Assurance (or verification) is the process by which an independent third party reviews a company's greenhouse gas inventory and provides a formal opinion on whether the reported emissions are accurate, complete, and prepared in line with a recognised standard such as the GHG Protocol or ISO 14064-1.
Assurance comes in two levels. Limited assurance provides a moderate level of confidence ("nothing has come to our attention to suggest…"). Reasonable assurance provides a higher level of confidence and is closer to a financial audit in rigour and cost.
Why it matters
Some disclosure regimes — including parts of the EU Corporate Sustainability Reporting Directive (CSRD) — now require assured emissions data. Procurement bodies, investors, and rating agencies increasingly distinguish between assured and unassured figures.
Even where assurance is not formally required, building a footprint to an assurance-ready standard signals rigour and reduces the cost of obtaining assurance later. An assurance-ready report has documented methodology, traceable data sources, justified assumptions, and a clear audit trail from raw data to headline number.
A practical example
A listed company commissions an independent verifier to provide limited assurance over its Scope 1, 2, and material Scope 3 figures. The verifier samples utility bills, fuel records, and waste tickets, checks the application of emission factors, reviews the consolidation approach, and issues a formal opinion alongside the company's annual sustainability report.
We deliver every report to an assurance-ready standard. See what that means in practice on the methodology page.