminster City Council as a sustainability officer in the Town Planning team. During that time, he co-authored Policy 43: Retrofit First and its supporting guidance, helping to develop the policy after initial consultation, strengthen the evidence base and defend it through examination.

This guide draws on Ian’s direct experience shaping the policy, combined with his consultancy work at Elliott Wood supporting developers, project managers and design teams on whole-life carbon, retrofit strategy, circular economy and planning risk.

Ian is also a member of the RBKC Quality Review Panel and has contributed to several industry groups, including the UK Net Zero Carbon Buildings Standard Embodied Carbon Task Group, Structural Engineers Declare steering group and the IStructE Sustainability Panel.

What is Retrofit First?

Retrofit First is a planning approach that asks project teams to start with the existing building before considering demolition.

It means asking: can we retain, adapt, extend or improve what is already there, rather than demolishing and starting again?

The policy does not ban demolition, but it does change the burden of proof. If a project involves substantial demolition, applicants need to show that retrofit has been properly explored and that demolition is necessary, justified and supported by evidence.

For Westminster, this is now embedded in planning policy. That matters because Westminster is highly influential and is often seen as a direction setter, both nationally and internationally. It is likely that other councils will adopt similar policy, or refer to this guidance, making it best practice to use not just in Westminster, but for all developments across the UK.

How we can help

Our Retrofit First policy expertise helps clients make better decisions and manage risk earlier.

We support developers, project managers and design teams by bringing retrofit-first thinking into portfolio decisions, project strategy and the technical evidence needed for planning.

Get in touch

What it means for developers and project managers

In general, if more demolition is proposed, more evidence is required.

For developers and project managers, this means retrofit needs to be considered early. It should shape the brief, the design strategy, the planning route, the carbon assessment and the public-benefit case.

The policy defines retrofit and the different levels of intervention depending on how much of the existing building is removed. Terms such as retrofit, deep retrofit and new build are widely used, but they can be interpreted differently across projects. The policy makes this terminology more specific by linking it to measurable levels of demolition and corresponding planning requirements.

However, Retrofit First is not only about restricting demolition.

Westminster’s policy recognises retention can create design, heritage, servicing or floorplate challenges. Where changes or extensions are needed to make retrofit viable, the planning balance gives significant weight to retaining the existing building.

Can demolition be justified?

Where substantial demolition is proposed, applicants must prepare a pre-redevelopment audit.

This is the evidence document that sets out the sequential test and explains why demolition is necessary. The test works step by step.

It looks at the following considerations in order:

Structural soundness
Whether the existing building can support the required use
Whether retrofit would create more whole-life carbon than new build
Whether any additional public benefits justify the impact of demolition.

Applicants only progress as far as needed to make the case. The sequential test is explained below.

The sequential test

Test 1

Is the building structurally sound?

If the building is unsafe, or cannot viably be made safe, demolition may be justified. But this is expected to be rare.

The structural case must be factual and independent of the preferred development proposal. Wanting to add extra storeys, for example, is not the same as proving the existing structure is unsound.

Test 2

Can the existing building support the required use?

Some sites may need to deliver a specific planning priority, such as affordable homes, community infrastructure or another strategic use. If the existing building cannot reasonably support that use, demolition may be justified.

Test 3

Would retrofit create more whole-life carbon than new build?

This is rare, but possible, particularly where retrofit requires extensive strengthening, temporary works, foundations or servicing upgrades. The evidence must be robust, and the options must be genuinely comparable.

Test 4

Are the public benefits strong enough?

Where new build creates additional carbon and environmental harm, the applicant must show the additional public benefits are substantial enough to justify it and additional to what could be provided through retrofitting.

Actions for developers

Define retention as the starting point, not a late-stage option. Ask the team to identify how much of the existing building can be retained, adapted or extended before a demolition-led strategy is pursued.

Bring structural, sustainability and planning input together early. The viability of retention, the whole-life carbon case and the planning route are now interdependent.

Before progressing a new-build strategy, assess whether the sequential test can realistically be passed. If the building is structurally sound and retrofit options are credible, demolition may carry significant risk.

Move beyond generic economic benefits. Identify social, environmental and economic benefits that are specific to the proposed scheme and could not be delivered through a retrofit option.

Look for opportunities to retain, reuse or recover materials in high-value applications. Westminster’s deconstruction circularity metric considers not only carbon, but also the value already invested in existing materials and how much of that value is retained, reused or wasted.

Circularity can therefore strengthen the planning and public-benefit case, reduce waste and support a more compelling sustainability narrative.

Briefing 1 — Developers and project managers attend a Retrofit First breakfast briefing with Elliott Wood

Actions for project managers

Do not treat retrofit appraisal as a side exercise. Build time into the programme for retention studies, structural testing, carbon optioneering and design iteration.

Make sure the structural report, Whole Life Carbon Assessment, Circular Economy statement, pre-redevelopment audit, sequential test evidence and public-benefit case are aligned. Gaps between these documents can create planning risk.

If a retrofit option looks like a new-build scheme forced onto an existing structure, it is unlikely to be credible. Push the team to test options that genuinely start from the existing building.

Create a clear audit trail showing how each major design decision relates to structure, use, carbon, public benefit and circularity. This will make the planning case stronger and easier to defend.

Treat unjustified demolition as a core risk to cost, programme and consent. Where partial or substantial demolition is proposed, make sure deconstruction audit requirements are built into the programme at planning, pre-commencement and post-completion stages.

Saving time and costs with BEAM

Working early with BEAM at 33 Cavendish Square, we helped their one-million sq ft development achieve unanimous planning consent just eight months after the first pre-application meeting, saving time and cost during the early-stage programme.

Our input is also helping retain 58% of the existing structure.

We used our expert knowledge of the retrofit-first policy and planning landscape to enable the project team to maximise retention and introduce an innovative vaulted slab system to meet policy requirements and add value to the project.

Our services included:

Attending pre-apps and advising the planning consultant to navigate early-stage discussions with the planning officers
Working with the sustainability consultant to embed the strategy for the project, setting requirements for the design team
Being a third-party reviewer of the sustainability reports and assessments
Attending key client and design team meetings, supporting the team to bring innovative solutions into the project

Quote

We had to balance the need to meet the upfront carbon target, which was a key planning policy requirement, with the need to create a building that would attract high-quality long-term tenants.

Peter Pulford
Director and Head of Development, BEAM

How we can help

Our Retrofit First policy expertise helps clients make better decisions and manage risk earlier.

Early collaboration ensures our expertise is applied before the solution has been fixed, helping develop responses that manage risk and create greater value and impact.