Start with a practical test: could a colleague reconstruct a material number without relying on the person who prepared it?
A defensible inventory does not mean every input is exact. It means the organization can explain what it included, how it calculated the result, where estimates enter, and how the work was reviewed.
Make five things visible
- Boundary. State the entities, activities, reporting period, and emissions sources included. Explain exclusions.
- Source. Keep an index of bills, fuel records, supplier information, and other inputs. Identify the reporting period and source owner.
- Method. Record calculation logic, units, emission factors, and the reasons for material estimates.
- Review. Show who checked completeness, unusual movements, changes in method, and calculation accuracy.
- Limitations. Describe gaps and uncertainty, and assign an owner to improvements that matter.
Separate preparation from assurance
Preparing an inventory and its evidence supports an external review. It does not itself provide an independent assurance opinion. Agree the intended reporting use and any external assurance requirements early.
Start with one material reporting number
Trace it from the reported total back to the source. Note every point where an assumption, undocumented adjustment, missing approval, or unavailable record interrupts the trail. Use those observations to prioritize the next process improvements.