ACP Insights & Guidance
An air quality neutral assessment checks a London development against the applicable building and transport benchmarks. Coordinate the energy strategy, development schedule and transport evidence while design choices remain open.
The practical answer
Start with the London Plan and the GLA’s adopted guidance. Confirm whether an assessment, an excluded-development route or the simplified minor-development approach applies. Keep building and transport results separate, and assess exposure and wider air quality effects where needed.
Where does an air quality neutral assessment apply?
This guide concerns the London Plan route. Policy SI 1 addresses air quality, including the requirement for development proposals to be at least air quality neutral. The GLA’s adopted Air Quality Neutral guidance, published in February 2023, explains the benchmark approach and a simplified route for minor development.
Check the proposal’s scope, the current guidance and the relevant borough’s requirements. Do not apply London’s benchmark process automatically to every English planning application. Outside London, identify the applicable local policy and validation requirements.
Our London air quality guidance provides the wider local context. A clear appointment should state whether the project needs an AQN assessment, other air quality work, or both.
Separate neutrality, exposure and wider impacts
An AQN result does not answer every air quality question. The wider assessment may need to consider existing pollution affecting future occupants, effects on neighbours, construction activities or sensitive habitats. Identify those workstreams separately.
Also distinguish Air Quality Neutral from Air Quality Positive. London Plan Policy SI 1 describes a positive approach for the relevant large-scale masterplanning context. The terms should not be used interchangeably in a report or design statement.
For the broader scope, use our air quality assessment service. Ask the assessor to explain which conclusions each part of the evidence package supports, so a benchmark result is not overstated.
Agree the air quality neutral assessment inputs
| Workstream | Information to coordinate | Check before issue |
|---|---|---|
| Development description | Uses, floorspace or other relevant units, phasing and drawing revision. | The same development appears in every supporting report. |
| Building emissions | Energy strategy, plant schedule and inputs required by the current method. | Provisional equipment and assumptions are identifiable. |
| Transport emissions | Transport scenario, land-use information and the applicable benchmark inputs. | Transport and air quality teams use consistent data. |
| Design response | Options, changes and any proposed mitigation route. | Actions have owners and evidence of resolution. |
| Submission | Final calculations, limitations and supporting references. | The assessment matches the submitted scheme. |
The exact calculation inputs depend on the applicable guidance and proposal. Therefore, ask the assessor to issue a project-specific request rather than assuming this coordination table is the calculation method.
Keep a short assumptions register. For each material input, record its source, date, owner and status. This helps the assessor identify which values need confirmation and makes later design changes easier to review.
Understand what the benchmark comparison means
The GLA guidance, sections 3 and 4, addresses building and transport emissions through separate benchmarks. The assessor should explain the calculation basis, relevant development categories and how each result compares with its benchmark. Do not present only a combined headline result.
A clear report distinguishes the proposed design from any assumed future improvement. For example, an unconfirmed equipment substitution should not quietly become the basis of the final calculation. Record which commitments form part of the submitted proposal.
Similarly, keep units and input definitions visible. A difference between gross and net area, development phases or transport scenarios can undermine an otherwise correct calculation. Resolve those mismatches with the relevant designers before the report is issued.
| Record | Check and action |
|---|---|
| Building Emissions Benchmark (BEB) | Show the relevant development inputs, energy assumptions, predicted building emissions, benchmark and separate conclusion. |
| Transport Emissions Benchmark (TEB) | Show the relevant development category, transport inputs, predicted trip rate, benchmark and separate conclusion. |
| Design response | Identify which result needs action. Record the agreed change and update the calculation before reporting the final position. |
This is a reporting prompt, not a calculation tool. Use the adopted method and its units; a favourable result in one workstream does not cancel an exceedance in the other.
Resolve a benchmark exceedance through the design process
Section 5 of the adopted guidance puts design amendments first where benchmarks are not met. It then describes agreement of mitigation and, where appropriate at the authority’s discretion, offsetting. A payment should not be treated as an automatic substitute for design review.
Use the assessment to identify the driver of the result. Ask which inputs or design choices materially affect it and which alternatives are feasible. The energy, transport and air quality teams should review those options together.
Record the preferred response and its implications for other reports. For example, a plant change may affect noise, energy and servicing. A transport change may affect parking, access or the travel plan. Update the shared evidence rather than fixing one calculation in isolation.
Example: the energy strategy changes after the calculation
Illustrative coordination example
A development team completes an early AQN assessment using a provisional energy strategy. The mechanical design later changes, but the air quality report is still listed as complete on the submission tracker.
The project manager compares the assumptions register with the latest plant schedule and identifies the mismatch. The assessor reviews the revised inputs and updates the relevant conclusion. The team also checks the acoustic and energy reports against the same design.
This example does not predict whether a specific system meets a benchmark. It shows why a completed report needs a defined design basis and a change-control process.
Keep the assessment useful through planning and delivery
Before submission, check the final report against the application description, drawings and supporting strategies. List unresolved assumptions explicitly. If the authority requests further information, maintain a record of which version answers each request.
After approval, retain the commitments that affect the assessed scheme. Material substitutions or changes may need specialist review and consideration against the permission. Do not assume an earlier benchmark result applies to a different design.
- Confirm the current London and borough requirements.
- Separate AQN from exposure and construction assessment.
- Agree consistent building and transport information.
- Resolve design changes before issuing final calculations.
- Record the evidence behind any agreed mitigation.
- Carry relevant commitments into design and handover records.
Common questions
Is air quality neutral the same as an air quality assessment?
No. AQN is a particular benchmark assessment. A wider air quality assessment can address exposure, construction and operational effects that the benchmark exercise does not resolve.
Does every project use the same AQN procedure?
No. The GLA guidance includes different provisions, including a simplified approach for minor development. Confirm the correct route for the actual proposal and borough requirements.
Can better building emissions cancel transport emissions?
Do not assume that they can. The guidance treats the building and transport benchmarks separately. Ask the assessor to explain each result and any necessary response.
Can we pay an offset instead of changing the design?
Do not treat offsetting as automatic. The guidance prioritises design changes and sets out subsequent mitigation and discretionary offsetting arrangements with the authority.
Does passing AQN mean the site’s air is safe for every proposed use?
No. Existing pollution and exposure of future occupants may require separate assessment. Keep the benchmark conclusion within its stated scope.
References and scope
London planning briefing checked against the official adopted guidance. It does not calculate emissions, determine policy compliance or substitute for borough-specific advice.
- Greater London Authority. Air Quality Neutral London Plan Guidance, adopted 8 February 2023.Current official guidance hub; London-specific scope.
- Greater London Authority. Air Quality Neutral London Plan Guidance, February 2023.Assessment and mitigation framework. Use the applicable document and calculation requirements for the actual scheme.
- Greater London Authority. London Plan 2021, Policy SI 1: Improving air quality.Policy context, including the distinction between neutral and positive approaches.
- GOV.UK. Planning practice guidance: Air quality.England-wide context for development impacts and exposure; not a national AQN benchmark requirement.