What Data Customers Actually Need for Scope 3 Reporting

Your customer has asked for carbon data. The request mentions Scope 3, emissions factors, CO2 equivalents, and possibly specific GHG Protocol categories. You supply them with products or services, not climate science, and now you need to figure out what they actually want.

The short answer: they need numbers that represent the carbon footprint of what you sell them. The longer answer involves understanding why they need it, what format works, and how much effort this really requires from you.

Why Customers Are Asking Now

The Corporate Sustainability Reporting Directive (CSRD) requires roughly 50,000 EU companies to report their full greenhouse gas emissions, including Scope 3. Scope 3 covers everything in their value chain that they don't directly control. That includes you.

Each of those 50,000 companies buys from dozens or hundreds of suppliers. Every supplier contributes to their Scope 3 footprint. When they report to auditors, they need data from their supply chain to back it up. This is not optional curiosity. It is regulatory compliance, and the deadlines are already rolling in.

If you supply to large or mid-sized European companies, expect these requests to become annual. Companies reporting under CSRD in 2026 need supplier data covering 2025. Those starting in 2027 will need your 2026 data. The wave is building, not receding.

The 15 Scope 3 Categories and Where You Fit

The GHG Protocol defines 15 categories of Scope 3 emissions, split between upstream (supply chain) and downstream (product use, distribution). Here are the ones that matter most for suppliers:

Category 1: Purchased Goods and Services. This is where you appear in your customer's report. The emissions from producing and delivering what you sell them land here. For most suppliers, this is the only category you need to worry about.

Category 2: Capital Goods. If you sell equipment, machinery, or other capital assets, your products fall here instead.

Category 4: Upstream Transportation. If you arrange transport of goods to your customer, those logistics emissions may be relevant.

Category 9: Downstream Transportation. If your customer handles transport, these emissions sit in their Category 9 rather than your responsibility.

The remaining categories cover things like business travel, employee commuting, waste, leased assets, and investments. These are your customer's problem to calculate for their own operations, not something they need from you.

Focus your effort on Category 1. That is the data request behind almost every supplier Scope 3 email.

What Customers Actually Need from You

Requests vary in specificity, but they converge on a few core data points. Here is what they are looking for, ranked from ideal to minimum.

Total Emissions in Tonnes CO2e

This is the gold standard. A single number representing the total greenhouse gas emissions associated with what you supplied, expressed in tonnes of carbon dioxide equivalent (CO2e). If you can provide this with a documented methodology, most customers will be satisfied.

Calculating this requires multiplying your activity data by appropriate emission factors. If you have never done this, the carbon footprint calculation guide for manufacturers walks through the process.

Activity Data

If you cannot calculate emissions yourself, provide the raw inputs and let your customer's sustainability team do the math. Useful activity data includes:

• Electricity consumption in kWh (with your grid region or country)
• Natural gas consumption in kWh or cubic meters
• Fuel consumption in liters (diesel, petrol, LPG)
• Material inputs by weight (tonnes of steel, plastic, chemicals)
• Production volumes (units produced, tonnes shipped)
• Water consumption in cubic meters
• Waste generated in tonnes, by disposal method

This is the practical minimum. Customers with mature sustainability programs have tools that convert activity data into emissions using standard factors. Providing clean activity data is genuinely useful, even without a final CO2e number.

For guidance on gathering energy data specifically, see the energy consumption tracking guide.

Emission Factors and Methodology

When you do calculate emissions, document which emission factors you used and where they came from. Customers and their auditors want to know:

• Which emission factor database (DEFRA, IPCC, national grid factors)
• The reporting year the factors apply to
• Whether you used location-based or market-based accounting for electricity
• What is included and excluded from the calculation boundary
• Any assumptions or estimates you made

A number without methodology is hard for auditors to accept. A clearly documented estimate is far more useful than an undocumented precise-looking figure.

Product-Level vs Organization-Level Data

Some customers want the emissions for the specific product they buy from you. Others accept organization-level data allocated by revenue or volume. Ask which they need.

