Reported emissions have already been calculated and approved. Now someone else needs to review the work behind them. They may be an internal reviewer, a third-party assurance provider, or someone reviewing a regulatory filing.
Each reviewer is asking a different question. Internal QA/QC checks the team's work before the results are released. Third-party assurance independently tests a defined disclosure. Regulatory review checks a submission against the requirements of a particular program.
All three depend on something more basic: can the reviewer see how the reported emissions were determined? If the activity data, calculation method, assumptions, adjustments, and approvals are scattered across spreadsheets and email, the review becomes an exercise in reconstructing the work.
Terminology varies by program, so the applicable regulation or assurance engagement ultimately determines what each term means.
Measurement, reporting, and verification describes the broader process of measuring, reporting, and verifying emissions. This article asks a narrower question: what different kinds of review establish once emissions have been calculated or reported.
This is the operator's own review process. As part of that review, teams reconcile activity data to the reporting period, check that the calculation method was followed, review exceptions, and approve a specific version of the work.
Internal approval shows that the operator completed that review. A separate regulatory submission still has to meet that program's requirements.
If the activity data, the calculation method, and the approval cannot be followed from the reported total, the next reviewer has to reconstruct which inputs were actually accepted.
An independent party tests a disclosure the company has made, often a corporate inventory, against the criteria, boundary, and period named in the engagement.
The statement covers that engagement. Third-party assurance does not replace the operator's own QA/QC. A regulatory filing that uses a different boundary, different sources, or a different method is a different result. An assured corporate inventory can still be the wrong reported total for a facility report.
Who performs this check depends on the program. Some agencies review the report themselves. Others require an independent verifier under the rule. Use the regulation's word. EPA calls its own process verification.
Under the U.S. EPA Greenhouse Gas Reporting Program, submitted reports go through electronic validation and verification checks. EPA may follow up with reporters when those checks identify potential errors.
For petroleum and natural gas systems, Subpart W also requires the reporter to follow specified quality-assurance, missing-data, and record-keeping procedures. That work sits with the operator. EPA's verification applies to the GHGRP submission. It is not an independent assurance opinion on a separate voluntary disclosure.
Whoever reviews the submission still needs a path from the reported emissions back to the underlying calculation and supporting records.
A reported emissions value is the end of the calculation. A reviewer needs to be able to follow that result back to the activity data, calculation methods, assumptions, adjustments, and approvals behind it. The evidence does not have to live in one file.
A reviewer needs to see which activity data fed the reported value, and which reporting period those records cover. A combustion total depends on fuel use or runtime for specific equipment in specific months. If the annual result does not show which records were included, the reviewer cannot tell whether a late December volume was in the calculation or was added after the draft was approved.
They also need to know which calculation method and emission factors produced the version under review. Today's factor does not explain a value calculated on last year's factor. When an assumption changed the result, it should be visible on the version that used it.
Exceptions, substitutions, and adjustments are part of that history. Missing hours that were estimated, or an unusual value that required an adjustment, will change the reported emissions. If those decisions sit only in side files or email, the reviewer either accepts a result they cannot test or rebuilds them from old workbooks.
The approval record should make clear which version was accepted and what changed afterward. A signature on a PDF, or an email that says the total looks fine, may not show which version of the calculation was actually approved. If a production volume is corrected after approval, the revised value and the reason belong with that history. Otherwise the approved file and the submitted file are different claims, and the next reviewer has to work out which one went out the door.
Problems usually show up when a result moves from one use to another. A corporate inventory may have been independently assured, while a facility filing uses a different boundary, calculation method, or reporting period. EPA's verification applies to the GHGRP submission. It does not extend to a separate voluntary disclosure simply because some of the underlying activity data overlap.
The practical problem is less about the vocabulary than about the record. When the next review begins, the team needs to know which activity data, calculation method, assumptions, adjustments, and approvals produced the version being tested. If that trail has to be rebuilt from old workbooks and email, the review takes longer, and inconsistencies have another chance to surface.
The GHG Protocol Scope 3 Standard describes two levels of assurance: limited and reasonable. The level the reporting company requests determines how rigorous the assurance is and how much evidence is gathered. Reasonable assurance is the higher of the two. Absolute assurance is not provided, because not every input to the inventory can be tested. Evidence gathering is less rigorous under limited assurance than under reasonable assurance.
The same underlying activity data, such as fuel use, throughput, or runtime, may support both regulatory reporting and a voluntary disclosure. That overlap does not make the reported results interchangeable. The boundary, the calculation method, the emission factors, the sources included, and the reporting period can all differ. EPA's verification applies to the GHGRP data submitted under that program. It does not establish that a separate disclosure meets a different set of criteria.
Who can perform verification or assurance depends on the reporting program or the assurance engagement. Some programs specify qualifications or independence requirements for the reviewer. Others conduct the verification themselves. EPA conducts verification of GHGRP submissions. It does not require a third-party assurance opinion on that submission. For a voluntary inventory, check the reporting or assurance framework for its requirements on verifier qualifications and independence.
Review is easier when the evidence behind reported emissions is maintained while the calculation is being built, rather than assembled after someone asks for it. The reported value needs a clear path back to the activity data, calculation methods, exceptions, and approvals behind it.
Validere helps teams collect data, manage approvals, and preserve evidence, and it can work alongside the systems a company already uses. Learn more about emissions assurance and verification.