October 5, 2026 · Scope 3 · 4 min read
For most companies, the bulk of emissions arises in the supply chain rather than at their own sites. The quality of a Scope 3 inventory therefore depends on the quality of supplier data. This post describes a practical way to collect that data and how to build a reduction target on top of the inventory.
The GHG Protocol defines several methods for Scope 3 Category 1 (purchased goods and services). The spend-based method multiplies purchase value by an industry-average factor; it is fast, but your result does not change even when your supplier becomes more efficient. The supplier-specific method relies on the supplier's actual energy and fuel use, which is what makes reductions visible.
Asking a small supplier for a full carbon inventory is unrealistic. Three items that can be read from invoices are usually a sufficient start: annual electricity use (kWh), natural gas use (m³) and diesel use (litres). You also need the share of the supplier's output or revenue that goes to you.
Suppose a supplier uses 120,000 kWh of electricity, 8,500 m³ of natural gas and 1,000 litres of diesel per year. With the factors the platform uses (electricity 0.469 kg CO2e/kWh, natural gas 2.067 kg CO2e/m³, diesel 2.662 kg CO2e/litre), total emissions are:
If 12.5% of the supplier's revenue comes from you, the share allocated to you is 76,512 × 0.125 = 9,564 kg CO2e. This figure covers the supplier's Scope 1 and 2 emissions; it does not cover upstream emissions from the supplier's own raw materials. State that boundary in your report.
Once the inventory exists, pick a base year and a target year. A company with 100,000 kg CO2e in base year 2024 that targets a 42% reduction by 2030 has a target-year level of 58,000 kg CO2e. On a linear pathway that means cutting 7% of base-year emissions, or 7,000 kg CO2e, every year; the allowed level for 2026 is 86,000 kg CO2e.
The Science Based Targets initiative's (SBTi) 1.5°C-aligned absolute contraction approach implies a linear reduction of at least 4.2% per year. That rate is a useful benchmark for your own target; official SBTi approval is a separate application and validation process.
The Supplier Data Portal generates a link for your company; suppliers enter their consumption and the share going to you without creating an account, and the total is transferred to your inventory as Scope 3 Category 1. The Reduction Target card on the dashboard shows each year's budget next to actual emissions, based on your base year and target year.
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The Supplier Data Portal is available on Pro and Enterprise plans; the reduction target card is available on all plans.
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