How to Respond to a Supplier Carbon Data Request

You've received an email from a customer — often a large corporate — asking for your “carbon footprint data”, “Scope 1 and 2 emissions”, or asking you to complete a “supplier sustainability questionnaire”. You have a deadline, you're not sure what they need, and you've never done this before.

This guide explains exactly why you're receiving this request, what data your customer needs, and how to get them accurate figures in the shortest possible time.

Why Your Customer Is Asking for This

Since 2024, large EU companies (500+ employees) have been required to report their carbon emissions under the Corporate Sustainability Reporting Directive (CSRD). From 2025, this extends to companies with 250+ employees and €40M+ revenue.

These large companies must report their Scope 3 emissions — which means the emissions caused by their entire supply chain, including their suppliers like you. Your Scope 1 and Scope 2 emissions become part of their Scope 3.

If your customer cannot get verified data from you, they have two options: estimate your emissions using industry averages (which are often unfavourable), or flag you as a non-reporting supplier. Neither outcome is in your interest.

Your Scope 1 and 2 emissions are a line item in your customer's CSRD report. Providing accurate data protects your supplier relationship and avoids being replaced by a supplier who can report.

What Data Is Typically Requested

Most supplier carbon data requests ask for some or all of the following:

Always requested

• Total Scope 1 emissions — your direct emissions from gas boilers, oil heating, company vehicles, and any industrial processes, expressed in tonnes of CO₂ equivalent (tCO₂e)
• Total Scope 2 emissions (location-based)— emissions from your electricity consumption, calculated using your country's grid emission factor, in tCO₂e
• Reporting period — typically the most recent full calendar year or financial year (e.g., January–December 2024)
• Emission factor methodology — which emission factor database was used (DEFRA 2024, IEA, or EPA are the most commonly accepted)

Sometimes requested

• Scope 2 market-based emissions — if you have purchased renewable energy certificates (RECs) or a green electricity tariff, this figure may differ from the location-based figure
• Scope 3 emissions — business travel, employee commuting, and waste. More commonly requested from manufacturing or logistics suppliers where supply chain emissions are material
• Emission intensity — emissions per unit of revenue (tCO₂e per €1M), per employee, or per unit produced. This allows your customer to normalise data across suppliers of different sizes
• Third-party verification — whether your emissions data has been independently verified by a certified carbon accountant or auditor. At SMB level this is rarely required for the first submission

Format variations

Depending on how your customer manages their supply chain data, the request may arrive as:

• A simple email asking for a few figures and a PDF report
• A spreadsheet template to fill in
• A portal request via EcoVadis, Sedex, or SAP Ariba
• A CDP (Carbon Disclosure Project) supply chain questionnaire

In almost all cases, the underlying data needed is the same: Scope 1 and Scope 2 emissions in tCO₂e for a specified period, with methodology noted.

What Happens If You Don't Respond

Ignoring a supplier carbon data request is increasingly risky:

• Your emissions get estimated.Your customer's CSRD report will include your estimated emissions regardless — typically using conservative industry averages that may substantially overstate your actual footprint.
• You get flagged as a high-risk supplier. Companies subject to CSRD are required to engage their supply chain on sustainability matters. Non-responding suppliers are noted in their reporting.
• Contract renewal risk. Procurement teams at large companies are increasingly using ESG criteria in supplier selection. Being unable to provide basic carbon data puts you at a disadvantage against suppliers who can.
• It gets harder over time. The number of companies sending supplier questionnaires will grow significantly through 2025 and 2026. Building the capability to respond now is cheaper than doing it under pressure later.

Step-by-Step: How to Get Your Numbers

Step 1 — Gather your utility bills

You need 12 months of bills for:

• Natural gas (m³ or kWh)
• Heating oil (litres)
• Electricity (kWh) — this appears on every bill
• Company vehicle mileage (km driven per year, from vehicle logs or expenses)

Most businesses can pull this data in 20–30 minutes. If you don't have all bills, estimates from your supplier portal or your accountant's expense data will work for a first submission.

Step 2 — Calculate your emissions

Use the EmissionPlan free calculator — no sign-up required. Enter your gas, oil, electricity, and vehicle data, select your EU country, and get your Scope 1 and Scope 2 totals in tCO₂e instantly. The calculator uses DEFRA 2024 emission factors, which are accepted by the vast majority of large EU companies for supplier reporting purposes.

Step 3 — Add Scope 3 if requested

If your customer has requested Scope 3 data, the calculator also covers:

• Short-haul and long-haul flights (km or estimated from trip records)
• Employee commuting (average distance and mode)
• Waste (kg of general and recycled waste)

For commuting, a quick team survey asking for approximate one-way distance and primary transport mode takes 15 minutes and gives you a usable estimate.

Step 4 — Generate your report

Create a free EmissionPlan account to save your calculation and generate a professional PDF report. The PDF includes:

• Scope 1, 2, and 3 totals in tCO₂e
• Breakdown by emission source
• DEFRA 2024 emission factors cited
• GHG Protocol Corporate Standard and ESRS VSME alignment notes
• Company name, reporting period, and generation date

This PDF is the format most customers and portal systems expect when requesting “your ESG report” or “carbon footprint documentation”.

Step 5 — Respond to your customer

Send your customer the key figures (Scope 1, Scope 2 in tCO₂e, reporting period, methodology) along with the PDF as supporting documentation. A simple covering note:

“Please find our GHG emissions data for the period January–December 2024 attached. Scope 1: [X] tCO₂e. Scope 2 (location-based): [X] tCO₂e. Total: [X] tCO₂e. Calculated using DEFRA 2024 emission factors and GHG Protocol Corporate Standard methodology. A full breakdown is included in the attached PDF report.”

How Quickly Do You Need to Respond?

Most supplier carbon data requests include a deadline of 2–4 weeks. Some procurement portals have shorter windows of 7–10 days.

With the right tool, the entire process — gathering bills, calculating emissions, and generating a PDF — takes under an hour for a typical SMB with straightforward energy use. There is no reason to miss the deadline.

Will You Receive More of These Requests?

Yes. As more large EU companies come into CSRD scope through 2025 and 2026, the volume of supplier sustainability questionnaires will increase significantly. Companies that supply multiple large customers will receive multiple requests — often on different timelines and in different formats.

The SMBs best positioned to handle this are those that have already established an annual carbon measurement process. Once you've done your first calculation, updating it for the following year takes 15–20 minutes — not a day of work.

Create a free EmissionPlan account to save your emissions data, generate your report, and build the annual reporting habit that will protect your supplier relationships for years to come.