Getting scope 3 data out of a supplier takes three things: asking for a specific number instead of "your carbon footprint", sending the request from procurement rather than sustainability, and providing a closed response format. Everything else is prioritisation: primary data only from the suppliers that concentrate your spend, spend factors for the long tail.
What scope 3 data should you actually ask a supplier for?
It depends on the calculation method you plan to use. The GHG Protocol Technical Guidance for Calculating Scope 3 Emissions ranks the category 1 methods (purchased goods and services) from most to least specific, and each one needs a different input. Asking for the wrong input is the most common reason a data campaign goes unanswered.
| Method | What you ask the supplier for | When to use it |
|---|---|---|
| Supplier-specific | Cradle-to-gate product carbon footprint in kg CO2e per unit, stating the standard applied and the year | Critical raw materials and components, few suppliers, high spend |
| Hybrid | The supplier's actual energy and emissions data, filled in with secondary data where gaps remain | Key suppliers that do not yet have a product footprint |
| Average-data | Quantity purchased in kilograms, litres or units | Homogeneous purchases with sector factors available |
| Spend-based | Nothing, your own ledger has it: euros per purchasing category | Long tail of suppliers and first inventory year |
The GHG Protocol also recommends that, where secondary data is used, companies prefer sources that are internationally recognised, published by national governments or peer reviewed. Before you design the campaign, map every purchase against the 15 scope 3 categories of the GHG Protocol, because the data you need changes completely from one category to the next.
What to ask for in each scope 3 category
| Category | Ideal primary data | Acceptable fallback |
|---|---|---|
| 1. Purchased goods and services | kg CO2e per product unit, with standard and reporting period | Kilograms purchased times a sector factor, or euros times a spend factor |
| 2. Capital goods | Footprint of the equipment or installation delivered | Investment amount times a spend factor |
| 4. Upstream transportation and distribution | Tonne-kilometres by mode and vehicle type | Carrier fuel litres, or freight spend |
| 5. Waste generated in operations | Tonnes by waste type and treatment route | Estimate from waste transfer documents |
| 6. Business travel | Trips, mode and distance from the travel agency | Spend by trip type |
| 9. Downstream transportation and distribution | Tonne-kilometres from the logistics operator | Distribution spend |
| 12. End-of-life treatment of sold products | Material composition and disposal route | Sector average by material |
If you are still deciding what belongs where, start from the difference between scope 1, 2 and 3 emissions and from this guide to starting your scope 3 emissions journey.
How many suppliers should you contact?
Far fewer than you think. The GHG Protocol Scope 3 Standard does not require primary data from your whole supplier base. It asks you to prioritise activities by their estimated magnitude of emissions, their financial significance (spend upstream, revenue downstream), how much influence you have over the activity, how much they contribute to your risk exposure, stakeholder concern, and whatever sector guidance flags as significant.
A working rule: rank suppliers by annual spend, mark the ones that account for the bulk of spend in your material categories, and restrict the primary data campaign to that group. For everyone else, use spend factors and document it. Twenty good responses beat two hundred unanswered requests.
How much information can you legally demand from a small supplier?
Since 2026 there is an explicit ceiling. Directive (EU) 2026/470, published in the Official Journal on 26 February 2026 and in force since 18 March 2026, introduces the value chain cap: a company subject to sustainability reporting cannot require a company in its value chain with fewer than 1,000 employees on average to provide more information than the voluntary standard covers, and that protected company has the right to refuse anything beyond it.
On 3 July 2026 the European Commission adopted the delegated acts containing the revised ESRS and that voluntary reporting standard for smaller companies, built on the VSME that EFRAG published in December 2024 and that the Commission had already endorsed through Recommendation (EU) 2025/1710 of 30 July 2025. In the VSME basic module, disclosure B3 covers total energy consumption, scope 1 emissions, location-based scope 2 emissions and GHG intensity over turnover. Scope 3 sits outside the basic module.
The practical consequence: asking a small supplier for scope 1, scope 2 and energy consumption is squarely inside the cap and you can point to the standard when you ask. Asking for a verified product footprint for every reference is outside it, and they can decline. Worth explaining to suppliers directly, because it is the same ground covered by the CSRD trickle-down effect on SMEs in the supply chain and the simplified standards for SMEs.
Email template to request emissions data from a supplier
Written to be sent from procurement, copying the usual commercial contact. Replace anything in brackets.
Subject: [Your company]: 2025 emissions data for your supplier record
Body:
Hi [name],
We are closing [your company]'s 2025 emissions inventory and we need to include data from the suppliers we work with most. [Supplier] is one of them.
We are asking for four numbers. If you do not have all of them, send what you have and we will flag the rest as our own estimate.
1. Total energy consumption in 2025, in MWh (electricity, gas and fuels).
2. Scope 1 emissions in tonnes of CO2e for 2025.
3. Scope 2 emissions in tonnes of CO2e for 2025, stating whether it is location-based or market-based.
4. 2025 turnover, only so we can calculate intensity. If you would rather not share it, tell us and we will use your sales to us instead.
If you also have a footprint for the products you supply us (kg CO2e per unit, cradle to gate), it saves us estimating and improves data quality for both sides. Tell us which standard you followed and the year of the calculation.
