How does a simple PCF calculation look?

Illustrative example: gate-to-gate share for a forging unit

Take the forging unit from our GHG inventory guide. Its Scope 1 and 2 in one year were about 364.4 tCO2e (illustrative, using IPCC 2006 diesel defaults and the CEA CO2 Baseline Database, Version 22.0 grid factor of 0.675 tCO2/MWh for FY 2025-26). It made 2,000 tonnes of forgings.

• Manufacturing (gate-to-gate), allocated by mass: 364.4 tCO2e / 2,000 t = about 0.18 tCO2e per tonne of forgings.
• Raw material (cradle-to-gate): add the footprint of the steel bought per tonne of output, including scrap losses. Ideally this comes from the steel supplier's own verified footprint; otherwise from a stated LCA database value.
• Inbound transport: add the freight emissions for bringing steel to the plant.

The sum is the cradle-to-gate PCF per tonne. In most metal products the raw material stage is large, which is why buyers push for supplier-specific steel and aluminium data. Mass allocation is only one option; if the unit makes very different products, a physical or economic basis may be fairer, and the choice must be disclosed.