Audit Trail
A complete documented record of every data input, emission factor applied, calculation performed, and assumption made in a GHG inventory — enabling independent verification of the final emission figures.
An audit trail in carbon accounting is the complete, traceable record that allows an independent verifier to reconstruct and confirm every emission figure in a GHG inventory. It is the direct equivalent of the supporting documentation required in financial auditing — purchase invoices, meter readings, calculation formulas, emission factor citations, and any adjustments made.
What an audit trail must contain
For every emission source in a BRSR-compliant GHG inventory:
- Activity data source: Where did the fuel consumption or electricity figures come from? (Invoice reference, meter ID, production record)
- Emission factor: Which factor was used? (IPCC source, table reference, version, value)
- GWP values: Which IPCC Assessment Report? Which time horizon?
- Calculation formula: How was tCO2e derived from activity data and emission factors?
- Data quality: Were any estimates used? What uncertainty applies?
- Any corrections: Was any prior period data restated? Why?
BRSR Core assurance requirement
For companies subject to BRSR Core assurance, the audit trail is what assurance firms examine. An inventory without a traceable audit trail cannot receive a clean assurance opinion — regardless of how accurate the final numbers appear.
Spreadsheets vs purpose-built software
A well-maintained spreadsheet can theoretically constitute an audit trail, but version control, formula integrity, and traceability are difficult to demonstrate in Excel. Purpose-built carbon accounting software with a calculation log function provides a more defensible audit trail for assurance purposes.