Warning signs include: rapid growth in data sources (meters, suppliers, logistics feeds), recurring restatements, inability to reproduce results, upcoming assurance requirements, multi-entity consolidations, and regulatory filings demanding digital tagging. If cycle times exceed financial close or manual reconciliations dominate, move to a governed ledger.
Stage the transition: (1) Readiness assessment—map existing inventory processes, control gaps, and data owners. (2) Define master data and taxonomy—organizational boundaries, emission sources, activity types, factors, and calculation methods. (3) Build integrations—automate ingestion from ERPs, utilities, and procurement; version emission factors. (4) Pilot critical scopes/entities with parallel runs against your current spreadsheet model to validate outputs. (5) Implement controls—segregation of duties, approval workflows, and audit trails. (6) Operationalize reporting—produce location- and market-based Scope 2, category-level Scope 3, and assurance-ready data lineage.
Maintain a change log and a formal methodology document; conduct periodic management reviews and third-party limited assurance to harden processes before broad rollout.
Key Takeaway: Move when complexity, assurance, or regulatory demands outgrow spreadsheets; execute a controlled, parallel-run migration with strong data governance and integrations.