Scope 3 data that survives assurance.
ESRS E1 asks for value-chain emissions you can evidence, and most of that number belongs to your suppliers. In CarbonSig you model your products and your suppliers model theirs — then an independent third party verifies them in the platform, so the figures behind your disclosure trace back to a model instead of an average.
- Product-level, node by node
- Supplier data as attestations, not spreadsheets
- Independently verified, in the platform
An illustrative ESRS E1 Scope 3 line item for purchased goods and services, made up of three supplier products. Hot-rolled steel coil and aluminium billet are Verified on CarbonSig; polymer resin is still self-attested and not yet verified. Supplier footprints arrive as Environmental Attribute Certificates and become inputs in your own model.
What does CSRD assurance mean for Scope 3 product data?
Under CSRD an independent auditor gives assurance on your sustainability statement — limited assurance first, reasonable assurance by 2028 — which raises the bar for the ESRS E1 value-chain figures that come from your suppliers. In CarbonSig those products are modelled and then verified by an independent third party, so each figure traces to a model rather than an average.
Scope 3 is where corporate reporting breaks.
Estimated value-chain data
Spend-based averages and questionnaires
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Supplier emissions are inferred from spend or an industry average.
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Questionnaire answers land in spreadsheets — unverifiable and stale by the time you report.
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A self-attested number is not a verified one, and an auditor will make that distinction.
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Assurance is moving from limited towards reasonable — estimates get harder to stand behind.
Verified product footprints
Modelled node by node, verified in-platform
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Each supplier product carries its own modelled footprint.
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Suppliers send a Carbon Attested Product that traces back to the model behind it.
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An independent, accredited third party has verified the product footprint.
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The evidence sits in one place, node by node, when the questions come.
Build the product, not the report.
A disclosure is a snapshot of something more durable: the model underneath it. Build that once, keep it current, and the reporting falls out of it.
An illustrative product model in the System Builder: a supplier EAC as a Scope 3 input, feeding a forming line whose own Scope 1 combustion hangs below it, producing a coated sheet as the output.
One connected model per product
In the System Builder a product is a set of connected nodes: inputs carrying Scope 2 and Scope 3 emissions, process steps, the direct Scope 1 emissions that happen on your own site, and the output you sell. The result is a footprint you can point at, not a figure someone handed you.
The calculation engine is ISO 14040/44-compliant, and the product footprint is calculated to the GHG Protocol Product Standard and ISO 14067 — the methodologies an assurance provider already recognises.
Next year you rerun the model instead of rebuilding it. New production data, same structure, same traceability — which is what makes a reporting figure comparable year on year.
Ask suppliers once. Get an attestation, not a spreadsheet.
The Relations area, showing requests for carbon attestation to three suppliers: two received and one still pending. A shared attestation becomes an EAC in your account and can then be selected as an input source in your model.
A request, a certificate, an input
Send a Request for Carbon Attestation to a supplier from the Relations area, keep their contacts in the address book, and see who has responded and who has not. It replaces the annual questionnaire chase with a record of what you asked and what came back.
When a supplier shares a Carbon Attested Product with you, it transfers to your account as an EAC — an Environmental Attribute Certificate — and that transfer is irreversible, so the same attestation cannot be counted twice. Suppliers control what they share: private, public or restricted.
You then select that EAC as an input source in your own model, and its emissions carry into your product footprint. The supplier’s work becomes your Scope 3 evidence — with their verification status attached to it, not assumed.
A third party verifies the footprint — in the same platform.
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Step 1
Register the model
Register the finished product model to a locked, read-only snapshot — the immutable copy a verifier reviews, preserved round by round as an audit trail.
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Step 2
A verifier reviews it, round by round
An independent, accredited verifier works in the Verifier Hub, raising findings pinned to the exact node and running revision rounds until they are resolved.
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Step 3
Verified on CarbonSig
The verifier issues a formal opinion and the product carries its verified status — the evidence your disclosure points to when someone asks where a figure came from.
This is verification of a product footprint, and it is performed by an independent accredited third party — CarbonSig hosts the workspace and does not verify. Your CSRD assurance engagement is a separate matter between you and your auditor. What this gives that engagement is evidence: a model behind each figure, rather than an estimate.
Figures your auditor can follow — from a model that outlives the report.
A verified product footprint does not expire with the reporting cycle. The same model that stands behind an ESRS E1 value-chain figure answers the customer asking for a product footprint, the CBAM declaration on the goods you ship into the EU, and the EPD a specifier wants — because they are all asking about the same product.
One model, every standard that asks.
CSRD and Scope 3, answered.
What does CSRD reasonable assurance mean for product data?
CSRD phases assurance in: an independent auditor first gives limited assurance on your sustainability statement, and reasonable assurance is expected by 2028. Limited assurance means the auditor found nothing obviously wrong; reasonable assurance means deeper procedures and a higher level of confidence. For ESRS E1 that raises the bar on value-chain figures — an estimate is harder to defend than a product footprint an independent third party has verified.
Why is Scope 3 the hardest part of a CSRD disclosure?
Because Scope 3 is not yours to measure. It is the emissions of your value chain — purchased goods and services above all — so the number depends on data your suppliers hold. The usual fallback is spend-based or industry-average factors, which are estimates: nobody can trace them to a specific product, and they do not improve when a supplier decarbonises.
How do I get carbon data from my suppliers in CarbonSig?
You send a Request for Carbon Attestation from the Relations area and track who has responded. When a supplier shares a Carbon Attested Product with you, it transfers to your account as an EAC — an Environmental Attribute Certificate — and that transfer is irreversible. You can then select the EAC as an input source in your own model, and its emissions are carried into your product footprint.
Does CarbonSig do our CSRD assurance or write our report?
No. CarbonSig is a pre-verification platform for product-level carbon footprints: you model the product, an independent accredited verifier reviews the registered model in the platform, and the result is “Verified on CarbonSig.” Your CSRD assurance engagement is separate and belongs to your auditor. What CarbonSig gives that engagement is evidence — a traceable model behind each figure rather than an estimate.
Can the same product model also answer CBAM and EPD?
Yes. The product model is the asset, not the report. The same modelled and verified footprint that supports an ESRS E1 value-chain figure also supports a CBAM declaration of embedded emissions and an EPD under EN 15804, because each of those asks the same underlying question about the same product. You model once and report to whichever standard is asking.
Put a verified product footprint behind your Scope 3.
Tell us what you make and what your disclosure needs. We will show you the model, the supplier flow and where the verifier picks it up.