--- title: "Product carbon footprint verification:\nhow to get the calculation a customer asks for verified" description: "Product carbon footprint verification: expert review, ISO 14071 critical review, ISO 14064-3 verification or PACT. Who can verify a customer's calculation, and how." canonical: https://projetcelsius.com/en/blog/product-carbon-footprint-verification/ author: "Guillaume Pakula" datePublished: 2026-10-17 dateModified: 2026-10-17 language: en translationOf: https://projetcelsius.com/blog/empreinte-carbone-produit-verification/ --- # Product carbon footprint verification: how to get the calculation a customer asks for verified **Author**: Guillaume Pakula **Published**: 2026-10-17 **Section**: Practical guide **Canonical URL**: https://projetcelsius.com/en/blog/product-carbon-footprint-verification/ **French original**: https://projetcelsius.com/blog/empreinte-carbone-produit-verification/ **Source**: Projet Celsius (https://projetcelsius.com/en/), a climate strategy consultancy of engineers and PhDs based in Paris and Marseille. > A product carbon footprint is verified by a **third party independent of the calculation**, against the standard the customer cites: **ISO 14064-3**, a critical review under ISO 14071 or the **PACT methodology**. No general rule requires it for a figure passed to a customer; the requirement comes from the contract, the standard or the programme in which the figure is published. **No public price list** sets the price: it depends on the number of products, the level of assurance and the state of the file. ## Key takeaways - **The verifier must be independent** of the calculation and of the tool that produced it. - **PACT requires a third party** and limited assurance until 2030. - **A verified calculation model** covers a whole product range for up to 3 years. - **Ask the customer what the figure will be used for** before ordering the verification. The [PACT methodology](https://www.wbcsd.org/resources/pact-methodology-version-3/), from the Partnership for Carbon Transparency, is the framework for exchanging product carbon footprints between companies, published by the World Business Council for Sustainable Development (WBCSD). Since its version 3 of 30 April 2025, it requires the **calculation model** to be verified by an independent third party. A supplier that passes the [carbon footprint of a product](https://projetcelsius.com/en/blog/product-carbon-footprint-lca-pef-cfp/) to its customer should therefore expect the next question: has this figure been verified, and by whom? The answer depends on **what the customer will do with the figure** and **who calculated it**. The sections below start from those 2 questions. ## Which verification does the customer expect? Behind a "verified" footprint, a customer may expect **4 approaches** that do not offer the same guarantee. They share one rule: **whoever checks the calculation did not take part in it**. Before ordering anything, you need to know which one the customer expects: - An **expert review**: a life cycle assessment specialist reads the report and the calculation file, then returns comments. It makes the figure more reliable without a formal statement. - A **critical review**, governed by the [ISO 14071:2024](https://www.iso.org/standard/86264.html) standard: it checks that a study based on life cycle assessment complies with the standards, and produces a **review report** attached to the study. Our guide to [choosing a critical review expert (in French)](https://projetcelsius.com/blog/revue-critique-acv-choisir-expert-independant/) *(in French)* sets out how it runs. - **Verification under ISO 14064-3**, which also applies to a product's greenhouse gas statements ([ISO](https://www.iso.org/fr/standard/66455.html)): the verifier concludes with **limited or reasonable assurance**. - **Verification of a calculation model**, required by PACT from 2025 to 2030: the third party checks **the tool that produces the footprints**, rather than each footprint one by one. ### What ISO 14067 says [ISO 14067:2018](https://www.iso.org/fr/standard/71206.html) sets the requirements for quantifying the carbon footprint of a product, consistently with the life cycle assessment standards. **Confirmed in 2024**, it is under revision. It **excludes communication** of the footprint from its scope: publishing a figure falls under another standard, [ISO 14026](https://www.iso.org/fr/standard/67401.html), which also sets requirements for the verification procedures of communication programmes. ### Limited or reasonable assurance Under **limited assurance**, the verifier concludes in the negative: nothing has come to its attention suggesting that the calculation does not comply. Under **reasonable assurance**, it concludes positively, which requires **more evidence