Making the retrofit first case in a planning statement

No national policy creates a presumption against demolition. What has changed is that a planning statement proposing substantial demolition now has to carry a reasoned option appraisal showing that retention and refurbishment were tested and why they were set aside. Local plans and supplementary planning documents in a growing number of authorities require it expressly, the London Plan requires whole life-cycle carbon assessment and circular economy reporting for referable schemes, and officers who have no local policy hook still ask the question. An appraisal written after the scheme is fixed reads as a justification. One written during feasibility reads as evidence.

So commission it early, and write the planning statement around its findings rather than the other way round.

Why demolition now needs a reasoned justification

Three strands converge.

The first is carbon. Demolition and rebuild releases the embodied carbon of the existing structure and incurs the upfront carbon of the new one. Assessed under BS EN 15978 and the RICS whole life carbon methodology, modules A1 to A5 capture that upfront burden, and on a structurally sound commercial building it is a large number.

The second is waste and materials policy. Circular economy requirements, strongest in London but increasingly reflected in adopted plans elsewhere, ask what proportion of the existing building is retained, what is reused in situ, what is reclaimed and what goes to recovery or landfill.

The third is design and heritage. A building need not be listed or in a conservation area to carry townscape value. Where it is a non-designated heritage asset, or appears on a local list, its loss is a harm that has to be weighed.

None of those strands says you cannot demolish. They say you have to show your working.

The comparison a council expects to see

An appraisal with two options, keep it or knock it down, does not survive scrutiny. Four or five options, tested against the same criteria, does.

Each row needs the same four columns filled in: the floorspace and use it delivers, the carbon figure, the deliverability position, and the policy objectives it meets or fails. Scoring options against different criteria, or assessing the preferred option in more detail than the others, is the flaw officers pick up on first.

Do not score the appraisal numerically unless you can defend the weightings. A narrative conclusion drawn from a consistent table is harder to attack than a weighted matrix with arbitrary multipliers.

Structural and condition evidence that supports it

The argument that a retrofit option is not feasible has to rest on investigation, not on assertion.

A structural appraisal with intrusive investigation is the core document. On a concrete-framed building that means core samples, carbonation depth, chloride content and reinforcement cover, with half-cell potential survey where corrosion is suspected. On steel frames it means connection details and fire protection condition. Record floor loadings against the proposed use, because an office frame will not take residential loading plus a new core without strengthening.

Dimensional constraints decide more cases than material condition. Floor-to-soffit height that cannot accommodate a modern services zone and a compliant finished floor level. A column grid that will not plan efficiently for the proposed use. Core positions that cannot be made compliant under Part M or under the fire strategy, with the Building Safety Act 2022 gateway regime adding its own constraints on tall residential buildings.

Deleterious materials need naming rather than gesturing at. Asbestos locations and type, reinforced autoclaved aerated concrete planks, high alumina cement, and any identified structural defect, each with the survey reference.

A refurbishment option rejected because "the building is in poor condition" will be sent back. The same option rejected because reinforcement cover averages 12 millimetres against a 30 millimetre requirement, with carbonation to the bar across three of five cores, will not.

Carbon figures and their limitations

Carbon numbers do a lot of work in these appraisals and they are more fragile than they look. Say so in the statement, because an officer who finds the caveat themselves trusts the rest of the document less.

Four limitations recur.

The boundary. Upfront carbon in modules A1 to A5 is the comparable figure. Module D benefits from future reuse and recovery sit outside most policy targets, so including them in the headline makes the comparison look better and the document look partisan.

The counterfactual. A retrofit option modelled with minimal intervention produces a low carbon figure and fails on performance, while one modelled to match the new build's performance costs far more carbon. Model the retrofit option that actually meets the brief, and state the assumption.

Operational offsetting. A new building with better operational performance recovers its upfront carbon over time, and the payback period is sensitive to assumptions about grid decarbonisation. A payback calculated against today's grid intensity flatters the new build. State the grid assumption and the period.

Data quality. Generic material datasets and product-specific environmental product declarations give different answers. Record which was used for the major elements.

The Whole Life Carbon Assessment is where the methodology, boundaries and data sources belong, and the planning statement should cite it rather than restate its numbers loosely. Councils normally expect a suitably qualified author for that assessment and professional review is strongly advised.

Viability and deliverability arguments

This is where appraisals get weakest, because the honest answer is often commercial.

The planning test is deliverability, not profitability. An option that produces a lower return is not thereby undeliverable. An option that cannot be funded, cannot be let, or cannot be built within any realistic cost envelope may be.

If you are going to run the argument, run it properly. Use the approach in the Planning Practice Guidance on viability and the RICS professional statement on financial viability in planning, state the inputs, and expect the figures to be tested. A bare statement that refurbishment is uneconomic, with no appraisal behind it, invites the officer to disregard the whole option.

Three deliverability points carry weight without needing a full appraisal: vacant possession constraints across multiple leases, a structural strengthening scope that cannot be carried out with the building in occupation, and a floorplate that cannot be let at any rent in the local market because of its depth or its height.

Programme matters too. A retrofit requiring phased decant across six years, against a rebuild delivering in three, is a material difference where the identified need is immediate.

Heritage and townscape overlap

Where the building is designated, the heritage balance applies and it is more demanding than the carbon argument. Where it is not designated, two routes still exist.

A non-designated heritage asset attracts a balanced judgement having regard to the scale of any harm and the significance of the asset. The effect on the character and appearance of a conservation area, where the building sits within or adjacent to one, engages section 72 of the Planning (Listed Buildings and Conservation Areas) Act 1990.

Townscape value without any heritage designation is a design consideration rather than a heritage one. Deal with it through the design narrative and, where the scheme is tall or prominent, through a townscape and visual impact assessment.

The overlap that catches people out is a retention option that is good for carbon and bad for heritage, or the reverse. A facade retention scheme can deliver poor carbon outcomes, because the temporary works are heavy, and poor heritage outcomes, because what survives is a screen. Say which you prioritised and why.

Presenting the option appraisal

Put the appraisal in the planning statement as a discrete section with its own heading, and keep it short enough to be read.

1. The brief and the identified need, in one paragraph, because every option is tested against it.
2. The options considered, listed with a sketch or a diagram each.
3. The consistent criteria table.
4. The reason each option was set aside, in two or three sentences, cross-referenced to the structural, carbon or viability evidence.
5. The conclusion, stated as a planning judgement rather than as an arithmetic result.
6. The mitigation offered on the preferred option: retained elements, reclaimed materials, the pre-redevelopment audit, the circular economy commitments.

A pre-redevelopment audit of the existing building, identifying what can be reused and reclaimed, strengthens the case even where demolition is accepted. So does a Sustainability Statement that commits to specific reuse targets rather than to aspirations.

Where the proposal is a retrofit rather than a rebuild, the same discipline applies in reverse, and the plant strategy becomes the live question. The permitting side of that is covered in ground source heat pumps and borehole permitting, and the option appraisal logic for large-footprint buildings in energy statements for warehouse and logistics schemes.

Enter your postcode on PlanScope to see which energy and carbon reports a site is likely to need.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. For specialist technical reports, qualified professional input may be required.