Companies
How to Collect Scope 3 Supplier Emissions Data
Practical strategies for engaging suppliers, collecting primary emissions data, and progressively improving Scope 3 data quality.
Scope 3 Category 1 — purchased goods and services — is typically the largest emission source for companies, yet the hardest to measure. The challenge: you need data from hundreds of suppliers who have never calculated their own emissions.
The Data Quality Hierarchy
- Supplier-specific data: Actual emissions allocated to your goods — the gold standard
- Hybrid method: Combines supplier-specific with secondary data
- Average-data method: Industry-average factors per unit of goods
- Spend-based method: Factors per unit of currency — easiest but least accurate
Strategy: start at level 4 for everything, then upgrade your top emitters to levels 1–2.
Engaging Suppliers
- Keep it simple: Ask for specific data points, not full GHG inventories
- Remove friction: Use simple forms without requiring supplier accounts
- Explain why: Suppliers respond better when they understand regulatory context
- Set clear deadlines: With automatic reminders
Progressive Improvement
Year 1: 90% spend-based, 10% supplier-specific. That is fine. By year 3: primary data from top 20 suppliers. Track your data quality mix as a metric in its own right.