How to Select and Document Emission Factors

An emission factor is a governed input, not a lookup value

The same activity can produce very different results depending on which factor is applied. Suitability depends on activity match, geography, year, technology, boundary, unit compatibility, and source quality — not just availability.

What to check before applying a factor

• Does it represent the right activity, fuel, or material?
• Does it match the country, grid, or region where the activity occurred?
• Is it current for the relevant reporting period?
• Are the included gases and GWP basis appropriate for your inventory?
• Does its boundary (e.g. combustion-only vs. lifecycle) match your intended use?

What to record for every factor you apply

• Factor name, publisher, and dataset version
• Publication year and applicable geography
• Unit and calculation boundary
• Date the factor was applied, and by whom

Why versioning matters

Factor libraries update as grids, technologies, and guidance change. Recording which version was used for each historical calculation is what lets you explain — rather than silently absorb — a year-over-year change that had nothing to do with your actual operations.

See OCEANS™ Sustainability’s Emission Factors methodology for the full governance model this guide summarizes.