Product-level carbon data (sometimes called a product carbon footprint or PCF) requires understanding the energy, materials, and processes that go into a specific item. This is more work but more accurate for their Category 1 reporting.

Organization-level data divided by revenue share is simpler. If a customer represents 15% of your revenue, they take 15% of your total emissions. This is a reasonable starting point when product-level data is not available.

The Data Quality Hierarchy

Customers and reporting frameworks rank supplier data quality in a clear hierarchy:

Supplier-specific data (best). You calculate your actual emissions based on your real energy use, fuel consumption, and material inputs. This is what they want.

Average data (acceptable). Industry averages or product-category emission factors applied to quantities purchased. Better than nothing, but less accurate.

Spend-based estimates (last resort). Your customer takes what they paid you and multiplies by an average emissions-per-euro factor for your industry. This is the least accurate approach and the one they use when you give them nothing.

Here is the critical insight: when you provide no data, your customer does not leave a blank. They estimate using spend-based factors, which almost always overstate your emissions. Providing real data usually makes your carbon footprint look better than the default assumption, because industry averages are dragged up by the least efficient producers.

Giving your customer actual data is not just good practice. It is in your interest.

What Format They Want

Customers rarely want a free-form email. The most common formats:

Their own spreadsheet template. Many companies send a supplier data collection template. Fill it in exactly as requested. Do not improvise your own format when they have provided one.

CDP Supply Chain questionnaire. Large multinationals often route Scope 3 data collection through CDP. This is a structured online platform with specific fields for each data point.

EcoVadis scorecard. Some customers use EcoVadis scores as a proxy for supplier environmental data. Your EcoVadis carbon section feeds their Scope 3 calculations.

Custom sustainability portals. Companies like SAP Ariba, IntegrityNext, or Ecodesk have built-in supplier sustainability modules. You may be asked to enter data directly into a procurement platform.

Simple spreadsheet. Smaller customers or those early in their Scope 3 journey will accept a clean spreadsheet with documented data. When no template is provided, structure it as: reporting period, emission source, activity data, emission factor, calculated emissions, methodology notes.

If you received a Scope 3 questionnaire from a customer, respond in whatever format they sent. Making it easy for them to process your data matters almost as much as the data itself.

Your Minimum Viable Response

You have never tracked emissions. The deadline is soon. Here is what you can realistically provide today:

1. Pull 12 months of electricity bills. Sum total kWh consumed. Note your country.
2. Pull 12 months of gas bills. Sum total kWh or cubic meters of natural gas.
3. Estimate fuel consumption. Liters of diesel or petrol for company vehicles and equipment.
4. List major materials purchased. Tonnes of key inputs (metals, plastics, chemicals, packaging).
5. State your production volume. Units produced or tonnes shipped to this customer.
6. Acknowledge gaps. Be explicit about what is estimated, what is missing, and what you plan to improve.

Send this as activity data with a note explaining that formal emissions calculations are in development. This is already more useful than what most suppliers provide.

Leveling Up Over Time

Scope 3 data quality should improve each year. A realistic progression:

Year 1: Activity data only. Energy bills, fuel records, material quantities. Customer applies their own emission factors.

Year 2: Calculated emissions. You apply recognized emission factors (DEFRA, national databases) to your activity data and report in tonnes CO2e. Methodology documented.

Year 3: Verified and refined. Product-level carbon footprints where feasible. Third-party verification for key data points. Year-over-year comparison showing trends.

No customer expects you to jump to year 3 immediately. They expect progress. Providing activity data this year and calculated emissions next year demonstrates exactly the trajectory they want to see.

Why This Is a Competitive Advantage

Procurement teams managing hundreds of suppliers notice who responds and who does not. When two suppliers offer comparable products at similar prices, the one who provides clean carbon data on time makes the procurement team's life easier. The one who ignores the request creates compliance gaps that someone has to chase.

You do not need the lowest carbon footprint in your industry. You need a credible, documented, timely response. That alone puts you ahead of the majority of suppliers, because most are still ignoring these requests or sending vague policy statements instead of numbers.

The bar is low. Clear it.