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How to Verify a Sustainability Claim

Practical steps for checking what suppliers tell you

6 min readUpdated April 2026Sign in to save

Why you should verify claims yourself

Sustainability claims are everywhere in construction product marketing. 'Low carbon', 'recycled', 'sustainable', 'natural', 'eco-friendly' - these terms are used freely and often without standardised definitions. Some are backed by rigorous third-party evidence. Others are marketing language with no verifiable substance.

Matera applies its own verification process to certifications, carbon data, and sourcing claims. But even with platform-level checks, procurement professionals should understand how to verify claims independently. It protects you from greenwash, strengthens your audit trail, and gives you confidence when defending material choices to clients and assessors.

Step 1: Check the certification

Certifications are the most concrete form of sustainability claim. They involve a defined standard, an independent assessment, and a public registry. Checking them is straightforward.

1.Identify the certification body

Is it a recognised scheme (FSC, PEFC, C2C, BRE)? Self-declared eco-labels carry less weight.

2.Find the certificate number

Every legitimate certification has a verifiable licence code. No code = no certification.

3.Verify on the issuer's database

Check the certificate is current, covers the right product, and hasn't been suspended or withdrawn.

4.Check the expiry date

Certifications expire. A claim based on a lapsed certificate is not valid.

Tip. On Matera, certifications with a green 'Verified' badge have already been checked against external registries. But if you need to reference the certificate in a tender submission or BREEAM evidence, verify it yourself as well - assessors expect primary evidence.

Step 2: Check the carbon data

If a product claims low embodied carbon, the evidence should be an Environmental Product Declaration (EPD) or equivalent lifecycle assessment.

TopicDetail
Request the EPD documenta genuine EPD is publicly available and registered with a programme operator. If the supplier cannot provide a link or document, the claim is unverified.
Check the declared unitthe carbon figure only makes sense in relation to its declared unit (per m², per kg, per m³). A figure quoted without a unit is meaningless.
Check the lifecycle scopeA1–A3 covers production only. A1–A5 includes construction. A1–C4 is whole life. Make sure you are comparing like with like.
Check the product matchan EPD covers a specific product or product range. If the supplier is using an EPD for a different product in their range, or a generic industry EPD, the figure may not apply to the product you are specifying.
Check the dateEPDs typically have a five-year validity. An expired EPD may still be directionally useful but should not be relied on for formal reporting.

Step 3: Check recycled content claims

Recycled content is one of the most commonly claimed sustainability attributes, and one of the easiest to misrepresent.

TopicDetail
Ask whether the figure is pre-consumer or post-consumerpre-consumer (also called post-industrial) recycled content includes factory offcuts and process waste, which is standard practice in many industries. Post-consumer recycled content is genuinely recovered material from end-of-life products. The distinction matters.
Ask for the basis of the claimis the percentage by weight, by volume, or by component? A product with a recycled steel frame and a virgin insulation core might claim 'recycled content' without specifying that only 30% of the product by weight is recycled.
Check whether the claim is certifiedsome certification schemes (e.g. Cradle to Cradle, BES 6001) include audited recycled content verification. A certified figure carries more weight than a self-declaration.
Ask about consistencyrecycled content can vary between batches depending on feedstock availability. A supplier claiming 60% recycled content should be able to tell you whether that is a guaranteed minimum or an average.

Step 4: Check sourcing and origin claims

Claims about local sourcing, origin, and supply chain transparency are harder to verify than certifications but still worth checking.

TopicDetail
Ask where the raw materials come fromnot where the product is packaged or distributed from. 'Made in UK' may mean assembled in the UK from imported components.
Ask about the supply chainhow many processing steps are there between raw material and finished product? The more steps, the more transport emissions and the harder it is to verify origin claims.
Cross-reference with Matera's sourcing dataif the product has verified sourcing on the platform, the origin country, manufacturing location, and component breakdown have been reviewed. Use this as a starting point for your own due diligence.
For timber, check chain of custodyFSC or PEFC chain of custody certification traces timber from forest to product. Without it, origin claims for timber are difficult to verify independently.

Watch out. Be sceptical of vague claims like 'sustainably sourced' or 'responsibly made' without specific evidence. Genuine sustainable sourcing comes with documentation - certificates, audit reports, or verifiable supply chain data.

Red flags to watch for

Not every misleading claim is intentional. Some suppliers genuinely believe their products are sustainable but lack the evidence to prove it. These red flags help you distinguish between strong and weak claims.

Unverifiable certificates

If you can't check it against a public registry, treat it with caution.

Vague origin claims

'Sourced from Europe' without naming countries or factories.

No chain of custody

For timber products, absence of CoC means the source can't be traced.

Recycled content without method

A percentage without stating pre/post-consumer or verification basis.

Defensive responses

A supplier confident in their credentials will share evidence readily.

Unknown EPD programme

EPDs not registered with a recognised programme operator (IBU, BRE, EPD International).

Browse the libraryVerified vs Unverified Data