All 15 Scope 3 Categories — Where Should an Organization Start

Scope 3 covers the indirect emissions across your value chain — purchased goods, transport, employee commuting, all the way to end-of-life treatment of sold products. The GHG Protocol splits it into 15 categories, and it is usually the largest share of a corporate footprint.

Do not attempt all 15 in year one

The standards recommend materiality: assess which categories are significant to your business first. Manufacturers are usually heavy in category 1 (purchased goods and services) and categories 4/9 (upstream and downstream transport). Service businesses lean toward category 6 (business travel) and category 7 (employee commuting).

A sequence that works in practice

1. Year one: get Scope 1–2 solid and run a Scope 3 materiality assessment
2. Year two: start with 3–4 large categories where data already exists — commuting (HR data), transport (procurement data)
3. Following years: expand into categories that require supplier data

In GCarbon

The system covers all 15 Scope 3 categories with purpose-built models — employee commuting by travel mode, per-capita paper use — and a dashboard showing each category's share, so you prioritize with real numbers.

A fast materiality screen

Start with spend-based screening — multiply spend per category by industry-average emission factors to estimate which categories are likely large. Accuracy is low but speed is high, which is all prioritization needs. Then go activity-based only for the categories that rank — standards accept mixing both methods as long as you disclose which category uses which.

Getting supplier data that actually arrives

For supplier-dependent categories (like purchased goods), start with the top 10-20 suppliers covering most of your spend. Send a template that is easy to complete and asks only what is needed — suppliers with their own CFO can provide allocations directly, while for the rest, asking their energy types and production volumes already beats industry averages.