How to collect Scope 3 Purchased Goods data

Why Category 1 comes first

Purchased goods and services usually dwarf site fuel and power, so fixing Category 1 shifts the numbers that matter to procurement and sales. Companies reported supply chain emissions averaging 26 times their operational emissions, and only 15 percent had a supply chain target (CDP and BCG, 2024) (CDP, 2024). That scale is exactly why clients ask for product specific EPDs.

Set the boundary and the clock

Pick a clear reference year, typically the last full fiscal year. List included sites, contract manufacturers, and the product families that hit revenue goals. Document exceptions in a short memo so finance and operations agree and no one reopens the scope midstream.

Map what you buy to what you sell

Start with a consolidated bill of materials for each product family. Tie each input line to a supplier, unit, country of origin, and internal material code. When a part feeds several SKUs, record allocation logic now, not on page 17 of the EPD draft.

Choose a calculation method that fits maturity

Go supplier specific when you can, hybrid when you must, spend based when you have to start fast. The method can vary by line item, but the rules cannot change quarter to quarter.

• Supplier specific: primary data, best for big mass or cost drivers.
• Hybrid: primary data plus background datasets to close gaps.
• Spend based: accounting led, credible for long tails and early baselines, then replace with better data over time. When primary data is missing, use current factors from the EPA GHG Emission Factors Hub and note the version used (EPA, 2025) (EPA GHG Emission Factors Hub, 2025).

Ask suppliers for exactly this

Precision beats volume. For each purchased input, request: mass or quantity per shipment, material or process description, manufacturing location, electricity source if known, recycled content or bio based content, and typical transport leg to your gate. Add a required contact name plus data vintage. If they share an EPD, capture the program operator and validity date.

Turn purchasing data into scope 3 gold

Export the year’s purchase orders and goods receipts, then harmonize units and currencies. Reconcile variances between BOM and actual receipts, since EPDs live on what was produced, not what was planned. Tag each line with a calculation method so audits are traceable and repeatable.

Don’t forget freight and packaging

Upstream transport belongs in Category 4, yet it rides on the same documents. Record ship from, ship to, weight, mode, and distance so you do not double count. Packaging can swing results for high volume, low density items, so get weights per unit while the box is still on the dock.

Quality checks that actually catch problems

Run simple reasonableness tests. Densities wildly outside known ranges point to unit errors. Year over year intensity that jumps without a process change is a red flag. If a supplier’s EPD factor is lower than physics allows, pause and request clarifications, dont just accept the number.

Make it a machine, not a project

Lock a data dictionary, RACI, and a quarterly refresh schedule. Keep a short change log that notes new suppliers, alternate materials, or process shifts. The goal is boring consistency that turns Category 1 from scramble to system.

From Category 1 to EPD ready

Once Category 1 is stable, LCA modeling moves faster and third party verification stays focused on evidence instead of archaeology. Teams win back time, sales wins bids that penalize missing declarations, and finance can see the impact of material switches before price talks start. That is how Scope 3 data becomes a commercial asset, not a chore.