Asking suppliers for carbon data works. Small businesses that were asked for carbon footprint data by a customer or in a tender were 3.9 times more likely to make net zero a high priority than those that weren't, according to the British Business Bank. And companies that actively engage their suppliers are nine times more likely to achieve their Scope 3 targets , according to EcoVadis and BCG — yet only one in three do.
So the problem isn't that buyers ask. It's how they ask: each customer with its own questionnaire, its own platform, its own format and its own deadline, for information that is mostly the same.
The Same Questions, Asked a Hundred Different Ways
The volume is significant. Through CDP's Supply Chain programme alone, more than 270 major buyers asked around 45,000 suppliers to disclose in 2025 . On top of that sit the in-house questionnaires, supplier portals and rating platforms each large customer runs for itself.
The OECD has described the pattern directly: many financial institutions and large enterprises develop their own methodologies and sustainability questionnaires for SME clients 13/FINAL/en/pdf), and in the absence of standardised, interoperable frameworks, these demands "will continue to pose a challenge".
The burden doesn't fall evenly. In the UK, 9% of SMEs overall had been asked for carbon footprint data in the previous 12 months — but 37% of medium-sized businesses had . Those are exactly the mid-sized suppliers that sell to many large customers at once, usually without a dedicated sustainability team.
Why Fragmented Requests Hurt the Buyer, Too
It is tempting to treat questionnaire fatigue as the supplier's problem. It isn't. The Science Based Targets initiative's own supplier engagement guidance makes the link explicit: suppliers are likely facing a variety of similar requests from their customers, and choosing a solution that addresses survey burden "increases the probability of collecting more data of a higher quality" .
Fragmentation costs buyers in three ways:
1. Less data, and worse data. A supplier answering the same question five ways for five customers answers fast rather than carefully, or not at all. What comes back is hard to compare across suppliers and hard to defend in an audit.
2. Nothing can be automated. Answers can only be produced at scale — straight from a supplier's existing systems — if the questions are standard. Every bespoke format means manual work on both sides.
3. Duplicated effort across the chain. In automotive, Catena-X describes the result of missing common methods and incompatible tools as inaccurate footprints, limited reduction potential "and duplicated efforts throughout the value chain" .
In the EU, Regulation Now Draws the Line
Aligning on a common core is no longer just good manners in Europe. The Omnibus I Directive introduced a "value chain cap": companies reporting under CSRD may not require companies in their value chain with 1,000 employees or fewer to provide more sustainability information than the EU's voluntary reporting standard , adopted as Commission Delegated Regulation (EU) 2026/1560 .
Buyers can still ask for more, but they must say which items go beyond the cap and tell the supplier it has a statutory right to decline. The Commission is explicit that companies are not meant to ask for the maximum the cap allows, and the delegated regulation says reporting companies should request only what they need. Two limits matter: the cap covers requests made for CSRD reporting, not for risk management or due diligence, and it restricts what buyers can require , not what suppliers may choose to share.
In practice, the EU voluntary standard becomes the default common core for supplier requests in Europe. A questionnaire that goes far beyond it now carries legal friction as well as supplier fatigue.
Industries That Already Ask With One Voice
Several sectors have already moved from collaboration to coordination:
- Chemicals. Members of Together for Sustainability share assessment and audit results among themselves, so suppliers receive fewer redundant requests , and use a common Product Carbon Footprint Guideline.
- Automotive questionnaires. Drive Sustainability's self-assessment questionnaire lets suppliers complete a single questionnaire that is shared with multiple buyers .
- Automotive product data. In a Catena-X pilot, Micron passed primary product carbon footprint data to Flex, which used it in its own footprint and passed it on to Ford — each on the IT system of its choice. Using primary data instead of industry averages, the footprint values came out 46% lower .
- Across industries. WBCSD's Partnership for Carbon Transparency (PACT) standardises the calculation and exchange of supplier-specific product carbon footprints , so one footprint can travel to many customers.
Aligned Doesn't Mean Identical
There is a fair objection. SBTi's guidance notes the trade-off itself: standardised questionnaires "may not perfectly meet the company's data needs and tend to be more extensive" . Its advice for companies that keep their own questionnaire is to align the questions with commonly used standardised surveys, so suppliers can reuse what they already collect.
The way through is layers, not one giant form. Most suppliers need only the common core. A few matter far more: supply chain emissions are on average 21 times higher than direct emissions, and up to 50% of supplier emissions can be cut cost-neutrally . That is where bespoke effort belongs.
| Supplier group | What to ask | How to ask it |
|---|---|---|
| The long tail | The common core: emissions, targets, energy | A shared standard (the EU voluntary standard, CDP or your industry's questionnaire); accept what suppliers already publish |
| Category-critical suppliers | The core plus category data, such as product footprints | Your industry's methodology and an exchange standard such as PACT or Catena-X |
| Top emitters | Joint reduction plans | Direct conversations, site visits and commercial terms, not questionnaires |
Five Things to Do This Quarter
- Audit your current asks. Map every question you send suppliers against the EU voluntary standard and the main disclosure frameworks. Cut anything you don't use in a decision or a report.
- Accept what already exists. If a supplier already discloses through CDP, an industry scheme or the voluntary standard, take that instead of your own form.
- Flag anything extra. If you need more than the common core, explain what it is for — and in the EU, say that it goes beyond the value chain cap.
- Join before you build. Use your industry's initiative and exchange standards rather than launching another proprietary questionnaire or portal.
- Move the saved time to your top emitters. Spend it on conversations and joint plans with the few suppliers that drive most of your footprint.
Where Simple. Fits
The cheapest supplier request is the one you never send. Much of a company's Scope 3 footprint can be built from documents it already holds: the invoices and bills of materials behind every purchase. That is what we built Simple. to do. It reads supplier invoices line by line and calculates the footprint of each purchase with the most specific method available — a verified EPD, an activity-based factor, or a spend-based fallback — labelled on every line, so you can see how solid each number is.
For buyers, that means the questions you send suppliers can shrink to what only they know, such as their reduction plans. For suppliers fielding requests from several customers, it means answering from your own invoices instead of starting from scratch each time.
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This article draws on the British Business Bank's SMEs and Net Zero 2025 report, the OECD's work on SME sustainability reporting, SBTi's supplier engagement guidance, the EcoVadis and BCG Carbon Action Report 2025, CDP's 2025 disclosure data, Catena-X and the European Commission's guidance on the CSRD value chain cap.
