If a main contractor's own PPN 06/21 Carbon Reduction Plan and PAS 2080 reporting depend on data from their supply chain, that requirement doesn't stop at their own head office — it flows down to every subcontractor and supplier on the job.
Why this is suddenly landing on subcontractors' desks
A main contractor bidding for public sector work over £5 million now has to submit a Carbon Reduction Plan under PPN 06/21, and increasingly reports whole-project carbon under PAS 2080. Both of those depend on Scope 3 data — the emissions embedded in the materials and services they've bought in — which means the main contractor's own compliance is only as good as the data their supply chain can actually provide.
The practical result: a request that used to be "send us your public liability certificate" now regularly includes carbon figures, waste routes, and sometimes a Biodiversity Net Gain contribution, sent to every tier of subcontractor and material supplier on the job — not just the largest ones.
What's actually being asked for
- Carbon data per material or service — an embodied carbon figure for a supplied material, or a Scope 1/2 estimate for a subcontracted service like plant hire or logistics.
- Waste and disposal routes — particularly for suppliers providing materials with an end-of-life plan attached (see our guide to Site Waste Management Plans).
- A Biodiversity Net Gain contribution, if you're supplying landscaping, planting or habitat-related works — how your part of the job affects the site's overall units.
- Accreditations and policies — ISO 14001, modern slavery statements, environmental policy documents — the paperwork side of the same request.
- A risk self-assessment — increasingly a short questionnaire rather than a document request, scored automatically rather than read line by line.
The most common ask: a one-page carbon/ESG statement per material or service
The single most frequent request isn't a full report — it's a short, standardised statement: what you supply, roughly how much embodied carbon it carries, how it's typically disposed of at end of life, and whether you hold any relevant accreditation. Main contractors ask for this in a consistent format because they need to aggregate dozens or hundreds of these across a project, not read each one individually.
Why the format matters more than the detail. A supplier who answers in the exact structure the main contractor's own reporting tool expects gets used again on the next job. A supplier who sends a long, well-written but differently-structured PDF often gets asked to redo it in the right format anyway — the effort was real, but it didn't land.
Risk scoring — what a "high risk" flag actually means
When a request comes through a scoring tool rather than a human reading a document, "high risk" doesn't necessarily mean you did anything wrong — it usually means one of a few specific gaps:
- No carbon figure provided at all, versus a figure that's simply higher than a competitor's.
- No accreditation on file, even where the underlying practice is sound.
- A disposal route left as "unknown," which scores worse than a genuinely poor route that's at least been declared.
| Gap flagged | What it usually means |
|---|---|
| No carbon figure | Missing data, not necessarily a worse figure than a competitor's |
| No accreditation on file | The practice may be sound — the paperwork just isn't attached |
| Disposal route "unknown" | Scores worse than an honestly declared poor route |
The fix in most cases is answering completely, not necessarily answering differently — an honestly-reported "landfill" disposal route with everything else filled in usually scores better than a mostly-blank questionnaire.
How to respond without derailing your week
- Keep your own figures on file, once. Embodied carbon per unit of your main materials or services, and typical disposal/end-of-life route — worked out once and reused for every request, rather than recalculated from scratch each time.
- Answer the actual questionnaire, not a covering letter. If a main contractor sends a structured form or online questionnaire, use it — a bespoke PDF response usually generates a follow-up asking for the same data in their format anyway.
- Get accreditation documents into one folder. ISO 14001, waste carrier licence, modern slavery statement — the same handful of documents get requested repeatedly across different clients.
- Respond fast. A same-day or next-day response to an ESG questionnaire is a genuine differentiator when a main contractor is choosing between two otherwise-similar quotes.
Common mistakes
- Ignoring the request until it's chased. ESG questionnaires increasingly gate the actual order, not just sit alongside it.
- Guessing at carbon figures. A rough-but-honest estimate, clearly labelled as such, is more useful (and more defensible) than a precise-looking number with no basis.
- Treating every main contractor's request as a one-off. The underlying data is almost always the same; only the format asked for changes.
The upside: winning more of this work, not just complying
Subcontractors who can answer an ESG request same-day, with real figures rather than a placeholder, increasingly get preferred over ones who can't — regardless of price. As more of the supply chain gets asked the same questions, having the answer ready becomes a genuine competitive edge, not just a compliance cost. On the main contractor side, supply chain ESG software turns that same request into an instant, scored answer instead of a chased email thread.