Every GHG verification is performed at an agreed level of assurance, set in the agreement before planning starts (ISO 14064-3:2019). The two levels are not a quality grade; they are two different engagements.
Limited assurance
The verifier performs fewer and less extensive procedures and gives a conclusion in negative form — that nothing has come to its attention to indicate that the statement is materially misstated.
Reasonable assurance
The verifier gathers sufficient appropriate evidence to give a conclusion in positive form — that the statement is fairly presented in all material respects. It requires more testing, more sampling and more verification time.
Who sets it
Usually the intended user: a GHG programme, a regulator, a lender or a buyer specifies the level in its rules. Where nobody does, the choice is the organization’s, and it should reflect how the statement will be used.
What changes with it
The materiality threshold, the evidence-gathering plan, the sample sizes and the wording of the statement. Changing the level after planning means re-planning the engagement.
