The 15 categories of Scope 3
The GHG Protocol divides Scope 3 emissions into 15 distinct categories. Upstream categories (1-8) include purchased goods and services, capital goods, fuel- and energy-related activities not in Scope 1 or 2, upstream transportation and distribution, waste generated in operations, business travel, employee commuting, and upstream leased assets. Downstream categories (9-15) include downstream transportation and distribution, processing of sold products, use of sold products, end-of-life treatment of sold products, downstream leased assets, franchises, and investments.
Not every category is material for every organisation. A retail business sees most emissions in purchased goods and services and downstream transportation. A financial services business sees most emissions in investments. A SaaS company sees most emissions in cloud infrastructure (purchased goods and services) and employee commuting. Organisations are expected to perform a materiality assessment, then prioritise measurement effort on the categories that contribute meaningfully.
Why Scope 3 is the hardest to measure
Unlike Scope 1 and 2, Scope 3 emissions are not directly under the reporting organisation's control. The data lives in suppliers' systems, customers' systems, and the broader economy. Three measurement approaches exist: spend-based (multiply procurement spend by industry-average emissions factors – fast but imprecise); activity-based (multiply physical activity quantities by emissions factors – more precise, requires more data); supplier-specific (use actual emissions data from each supplier – most precise, requires supplier engagement).
Most organisations begin with spend-based estimation across all 15 categories, then progressively shift to activity-based and supplier-specific data for the highest-emitting categories. The shift to supplier-specific data is what makes Scope 3 supplier readiness matter: a supplier that publishes verified emissions data with assurance is dramatically more useful to its customers' Scope 3 reporting than one that does not.
Scope 3 supplier readiness: a 14-check methodology
ESG Orgs. publishes a 14-check methodology for assessing whether a supplier is positioned to meet its customers' Scope 3 reporting needs. The checks cover four categories: structured data (sectors, services, SDG alignment present in machine-readable form); emissions transparency (Scope 1/2/3 reported, third-party assured, SBTi-aligned, climate targets set); verification depth (platform-verified, holding certifications, holding industry accreditations); and profile quality (description, address, website populated).
Each check is binary (passed / not passed) and contributes to a 0-100 score. Suppliers scoring above 70 are categorised 'Ready'; 40-70 'Partial'; below 40 'Not Ready'. The full methodology and per-organisation results are public, and the dataset is downloadable at /data under CC BY 4.0.
Finding Scope 3-ready suppliers
Procurement teams looking to engage Scope 3-ready suppliers can search the directory and filter by readiness level, sector, and region. The supplier readiness API allows automated lookup against the verified corpus, supporting integration with procurement workflows. The open dataset at /data publishes the full readiness score corpus as JSON and CSV under CC BY 4.0, with stable URLs for citation in research and procurement specifications.