How to Report Your Emissions to an Airport: A Guide for Suppliers

Quick Answer: To report your emissions to an airport, measure your organisational carbon footprint using the GHG Protocol, covering Scope 1 and 2 and, where requested, Scope 3. Then present it in the format the airport asks for, such as a questionnaire, scorecard, EcoVadis assessment or Carbon Reduction Plan, with your reduction targets and plans. Airports ask because supplier emissions form part of their own footprint: at Heathrow, Scope 3 accounted for 99% of reported emissions in 2025.

Why are airports measuring their emissions?

Most airports have made commitments to reduce their emissions, which means they need to measure their carbon footprint to establish a baseline and track progress. 

Through ACI EUROPE, more than 300 European airports had disclosed roadmaps towards net zero carbon emissions under their control by 2050, with 118 setting earlier targets of 2030 or sooner. In England, the UK Government's 2022 Jet Zero Strategy set an ambition for all airport operations to be zero emission by 2040.

Many airports report their progress through Airport Carbon Accreditation (ACA), a global carbon management certification programme launched by ACI EUROPE in 2009. It is a voluntary programme: airports choose to apply, then work through seven levels. Accreditation provides a framework for reducing emissions, but the reductions depend on what each airport does. In the latest annual results, covering May 2024 to May 2025, 590 airports across 91 countries and territories were accredited, together handling 53.6% of global passenger traffic (Airport Carbon Accreditation, March 2026). They included Heathrow, Gatwick, Edinburgh, Birmingham, Paris Charles de Gaulle, Madrid, Munich and Dublin, all at Level 3 or above (ACA Annual Report 2024 to 2025). 

Why do airports ask suppliers to report their emissions?

ACA's higher levels place greater emphasis on emissions beyond an airport's direct control, including those from suppliers and other third parties. Without supplier data, airports may estimate these emissions from how much they spend with each business. A spend-based estimate reflects the value of a purchase, not the supplier's actual footprint, which makes it harder to reflect when a supplier reduces its emissions. Heathrow, for example, now uses supplier-specific emissions factors in place of spend-based ones where suppliers have provided evidence of third-party assurance.

For suppliers, a request for carbon data is usually part of an airport's effort to measure its footprint more accurately and track progress against its targets.

What are organisational emissions?

ACA’s requirements are built around organisational emissions and the three scopes, so it helps to understand them before looking at what an airport asks of its suppliers. Organisational emissions are the greenhouse gases your business emits as a result of its activities over a reporting period, measured in tonnes of carbon dioxide equivalent (tCO₂e). They cover the whole business, rather than a single product or project. The GHG Protocol Corporate Standard sets out how to calculate them, and ACA's requirements are aligned with the GHG Protocol and the principles of ISO 14064, so airports and their suppliers are working from the same framework.

What are Scope 1, 2 and 3 emissions?

The GHG Protocol divides organisational emissions into three scopes:

An airport's Scope 3 emissions include the goods and services it buys, so when you supply an airport, your emissions can form part of its Scope 3 footprint. Our guide to Scope 3 emissions explains how this works.

What does Airport Carbon Accreditation require?

ACA has seven levels, with progressively more demanding requirements for measuring and reducing emissions. Here's what each level involves and why it matters to suppliers.

What do UK airports ask suppliers for?

If you supply an airport, you may be asked to share sustainability information as part of a tender, a supplier assessment or an ongoing contract. The exact requirements depend on the airport and the work you do for it. The table summarises what six UK airports publish. 

Manchester Airports Group requires suppliers to complete an EcoVadis sustainability assessment within six months of contracting. Our guide to improving your EcoVadis score explains what assessors look for. 

How do you report your emissions to an airport?

The exact requirements vary, but the process is broadly the same: calculate your carbon footprint, keep evidence to support your figures, and present the results in the format your airport client requests.

1. Check what the airport needs

The information required depends on the goods or services you provide and your relationship with the airport. Some requests are specific to your activities. ACA guidance, for example, identifies fuel use and mileage for contracted vehicles, and fuel type and operating hours for ground support equipment (ACA Level 4 and 4+ Requirements, 2026).