and testing**. PACT requires limited assurance until 2030. ## Is it mandatory, and who requires it? No general rule requires a carbon footprint passed to a customer to be verified. The requirement comes from the **contract**, from the **standard** the customer cites or from the **programme** in which the figure will be published. The 3 cases are read differently. ### The customer's contract and standard The 2011 [GHG Protocol Product Standard](https://ghgprotocol.org/sites/default/files/standards/Product-Life-Cycle-Accounting-Reporting-Standard_041613.pdf) requires a product inventory to be **assured by a first or third party**. A person within the company may do it, provided they **stayed outside the calculation** and state how the conflict of interest was avoided. PACT goes further and requires an independent third party. A customer that cites either one in its specification therefore sets, without spelling it out, **the level of verification expected**. ### PACT and sector frameworks PACT methodology V3 organises verification over 2 horizons. The timetable comes down to 4 rules: - From 2025 to 2030, the company has its **calculation model** verified by an independent third party, with limited assurance, across the whole cradle-to-factory-gate scope. - From 2030, the company's **footprint programme**, with its governance, data and calculations, must be certified by a third party. - A verification statement is valid for **3 years at most**, or until a change of method or tool, and a new verification is required if the footprint varies by more than 10%. - **SMEs** follow the same requirements with a 2-year lag, that is from 2027 for verification of the calculation model. - Any company may exchange a footprint before it is verified, while it prepares, even though PACT writes verification as an obligation. PACT refers to **sector rules** where they exist: Together for Sustainability for chemicals, Catena-X for the automotive industry, the Global Battery Alliance for batteries. The graphic below shows what each one asks for, and our guide to the [LCA of an industrial battery](https://projetcelsius.com/en/blog/industrial-battery-lca-how-to-start/) covers the case of batteries in detail. ### Public and regulated declarations A footprint **intended for publication** falls under a different regime. An [FDES or Product Environmental Profile (PEP)](https://projetcelsius.com/en/blog/fdes-pep-choose-accredited-verifier/), the French formats of environmental product declaration (EPD) for construction products and for electrical and HVAC equipment respectively, goes through the approved verifier of its programme. An [environmental claim](https://projetcelsius.com/en/blog/banned-environmental-claims-eu/) about a product must be provable, and the [EmpCo](https://projetcelsius.com/en/blog/what-is-empco-directive/) directive (on empowering consumers for the green transition) prohibits, in the countries that have transposed it, presenting a product as [carbon neutral](https://projetcelsius.com/en/blog/carbon-neutral-claims-what-companies-can-say/) on the strength of offsetting. For steel, aluminium, cement, fertilisers, hydrogen and electricity imported into the European Union, the [carbon border adjustment mechanism (CBAM)](https://projetcelsius.com/en/blog/cbam-free-allowances-phase-out/) has the actual emissions declared by the importer verified by an **accredited verifier**. Without verified data, it applies the Commission's default values. For electric vehicle batteries and industrial batteries of more than 2 kWh, [EU Regulation 2023/1542](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32023R1542) provides for a **carbon footprint declaration** checked by a notified body. It will apply only once the Commission has adopted its calculation method, which is still awaited. ## How do you choose the verifier? The criterion that is not negotiable is **independence**: the GHG Protocol requires the assurer to have been involved in neither the calculation nor the statement. The firm or software vendor that built the model **therefore cannot verify it**, even if it knows it better than anyone. Competence comes next, then accreditation, where the customer asks for it. ### Competence PACT expects the verifier to have **proven experience** in carbon accounting, in [life cycle assessment](https://projetcelsius.com/en/blog/lca-vs-carbon-footprint/) or in product footprinting, and knowledge of the ISO 14067, ISO 14064-3 and ISO 14044 standards. A verifier that knows the customer's processes spots an implausible data point faster: **sector knowledge** counts as much as knowledge of the standards. ### Accreditation Some customers require a body accredited under [ISO 14065](https://www.iso.org/fr/standard/74257.html), the standard for bodies that validate and