Getting a product footprint ready for assurance

What assurance means for a product footprint

Assurance is an independent review of your footprint that ends in a written conclusion about it. Verification is one form of it. For greenhouse gas statements, ISO 14064-3:2019 sets out how verification is carried out, and ISO 14065:2020 sets the requirements for the bodies that do it.

Choose a verifier accredited for the relevant scope. In the UK, accreditation is given by UKAS, the United Kingdom Accreditation Service. Agree three things with the verifier in advance: the standard it will check against, the materiality threshold it will apply, and the level of assurance.

Assurance has to come from a body independent of whoever prepared the footprint. ESGen prepares footprints and evidence; it does not assure, verify or certify them.

Agree the request before you calculate

Much rework comes from calculating the wrong thing. Before you start, confirm with your customer the product, the unit, the boundary, the standard, the reference period and whether assurance is needed at all.

Check whether a product category rule or sector guideline applies. Where one exists, verifiers will usually expect it to be followed. Then plan for the verifier from day one: keep every data source, calculation and assumption in a form someone outside your business can follow.

If you have not calculated the footprint yet, start with our step-by-step calculation guide.

What verifiers look for

A verifier checks that each figure follows the standard you named and can be traced to its source. Common findings in a first assurance include:

• A reference period that is not typical, or data mixed from different years.
• An emission factor that does not match the activity or the country.
• An allocation method applied to some products but not others.
• Supplier figures used without any evidence of how they were worked out.
• Exclusions listed without an estimate of their size.

Exclusions deserve extra care. Set your cut-off criteria before you calculate, based on mass, energy or likely emissions, and apply them the same way throughout. ISO 14067 requires the criteria and their effect to be stated. PAS 2050:2011 from BSI goes further and requires the footprint to cover at least 95% of the product's expected life cycle emissions within the boundary. Other standards set their own tests, so check yours.

Factors get close attention too. For every one, record the source, version, year and geography. If a supplier gives you its own product factor, ask how it was calculated and whether it was assured before you rely on it.

Electricity is another common question. If you use renewable electricity certificates, they should meet the quality criteria in the GHG Protocol Scope 2 Guidance and cover the right site and period. Some customers ask to see the result both with and without those certificates, so keep both.

The evidence file to have ready

Put this together before the verifier's first visit:

• The footprint report: product, unit, boundary, standard, method, data, results and exclusions.
• The calculation model, with every formula visible.
• Source documents for activity data: meter reads, invoices and production records.
• Emission factor sources and versions.
• Supplier data and the evidence behind it.
• Allocation methods, cut-off decisions and exclusions, each with its reason.
• A named person who can answer questions.

Keep it current and word claims with care

A footprint describes one product in one period. Review it when the bill of materials, a main supplier, the process, the site, the energy supply or the required method changes. Keep earlier versions and the reason for each change, because customers comparing years will ask why the number moved.

When you share the figure, say what it is. A clear statement follows this pattern, with your own details in the marked fields:

Take care before using the figure in marketing. The Competition and Markets Authority's Green Claims Code sets out how environmental claims must be accurate and backed by evidence. Under the Digital Markets, Competition and Consumers Act 2024, the CMA has been able to fine firms directly for misleading consumer claims since April 2025.

A footprint on its own does not support a claim that a product is carbon neutral. ISO 14068-1:2023 sets the requirements for that, including reductions and the quality of any credits. Do not compare your footprint with a competitor's unless both were calculated under the same rules.

How ESGen helps

Product footprints are a service our team scopes with you. We calculate the footprint to the standard your customer names and assemble the evidence file above, so the verifier's questions have answers on paper. The ESGen platform keeps the bill, emission factor and calculation record behind each site energy figure, which is the site-level evidence a verifier will ask to see.

We do not assure, verify or certify footprints; an independent verifier does. Read more on product footprints, or book a demo to talk through your customer's request.