Before you start, check the tender documents, supplier code or questionnaire. If anything is unclear, ask your contact at the airport. Heathrow, for example, advises bidders to use the policy documents provided in the tender and raise questions through the tender process (Heathrow Supplier Support and Tools).

2. Set your reporting boundary and period

Decide which parts of your business to include, following the GHG Protocol's guidance on organisational boundaries. Use the reporting period specified by the airport. If none is given, a consistent 12-month period is a sensible starting point.

3. Collect your activity data

Gather records of what your business uses and does, including fuel, electricity, refrigerant top-ups, business travel, staff commuting, waste and purchased goods and services.

Where possible, use actual activity data, such as litres of fuel consumed or electricity used in kWh. If you don't have detailed data for some activities, spend-based estimates can help fill gaps, particularly for Scope 3 emissions from purchased goods and services.

4. Calculate your emissions

Convert your activity data into tonnes of carbon dioxide equivalent (tCO₂e) using recognised emission factors. For UK operations, the UK Government greenhouse gas conversion factors provide factors for a range of activities. Use the factors appropriate to your reporting year.

5. Present your figures and reduction plans

Follow the airport's requested format. Depending on its requirements, you may need to provide:

• Emissions totals by scope, in tCO₂e
• An emissions intensity figure, such as tCO₂e per £m of revenue
• Your reduction targets and the actions you're taking to meet them

If no specific format is required, a straightforward report covering your footprint, main emissions sources and reduction plans is a useful starting point. Our free climate transition plan example shows how to set out targets and actions.

6. Keep your evidence and update your figures

Keep the records behind your calculations, including energy bills, fuel receipts, travel records and emission factors. Good documentation makes your figures easier to check and update each year.

If you're completing an EcoVadis assessment, supporting evidence and a clear accounting methodology help demonstrate the reliability of your carbon data. EcoVadis distinguishes between data rated High and data that is Third-Party Verified, with both identified as suitable for external reporting.

Some airports may also require independent verification. Where requested, verification against the relevant requirements of ISO 14064 can provide additional assurance over your emissions figures.

What are your options for producing emissions data?

Once you know what your airport client needs, there are three main ways to produce the data.

Do it yourself

You can calculate your carbon footprint using spreadsheets, the GHG Protocol and UK Government greenhouse gas conversion factors. This can be a cost-effective option for straightforward reporting, particularly if you're focusing on Scope 1 and 2 emissions.

The challenge is knowing which methods to use, collecting the data you need for Scope 3, and repeating the process each year as your business and reporting requirements change.

Hire a carbon consultant

A carbon consultant can calculate your footprint, help you understand your main emissions sources and prepare the reports you need. This can be a good option for a one-off project or a more complex footprint.

However, you'll need to consider how your data will be maintained and updated in future years, including whether further consultancy work will be needed.

Use carbon accounting software with expert support

Carbon accounting software helps you bring your emissions data and calculations together in one place, making it easier to update your footprint each year and use the results for different reporting requirements. Expert support can also help you apply the right methodology, improve data quality and understand what your results mean.

This is what Seedling combines: carbon accounting software with one-to-one support from a carbon expert. We help you build an accurate footprint and use it to respond to airport clients' reporting requirements.

Case study: how Mima measures and reports emissions to airport clients with Seedling

Mima is a London-based design consultancy and certified B Corp that advises airports on wayfinding, ergonomics and accessibility. Its airport clients include Heathrow, Gatwick, Stansted, Luton, Dublin and Schiphol.

As a professional services supplier, Mima's activities contribute to its airport clients' Scope 3 emissions. Earlier attempts to measure its emissions manually had proved difficult and time-consuming. With Seedling's software and one-to-one support, Mima built a full-scope carbon footprint in a little over a month. As the team put it: "Seedling removed the 'this will take years' barrier to measuring emissions."

The footprint showed that business-class flights were among Mima's largest sources of emissions. However, its policy on these flights supports colleagues with accessibility requirements, so rather than changing the policy outright, Mima plans to assess trips individually and explore alternatives where people's needs and schedules allow. This could reduce emissions by an estimated 6.6 tCO₂e a year.

Mima is now developing a 10-point reduction plan with Seedling. It can respond to clients' questions about its footprint and reduction plans with greater confidence, and give airport clients more specific data than a spend-based estimate.

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