How do I combine average-data and spend-based factors in one Category 1 total, as the Greenhouse Gas Protocol's electronics example does?
Group what you buy. Items with known mass use mass times a process-based factor per kilogram; items with only spend use the amount spent times an environmentally extended input-output (EEIO) factor. The Greenhouse Gas (GHG) Protocol's electronics example adds both to 54,100 kilograms of carbon dioxide equivalent (CO2e).
Why the guide groups purchases
Company E buys over 1,000 components and raw materials for electronic goods. Instead of getting data from every supplier and allocating emissions across 1,000 goods, it groups what it buys: semi-processed components, and raw materials.
Mass is available only for the components. The guide says the company works that out by combining primary data from its systems with extrapolation. For raw materials only spend is available, taken from its enterprise resource planning system.
Which factor goes with which group
The guide says the spend-based method is for when the supplier-specific, hybrid and average-data methods are not feasible, and that companies may combine the material-based and spend-based methods using process-based and EEIO data for different goods. Spend should be in market values, with inflation data where the factor year differs from the spend year.
- Components, where mass is known: process-based cradle-to-gate factors per kilogram, from life cycle databases or industry associations.
- Raw materials, where only spend is known: EEIO cradle-to-gate factors per unit of money.
What the split shows
In the example six component lines produce about 78 percent of the total, and nine raw-material lines about 22 percent. Spend-based lines are easy to build but they move with price, so they are the first to replace when a supplier starts sending real figures (our reading).
The guide's electronics example
- Hard drive 400 x 20 = 8,000; integrated circuits 200 x 10 = 2,000; liquid crystal display 500 x 40 = 20,000
- Semiconductors 100 x 70 = 7,000; battery 1,500 x 3 = 4,500; keyboard 300 x 3 = 900
- Components (mass in kilograms): 8,000 + 2,000 + 20,000 + 7,000 + 4,500 + 900 = 42,400 kilograms CO2e
- Raw materials (spend in dollars x factor per dollar): 1,500 + 900 + 1,200 + 3,000 + 300 + 1,000 + 1,500 + 300 + 2,000 = 11,700 kilograms CO2e
- Total: 42,400 + 11,700 = 54,100 kilograms CO2e
The guide says the activity data and factors are examples and do not refer to actual data. The spend lines are in dollars with a factor per dollar; for rupee spend see the linked page on tax, inflation and currency.
What Senseible does here
Senseible reads purchase invoices into dated records with quantity, unit and factor on each line, and marks lines without a usable quantity as needing data. It does not choose your factors for you.
- What a spend-based factor includes
- Tax, inflation and currency in spend-based Scope 3
- Category 1 method order
- Scope 3 supplier evidence
Last reviewed 2026-11-05. Totals were multiplied out from the guide's own tables and match its printed 54,100.