You can reply to this email with the numbers in the body, or use the attached template. Deadline: [date, three to four weeks out].
Why we are asking: our customers and our bank now ask us for the emissions breakdown of our supply chain, and suppliers who provide their own data appear with their real figure instead of a sector average. We do not need a report, a certificate or an audit. Just those numbers.
If someone else at [supplier] owns this data, forward this email and tell us who to follow up with.
Thanks,
[Name]
[Job title], procurement
[Phone]
What fields should the questionnaire have?
The shorter the better. A supplier questionnaire that takes under fifteen minutes has a completely different response profile to a forty question form. Minimum fields:
- Legal name, tax ID and contact person for environmental data.
- Reporting year the data refers to.
- Electricity consumption in MWh and the share backed by renewable guarantees of origin.
- Natural gas and other fuel consumption, in MWh or physical units.
- Scope 1 and scope 2 emissions in tCO2e, with the scope 2 method stated.
- Scope 3 total and categories included, if already calculated.
- Product footprint per reference supplied, if it exists: value, functional unit, standard and life cycle boundary.
- Whether the calculation has been third-party verified, and by whom.
- Reduction targets, if any, with base year and target year.
Add a "not available" box to every field. A form that forces every cell gets abandoned; one that lets a supplier admit a gap tells you something useful about their maturity.
How do you phase a supplier data campaign?
| Phase | What you do | Who signs it |
|---|---|---|
| Preparation | Pull spend by supplier from the ERP, segment by scope 3 category and pick who enters the campaign | Sustainability and procurement |
| Pilot | Send to five to ten friendly suppliers, measure how long they take and what they ask, then fix the questionnaire | Procurement |
| Main send | Personalised email with a deadline and the questionnaire, one per supplier | Procurement |
| Reminder | Ten days later, reply on the same thread rather than a new email | Procurement |
| Call | Only the highest spend suppliers who have not replied | Category buyer |
| Close | Consolidate responses, fill gaps with proxies and document the origin of every figure | Sustainability |
Two details move the numbers. First, who signs: an email from the buyer who manages the contract gets read, one from a generic sustainability inbox gets filed. Second, timing: sending requests in August or during accounts close guarantees silence.
What do you do about suppliers who never reply?
You fill the gap and you say so. That is the short answer, and it is exactly what the standard anticipates. The GHG Protocol requires you to describe the types and sources of data used, to disclose the percentage of emissions calculated using data obtained from suppliers, and to describe the data quality of what you report. An inventory with 20% primary data and that figure disclosed is sound; one that looks like primary data where there is estimation is not.
Gap-filling options, best to worst: sector average applied to physical activity data, a comparable supplier in the same purchasing group, extrapolation from another site or year of the same supplier, and a spend factor over invoiced euros. That hierarchy lets you close the inventory and then replace estimates with real data where the error hurts most. Automating classification and emission factor assignment removes most of the manual work, which is the point of using AI to calculate scope 3 from supplier data.
Mistakes that get your request ignored
- Asking for "your carbon footprint" with no scope, year or unit. Nobody knows what to send.
- Sending a sixty row spreadsheet with locked tabs to a ten person supplier.
- Giving no deadline, or a three day one.
- Demanding certificates or verification you do not need for your own calculation.
- Not explaining what the data is for or what the supplier gets out of it.
- Sending from an inbox with no human name behind it.
- Restarting the campaign from scratch every year instead of reusing last year's answers.
- Ignoring the value chain cap and demanding more from an SME than the voluntary standard covers.
Frequently asked questions
Is scope 3 mandatory in Spain?
Not as a general rule. Spain's Royal Decree 214/2025 obliges companies within its scope to calculate their carbon footprint annually and to have a reduction plan, but it requires scope 1 and scope 2 and leaves scope 3 voluntary. Whether your large customers, your bank or a public tender ask for it is a separate matter.
Can I refuse to provide data if I am the supplier?
If you have fewer than 1,000 employees on average, you can refuse information beyond what the European voluntary standard covers, under Directive (EU) 2026/470. That said, sharing scope 1 and 2 usually works in your favour: it replaces a sector average with your real figure, which is almost always better.
How much primary data do I need for the calculation to be valid?
The Scope 3 Standard in force sets no minimum percentage. What it does require is disclosing what share of emissions was calculated with data obtained from suppliers. The GHG Protocol is revising its whole corporate suite, scope 3 included, so this is worth following, but as things stand there is no mandatory minimum threshold.
Is a platform better than email for collecting the data?
Only if the supplier already uses it. Sector initiatives such as Together for Sustainability in chemicals, Catena-X in automotive, or product footprint exchange under the WBCSD PACT Methodology work well when the whole chain is inside. If your supplier is not, a new platform is one more barrier and a short email questionnaire performs better.
What if the supplier sends a figure that looks wrong?
Ask for the breakdown by source and the year, and compare it against the sector factor you would have used. If the gap is an order of magnitude, it is almost always a unit error (kWh versus MWh, kg versus tonnes) or a misallocated scope. Document the check: it is part of the data quality you will have to describe.
Collecting supply chain data is mostly a process and traceability problem, not a formula problem. To see how the request, the response and the calculation live in one place, with an audit trail for every figure, take a look at Manglai's carbon footprint software and how it works for supply chain managers.
