ESG Data Collection, Measurement, and Assurance
Domain 3 tests the plumbing behind reported numbers: how boundaries are drawn, how metrics are measured or estimated, what controls exist, and what an assurance statement actually covers. Questions usually hinge on boundary consistency, data quality disclosure, and the distinction between limited and reasonable assurance.
Boundary and source data
The organisational boundary may follow operational control, financial control or equity share, and the choice must be stated and applied consistently across metrics. Data should come from source systems (utility invoices, meter reads, ERP, HRIS, supplier questionnaires) rather than the prior year's report. Consolidation rules, entity lists and factor versions belong in the methodology note.
Data quality hierarchy
Measured data (direct metering, invoices) ranks above calculated data (activity multiplied by a factor) which ranks above estimated or modelled data. Disclose the mix per metric, the method used, and the emission or conversion factor version, for example a named national conversion factor set or life-cycle database release.
Internal control
Segregation of duties, documented methodology, variance review thresholds, a single source of truth, an evidence pack per reported data point, and sign-off at entity and group level. Many preparers now map controls to the COSO framework extended to sustainability reporting.
Assurance
Limited assurance gives a negative conclusion (nothing has come to our attention); reasonable assurance gives an audit-level opinion and costs far more. Common standards: ISAE 3000 (Revised) for general ESG information, ISAE 3410 for GHG statements, and AA1000AS with Type 1 (principles) and Type 2 (principles plus specified performance information). The assurance scope, level, criteria and provider independence must be stated explicitly.
Worked example
A site buys renewable electricity certificates. Under the GHG Protocol Scope 2 Guidance, report location-based emissions using the grid average and market-based emissions using contractual instruments. The certificates reduce the market-based figure only; they are not subtracted from location-based. Reasoning: the two figures answer different questions and both are required.
Traps that cost marks
- Mixing units (kWh and MWh, kilograms and tonnes) or GWP versions between years.
- Double counting across Scope 3 categories or between a buyer and its supplier.
- Describing a report as assured when only one KPI was in scope.
- Leaving the base year unrecalculated after acquisitions, divestments or methodology changes.