How should emissions factors activity data and calculation methods be defined an

Define a canonical schema for each entry that explicitly separates activity data (quantities, units, time period), emission factors (source, version, geographic/temporal/tech representativeness), and calculation method (formula, hierarchy, assumptions). Reference emission factors with immutable IDs and versioning to prevent silent changes; include factor metadata (e.g., scope category, gas coverage, GWPs used) and link to source documentation. Adopt calculation hierarchies that prefer supplier- or site-specific activity data and factors before moving to hybrid or spend-based methods, and record why a lower-tier method was used. Establish a common unit library and enforce unit conversions at ingestion to eliminate ambiguity. Store the global warming potential (GWP) assessment basis (e.g., IPCC AR6 100-year) alongside results and enable recalculation under alternate GWPs. Attach data quality ratings (reliability, completeness, temporal/geographic/technological match) to both activity data and factors. Finally, keep a clear lineage: source system, collection method, reviewer, and approval timestamps to ensure auditability and reproducibility. This alignment with GHG Protocol guidance and IPCC factor quality principles yields consistent, defensible results across reporting cycles. Key Takeaway: Separate data, factors, and methods with versioned references and quality metadata to ensure consistent, auditable carbon calculations.