Scope 3 Carbon Footprint: how to prioritize, refine, and collect your data without getting overwhelmed?

If you've already read our comprehensive A-Z guide to Carbon Footprinting, you know that unlike Scope 3, calculating emissions related to your office electricity consumption (Scope 2) or company vehicle fuel (Scope 1) is relatively straightforward. It often just requires compiling a few invoices.

However, assessing this notorious Scope 3 often turns out to be a real headache. Representing the vast majority of a company's total footprint, it encompasses your entire value chain. How do you calculate everything? Should you badger your suppliers? How do you measure the exact impact of a purchase?

The good news is that a robust carbon footprint is built in stages, without trying to measure everything from the first year. Discover our three-step method to master your Scope 3: prioritize your categories, avoid the trap of monetary ratios, and engage your suppliers and partners.

‍

Step 1: How to prioritize among the 15 Scope 3 categories?

The GHG Protocol, the international reference standard, divides Scope 3 into 15 distinct categories.

The GHG Protocol, the international reference standard, divides Scope 3 into 15 distinct categories. These are referred to as "indirect emissions" because they originate from sources you don't directly control, but which are a consequence of your activities. This value chain is separated into two blocks:

• Upstream emissions (categories 1 to 8): everything generated to operate your business (purchases of goods and services, upstream transport, employee travel, waste, etc.).
• Downstream emissions (categories 9 to 15): everything concerning the impact of your products once they leave your premises (transport to customers, use of sold products, end-of-life, investments, etc.).

The 80/20 rule applied to carbon footprinting

The first step is to accept that absolute exhaustiveness is an illusion at the outset. Your goal is to identify, a priori, the most emissive items in your value chain. Often, Pareto's law applies perfectly to carbon accounting: 20% of your activity categories generate 80% of your emissions.

For a service company, the largest source of emissions will likely be the "Purchases of goods and services" category. For a manufacturing company, it will probably be the purchase of raw materials and the use of products sold.

How to conduct a high-level preliminary assessment?

Before delving into complex data research, create an initial mapping based on the nature of your activities, your industry, and your major financial expenditures.
Use the overall data you already have (such as your General Ledger or production volumes) to identify your main expenditure items or core activities that will, most likely, be significant sources of emissions.

This initial deductive screening will allow you to temporarily set aside secondary activities to focus your energy and data collection resources on your most impactful areas. It is on these key priorities that your reduction strategy will have a real impact later on.

‍

Step 2: Monetary Ratios vs. Physical Data: How to Improve Accuracy?

Once your priority categories are identified, the question of the calculation method arises. This is where many companies fall into the trap of convenience: the exclusive use of monetary ratios.

Why do monetary ratios undermine your reduction efforts?

The monetary ratio is a method that involves translating a financial expenditure into CO2 emissions. The formula is simple: €1 spent in a given sector of activity = X kg of CO2 equivalent.

While this method can prove very useful and practical, it becomes a major obstacle when you seek to reduce your emissions. Why?

• The inflation effect: If the price of steel or your software licenses increases by 10%, your carbon footprint will mathematically increase by 10%... even if you purchased exactly the same physical quantity!
• The invisibility of eco-design: If you decide to purchase a recycled material, which is often slightly more expensive to purchase than new, the monetary calculation will inflate your carbon footprint, thus penalizing your initiative.

How to successfully transition to physical data?

To manage a true decarbonization trajectory, you absolutely must refine your method and migrate towards physical data as much as possible.

Instead of saying "I spent €10,000 on transport," you should aim to obtain the data: "I had 5 tons of goods transported 800 kilometers by truck." By cross-referencing this physical data with an emission factor from a recognized database (such as the ADEME's Base Empreinte), you get a precise and actionable result.

‍

Step 3: How to smoothly engage your suppliers in data collection?

To obtain precise physical data on your purchases, you will inevitably need to go beyond your company's walls and question your suppliers. However, keep in mind that your suppliers are likely already very busy. The challenge, therefore, is to collect this information without adding to their workload.

Intelligently target your key partners

Don't send a carbon questionnaire to all 500 of your suppliers. Apply the prioritization rule again: identify the top 20% of your suppliers who represent the majority of your spending or strategic volumes. These are the ones you should engage with first.

4 tips for smooth and efficient collection

The goal is to retrieve primary data (your supplier's own carbon footprint for the product they sell you), often formalized through an LCA (Life Cycle Assessment), an EPD (Environmental Product Declaration), or a PCF (Product Carbon Footprint):

1. Educate, don't inspect: Explain why you are requesting this data (your own CSRD or regulatory requirements) and demonstrate that it's a collaborative effort.
2. Standardize your requests: Avoid complex 40-page Excel files. Use simplified, standardized, and easy-to-fill questionnaires.
3. Accept approximation initially: If a supplier doesn't know the exact carbon footprint of the product they sell you, initially accept simple physical data (e.g., material weight, country of origin, kilometers traveled) to perform the calculation yourself.
4. Reward good performers: Integrate environmental criteria into your future calls for tenders to reward suppliers who can provide clear physical data.

‍

Conclusion

Scope 3 calculation is not a static accounting exercise; it's a continuous improvement process. In the first year, your assessment will likely be dominated by macroscopic estimates and monetary ratios. This is normal. The goal in subsequent years will be to "clean up" this data by gradually replacing euros with tons, liters, or kilowatt-hours, through smart collaboration with your strategic suppliers.

Unsure where to begin refining your Scope 3?
Spreadsheets quickly reach their limits when it comes to engaging your stakeholders. The Kiosk platform allows you to automate certain tasks and facilitate primary data collection from your suppliers. Take it to the next level and turn your carbon assessment into a real management tool.