verify environmental information statements. Others accept **a qualified independent expert**. Our guide to [verifying an in-house carbon footprint assessment (in French)](https://projetcelsius.com/blog/bilan-carbone-interne-verification-tiers/) *(in French)* sets out what accreditation covers. Before signing, these questions help decide between 2 proposals: - Did the verifier take part, closely or remotely, in the calculation, in the choice of the tool or in the training of the team that produced the footprint? - Which standards will the statement cite, and is the standard required by the customer among them, with its version? - How many products or test cases will be recalculated, and on which real data rather than on examples supplied for the occasion? - What happens if a discrepancy is found: correction time limit, new visit, and effect on the price and on the date of the statement? ## How does the verification work? A verification starts with a **scoping step**: the object verified (a product, a range, a calculation model), the standards, the level of assurance and the scope. The verifier then reads the method, recalculates test cases, traces a sample back to the activity data and notes discrepancies. The company **corrects or justifies**, then receives the statement. What to read in that statement comes down to 7 sections: The section that matters most is the first, **the object verified**. A statement covering a **calculation model** covers all the footprints it produces during its validity. PACT retains this route until 2030 to verify at scale. ### Lead time and price **No public price list** sets the price of a product footprint verification. It depends on the **number of products** or the complexity of the model, the level of assurance, the number of sites to trace back and **the state of the file**. The lead time depends mainly on the quality of the file. For the study itself, our guide to the [price of an LCA](https://projetcelsius.com/en/blog/lca-cost/) gives benchmarks. ## What should you prepare before having your footprint verified? A **complete file** before the first meeting shortens the engagement and avoids back-and-forth. These documents form the core: - The **study report** under ISO 14067: declared unit, scope, allocation rules, **justified exclusions** (3% at most under PACT), assumptions and limitations. - The **calculation file or tool**, with the version used and the history of changes since the last calculation passed to the customer. - The **activity data** for the chosen year: energy consumption by site, bills of materials, quantities of materials and transport, with supporting evidence. - The **list of emission factors** and their sources, with the database version and **the Intergovernmental Panel on Climate Change (IPCC) report** the global warming potentials come from, the latest one according to PACT. - The **share of primary data** in the footprint, which PACT already requires companies to declare, and the data quality rating, which it requires by the end of 2027. ### Recurring discrepancies Verifications often stumble on the same points: global warming potentials taken from **an older IPCC report**, or an **allocation between co-products** that changes from one product to another. Electricity counted with a factor that does not match the purchase contracts also recurs, as does **biogenic carbon** counted without being flagged. The calculation method set out in the guide to the [product carbon footprint](https://projetcelsius.com/en/blog/product-carbon-footprint-lca-pef-cfp/) helps settle these choices before verification, and a [first eco-design LCA](https://projetcelsius.com/en/blog/first-product-lca-steps-cost-mistakes/) often lays the foundations of the model. > For each figure in the footprint, a verifier looks for the evidence that allows it to be traced back. ### Reusing the verification A footprint that has already been verified **does not have to be verified again** as long as the model and the data do not change, PACT specifies, and the customer who receives it saves time on its own verification. A supplier preparing its [reply to a carbon data request](https://projetcelsius.com/en/blog/customer-carbon-data-request/) **attaches the statement**, and a buyer who [checks its suppliers' data](https://projetcelsius.com/en/blog/verify-supplier-emissions-data/) reads **the object verified and the validity date** in it. The same file will serve tomorrow for the [digital product passport](https://projetcelsius.com/en/blog/digital-product-passport-explained/). For us at Projet Celsius, the first question to ask the customer is about **what the figure will be used for**: a Scope 3 calculation, a PACT platform or a public communication do not call for the same verification. We then recommend **having