Air Quality Neutral Assessments for London Planning

What an Air Quality Neutral assessment is

An Air Quality Neutral (AQN) assessment shows planners that a new development won't make London's air worse. It compares the scheme's predicted emissions with the GLA's benchmarks, set out in the Air Quality Neutral London Plan Guidance (February 2023). If the scheme meets or beats the benchmarks, it is Air Quality Neutral.

It is required by London Plan Policy SI 1, and the GLA's guidance applies it to all development unless it is excluded. There are two checks:

• Building emissions: NOx from boilers, CHP and generators, per m² of floor area.
• Transport emissions: car and van trips made by the people who live in, work at or visit the building.

Who needs one

All development needs an AQN assessment unless it adds no new emission sources. If your scheme has no new car parking, no increase in vehicle trips and no new combustion plant such as gas boilers, it is taken as Air Quality Neutral. You just tell the planning officer that, for example in the cover letter.

Minor schemes get a simplified route. That means 1 to 9 homes, or non-residential schemes under 1,000 m² (or sites under 1 hectare). A minor scheme is taken to meet the building benchmark if it uses heat pumps or another zero-emission heat source, individual gas boilers rated under 40 mg/kWh NOx, or a connection to an existing heat network. It is taken to meet the transport benchmark if the car parking stays within the London Plan maximum standards. Some boroughs still ask for the full method, for example in Air Quality Focus Areas.

Major schemes need the full calculation, and phased schemes have to be Air Quality Neutral as a whole and at the end of each phase.

The building emissions benchmark

The building benchmark is a NOx allowance in grams per m² of gross internal area per year. Each land use has its own rate, and the rate depends on the heating set-up. We add up the allowance for every use in the scheme, then compare it with the predicted emissions: energy use multiplied by the emission rate of each boiler, CHP engine or generator.

What this means in practice:

• Heat pumps count as zero NOx. So does direct electric heating. An all-electric scheme normally passes the building benchmark.
• Gas boilers use up most of the allowance. Low-NOx models with manufacturer data help.
• Wood burners and other solid or liquid fuel appliances can't be Air Quality Neutral. The PM benchmark is zero, so they need mitigation or an offset.
• Emergency generators can be left out if they only run for emergencies and testing, under 50 hours a year, usually secured by condition. Generators used for anything else must be counted.
• A heat network connection isn't an automatic pass. New plant added for the scheme still counts.

The energy figures come from the same SAP and SBEM models as your energy statement, so the planning numbers match.

The transport emissions benchmark

The transport benchmark is a number of car and van trips a year: per home for residential, per m² for other uses. It is lowest in the Central Activities Zone, higher in Inner London and highest in Outer London, where people rely more on cars. Deliveries, servicing, taxis and HGVs aren't part of it; they belong in the wider air quality assessment.

We take the predicted trip rate from your transport assessment, convert peak-hour figures to annual trips where needed, and compare it with the benchmark. A car-free scheme is taken to meet the transport benchmark, but the building emissions still have to be checked.

If the scheme doesn't pass

The GLA sets an order:

1. Change the design first: the heating system, the plant, the parking numbers or the trip-reduction measures.
2. Mitigation: agree extra measures with the borough, on site where possible, in place before occupation and secured by condition or legal agreement.
3. Offset payment: only if mitigation isn't possible. It is worked out from the excess emissions over 30 years and is usually paid through the section 106 agreement.

A good result on one benchmark can't make up for a fail on the other. We look for the affordable, feasible fix at design stage, usually in the heating strategy, before it turns into a section 106 payment.

Planning normally conditions the boiler or plant details and the car parking numbers, so the built scheme must be as good as the one assessed. Later changes to the energy strategy or parking may need the assessment rerun.

What's in our assessment

• The building emissions benchmark and predicted emissions, in tables, for each land use.
• The transport emissions benchmark and predicted trips, in tables.
• Emission factors, trip rates and manufacturer data for any low-NOx plant.
• A clear statement on whether the scheme is Air Quality Neutral.
• If it isn't, the design changes or mitigation that get it there.
• For phased schemes, the whole site and each phase.

We cover the AQN benchmark assessment. Dispersion modelling for a full air quality assessment is a separate job for an air quality consultant.

What's changing: the draft London Plan

Checked 14 November 2026.

The draft new London Plan (published 16 July 2026, consultation closed 15 October 2026) keeps the rule. Draft Policy GHR10 says developments that could affect operational air quality should be at least Air Quality Neutral, with design and on-site solutions first and offsetting only where on-site measures aren't enough. Air Quality Positive applies to schemes that need an Environmental Impact Assessment. Until the new plan is adopted, the London Plan 2021 and the February 2023 guidance apply.

What we need from you

• Floor plans, with the gross internal area for each use.
• The heating and hot water strategy, and the plant make and model if known.
• Any generators, CHP or wood burners, with expected running hours.
• The car parking numbers and the trip rates from the transport assessment (or the transport consultant's contact).
• The borough's pre-app comments or validation checklist, if you have them.

Price and turnaround

No fixed price: it depends on the size of the scheme and the number of uses. Send the details for a free quote. Turnaround is 5 working days once we have everything we need.

Need the energy statement too? We price them together, and the figures carry straight across. Urban Greening Factor needed as well? Same team.

Our experience

More than 17 years in energy assessment, with a mechanical engineering background, and more than 50 energy statements for planning. The building side of an AQN assessment comes from the same heating and plant decisions we model for the SAP, SBEM and energy statement, so one team keeps every planning figure in line.

Questions we get asked

Do minor schemes need an Air Quality Neutral assessment?
Usually only the simplified version. If the homes use heat pumps or boilers under 40 mg/kWh NOx, and the parking stays within the London Plan maximum, the scheme is normally taken as Air Quality Neutral. Some boroughs ask for more, so check the validation checklist or send it to us.

We're using heat pumps. Do we still need it?
Heat pumps count as zero NOx, so the building side normally passes. If the scheme adds car parking or a generator, those still need checking.

Is this the same as an air quality assessment?
No. The AQN assessment checks the scheme against the GLA benchmarks. A full air quality assessment looks at pollution levels on and around the site, often with dispersion modelling, and is done by an air quality consultant. Many boroughs ask for both.

What happens if we fail the benchmark?
Design changes first, then mitigation agreed with the borough. An offset payment is the last resort. We'll show you the cheapest way to close the gap.

Related: Energy statements · Community heating feasibility · Urban Greening Factor calculations · Carbon Reduction Plans (PPN 006) · The London Plan energy hierarchy · SBEM calculations · SAP calculations · Solar PV for SAP and SBEM · Energy assessments in London · Commercial services · New dwellings · TM59 dynamic overheating · Case studies · Industry updates

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