How to calculate Scope 3: a practical guide
Scope 3 (indirect value-chain emissions) is often the largest and most complex. Here is how to tackle it step by step.
Identify the relevant categories
The GHG Protocol defines 15 categories (purchases, transport, travel, product use, end of life, etc.). Not all apply: start by identifying the most significant for your activity (relevance analysis).
Collect and calculate
For each category: activity data (quantities, spend) x emission factor. You often start with a monetary approach, then refine with physical and primary data (suppliers). UltraCarbon guides this collection by theme.
Frequently asked questions
Must all 15 categories be calculated?
No, only those that are relevant and significant. Document those excluded and why.
Where to start with Scope 3?
With purchased goods and services, often the top item, then transport and the use of products sold.