the calculation model verified** rather than a single product, as soon as several product references are requested: the verification then serves the whole range for up to 3 years. ## Key takeaways - **No general rule** requires a carbon footprint passed to a customer to be verified: the requirement comes from the contract, the standard or the publication programme. - The GHG Protocol Product Standard allows internal assurance independent of the calculation; **PACT requires an independent third party** and limited assurance until 2030. - From 2025 to 2030, PACT accepts **verification of the calculation model**, valid for 3 years at most, rather than verification of each product footprint. - The firm or software vendor that built the calculation **cannot verify it**; outside a regulated programme, ISO 14065 accreditation is needed only if the customer asks for it. - A **complete file**, with an ISO 14067 report, a versioned tool and sourced data and factors, saves more time than anything else. For the calculation method itself, the guide [product carbon footprint: which method?](https://projetcelsius.com/en/blog/product-carbon-footprint-lca-pef-cfp/) sets out the ISO 14067 rules. ## Frequently asked questions ## Frequently asked questions ### Can a product carbon footprint be certified? It is verified rather than certified: an independent third party checks the calculation under ISO 14064-3, or carries out a critical review under ISO 14071, then issues a statement or a report. Certification in the PACT sense applies, from 2030, to the company's footprint programme, not to an individual product. ### What is the ISO 14067 standard? It is the international standard for quantifying the carbon footprint of a product, published in 2018, confirmed in 2024 and under revision. It builds on the life cycle assessment standards ISO 14040 and ISO 14044 and covers climate change only. Communication of the footprint falls outside its scope and comes under ISO 14026. ### Does the PACT methodology require verification? Yes. Since version 3 of April 2025, PACT requires, from 2025 to 2030, verification of the calculation model by an independent third party, with limited assurance, then certification of the footprint programme from 2030. SMEs have a 2-year lag, and any company may exchange a footprint before it is verified. ### What is the difference between a critical review and a verification? A critical review, governed by ISO 14071, checks that a study based on life cycle assessment complies with the standards, often while the study is under way. Verification under ISO 14064-3 ends in an assurance conclusion, limited or reasonable, on a quantified statement. A customer may ask for one or the other, or for the 2 together. ### How long does a verification remain valid? Under PACT, a verification statement is valid for 3 years at most, or until the calculation method or tool changes. A new verification is also required when the footprint varies by more than 10%. Outside PACT, the duration depends on what the contract with the customer and the statement itself provide. ### Can the firm that did the calculation also verify it? No. The GHG Protocol Product Standard requires the assurer to have taken part in neither the calculation nor the statement, and PACT requires an independent third party. The firm or software vendor that built the model can help prepare the file, but the verification falls to someone else. ## Sources **Sources**: [WBCSD, PACT Methodology Version 3, published 30 April 2025, section 5 "Verification", accessed 16 October 2026](https://www.wbcsd.org/resources/pact-methodology-version-3/); [GHG Protocol, Product Life Cycle Accounting and Reporting Standard, 2011, chapter 12 "Assurance"](https://ghgprotocol.org/sites/default/files/standards/Product-Life-Cycle-Accounting-Reporting-Standard_041613.pdf); [ISO 14067:2018, carbon footprint of products, confirmed in 2024](https://www.iso.org/fr/standard/71206.html); [ISO 14064-3:2019, verification and validation of greenhouse gas statements](https://www.iso.org/fr/standard/66455.html); [ISO 14071:2024, critical review in life cycle assessment](https://www.iso.org/standard/86264.html); [ISO 14026:2017, communication of footprint information, confirmed in 2026](https://www.iso.org/fr/standard/67401.html); [ISO 14065:2020, validation and verification bodies](https://www.iso.org/fr/standard/74257.html); [Regulation (EU) 2023/1542 concerning batteries, Articles 7 and 17, EUR-Lex](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32023R1542); [Regulation (EU) 2023/956 establishing a carbon border adjustment mechanism, Article 8, EUR-Lex](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32023R0956); [Directive (EU) 2024/825 (EmpCo), Annex I, EUR-Lex](https://eur-lex.europa.eu/eli/dir/2024/825/oj).