Your Client Is Asking for Scope 3 Emissions Data — Here's What That Actually Means
Why Are Clients Asking for Scope 3 Specifically?
If a client's questionnaire specifically mentions Scope 3, they are dealing with CSRD — the EU's Corporate Sustainability Reporting Directive. Under CSRD, large companies must disclose their full Scope 3 supply chain emissions in their annual sustainability reports. To do that, they need the operational emissions data of every significant supplier. You are one of those suppliers.
Scope 3 is the category that covers everything outside your own operations — and it represents 70–90% of most large companies' total footprint. That is why your client cares so much about it.
What Scope 3 Is (And What It Isn't)
There are 15 Scope 3 categories in the GHG Protocol. When your client asks for your "Scope 3 emissions," they typically mean your operational Scope 3 — the indirect emissions generated by running your business that are not captured in Scope 1 or 2. These are:
| Category | What it covers | How to estimate it |
|---|---|---|
| Category 3 (WTT) | Upstream extraction of fuels you burn | Auto-calculated from your Scope 1 data |
| Category 5 (Waste) | Waste generated at your premises | Waste contractor invoice × DEFRA factors |
| Category 6 (Travel) | Business flights, hotels, rail | Expense reports × distance factors |
| Category 7 (Commuting) | Staff travel to and from work | Headcount × commute distance × 220 days |
They are not asking you to calculate *their* Scope 3 Category 1 (the emissions embedded in the products or services you provide to them). That is their job, using your Scope 1+2+3 data as one input.
What the Questionnaire Field Is Actually Asking For
When a questionnaire says "please provide your Scope 3 emissions," they want:
- A tCO2e figure for your total Scope 3 (or key categories)
- The methodology you used to calculate it
- The reporting year it covers
They do not need a breakdown by all 15 categories. Categories 3, 5, 6, and 7 represent the material Scope 3 for most non-agricultural SMEs.
A Worked Example for a 20-Person Service Business
| Category | Data | Calculation | Result |
|---|---|---|---|
| Category 3 (WTT) | 2,000 m³ natural gas | 2,000 × 0.376 ÷ 1,000 | 0.75 tCO2e |
| Category 5 (Waste) | 2 tonnes landfill | 2,000 × 0.459 ÷ 1,000 | 0.92 tCO2e |
| Category 6 (Travel) | 4 short-haul return flights (2,000 km each) | 8,000 × 0.255 ÷ 1,000 | 2.04 tCO2e |
| Category 7 (Commuting) | 20 employees, 20 km avg round trip, 220 days, 60% car | 20 × 20 × 220 × 0.170 ÷ 1,000 × 0.6 | 8.98 tCO2e |
| Total Scope 3 | 12.7 tCO2e |
For a 20-person office business, a Scope 3 figure in the range of 10–20 tCO2e is entirely normal and will not raise concerns from buyers.
Why You Cannot Just Leave Scope 3 Blank
Some suppliers fill in Scope 1 and 2 but leave Scope 3 as zero or blank. Procurement systems flag this because it is implausible — every business that has employees who commute and travels for work has non-zero Scope 3. A blank Scope 3 field triggers a manual review request or an automatic quality flag in the buyer's system.
An honest estimate — even if imprecise — is always better than a zero or blank.
The Fastest Way to Calculate Your Scope 3
DeCarbonOPS automatically calculates all four material Scope 3 categories from the data you enter. Category 3 (WTT) is derived from your Scope 1 fuel inputs with no extra entry needed. You enter your waste estimate, travel data, and commuting inputs, and the platform produces a Scope 3 total in tCO2e ready to paste into your questionnaire — along with a Carbon Passport verification URL the buyer can check.
Frequently Asked Questions
When a client asks for my Scope 3, which categories do they mean?
For most supplier questionnaires, 'your Scope 3' means your operational upstream Scope 3: Category 3 (well-to-tank emissions from fuels you burn), Category 5 (waste at your premises), Category 6 (business travel), and Category 7 (employee commuting). They are not asking you to calculate the emissions embedded in your products or services — that is their Scope 3 Category 1, which they estimate separately.
Can I report Scope 3 as zero if I have no business travel?
Not if you have employees who commute. Even if you have no business flights or business travel, your employee commuting generates non-zero Scope 3 Category 7. Reporting Scope 3 as zero when you have staff triggers a quality flag in procurement systems. Estimate your commuting emissions: employees × average commute km round trip × 220 days × 0.170 kgCO2e/km (car) ÷ 1,000.
What is WTT and why is it in my Scope 3?
WTT stands for Well-to-Tank — the upstream emissions from extracting, refining, and transporting the fuels you burn in Scope 1. For every litre of diesel you combust, additional emissions were generated to get that diesel from an oil field to your fuel tank. DEFRA 2023 WTT factors: natural gas 0.376 kgCO2e/m³, diesel 0.641 kgCO2e/litre. DeCarbonOPS calculates WTT automatically from your Scope 1 inputs.
Is there a maximum Scope 3 total that would raise concerns with a buyer?
No maximum, but context matters. A 10-person service firm with 40 tCO2e Scope 3 dominated by commuting and flights is entirely normal. A manufacturing company with 50 employees and only 5 tCO2e Scope 3 may prompt a follow-up question about methodology coverage. The figures should be plausible for your business type — not artificially low.
What is the Scope 3 total for a typical 20-person EU SME?
For a 20-person office-based EU SME: Category 3 WTT (5–10 tCO2e from gas and fuel combustion), Category 5 waste (1–3 tCO2e), Category 6 travel (5–20 tCO2e depending on travel intensity), Category 7 commuting (8–20 tCO2e). Total Scope 3 typically 15–50 tCO2e for a service business and 30–100 tCO2e for a light manufacturing company. These are well within normal ranges that procurement teams expect.
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