If your facility is required to report and verify its greenhouse gas (GHG) emissions in Ontario, being prepared can make the verification process much easier to navigate. Missing documentation, data gaps, or questions about calculations can create challenges when verification is already underway.
Knowing what to expect and preparing early can help you identify and address these issues before they become bigger problems.
This guide explains how to prepare for GHG verification in Ontario, including what to expect, key reporting requirements, and practical steps you can take to get your facility ready.
Why GHG Verification Matters
Greenhouse gas reporting forms the foundation of many climate-related programs and corporate sustainability initiatives. Whether emissions data is being used for regulatory reporting, emissions trading programs, environmental, social and governance (ESG) disclosures, or corporate target setting, stakeholders need confidence that the information is accurate and reliable.
Verification helps organizations:
- Demonstrate compliance with Ontario regulatory requirements
- Improve the quality and reliability of emissions inventories
- Identify data gaps and process improvement opportunities
- Increase confidence among regulators, investors, customers, and other stakeholders
- Support broader corporate decarbonization and sustainability goals
Verification is not intended to “find mistakes.” Rather, it is a structured assessment designed to provide assurance that reported emissions are complete, accurate, and prepared in accordance with applicable regulatory requirements and recognized standards.
Ontario’s Regulatory Framework
Ontario’s GHG reporting and verification requirements are primarily established under Ontario Regulation 390/18 (Greenhouse Gas Emissions: Quantification, Reporting and Verification) and the Emissions Performance Standards (EPS) program. O. Reg. 390/18 sets out requirements for quantifying, reporting and, for covered facilities, verifying GHG emissions.
Facilities may be required to report their GHG emissions if they:
- Emit 10,000 tonnes or more of CO₂e per year
- Import electricity into Ontario and meet the applicable regulatory requirements
- Are registered, or required to register, under the EPS program
Reports are to be submitted by June 1 annually Facilities registered or required to register under the EPS program are considered covered facilities and must have their emissions report independently verified by an accredited verification body by September 1 annually.
Verification provides an independent assessment of the facility’s emissions report and whether it has been prepared in accordance with regulatory requirements. The process can involve reviewing emissions data, supporting documentation, data management systems and facility operations, as well as site visits where required.
What Verifiers Are Looking For
Many organizations view verification as a review of their final emissions numbers. In practice, verifiers spend just as much time examining the data, methodologies, assumptions, and records that support those numbers.
Verification is designed to provide confidence that reported GHG information is accurate, complete, and supported by objective evidence. Understanding the areas that are typically examined during a verification can help organizations focus their preparation efforts, improve data quality, and identify potential issues before the verification process begins.
Key areas of review can include:
Data completeness
Have all applicable emission sources been identified and accounted for in the inventory? Missing information can lead to questions during verification and may affect the accuracy of the reported emissions.
Data quality and traceability
Can the data in your report be traced back to supporting records? Having fuel records, utility invoices, production data, monitoring records, laboratory analyses, and other relevant documentation readily available can make the review easier to navigate.
Calculation methodologies
Are the appropriate methodologies being used, and are your calculations clearly supported? Assumptions, emission factors, and calculation approaches should be documented so the verifier can understand how reported emissions were determined.
Internal controls
How does emissions data move from its original source into the final report? Clear processes for collecting, reviewing, and approving data can help reduce errors and make supporting information easier to retrieve.
Changes from previous years
Significant changes in emissions, production, fuel use, facility operations, or calculation methodologies may require additional explanation. Keeping records of what changed and why can help your team respond to questions during verification.
How to Prepare for GHG Verification
For facilities preparing for verification, the key is to start early and make sure the data, documentation and processes supporting the emissions report are organized and ready for review. That preparation can make the verification process more efficient and help identify issues before they become compliance challenges.
Here are eight steps facilities can take to prepare for GHG verification:
-
Start collecting data early
Avoid waiting until the reporting deadline approaches to assemble your emissions data. Collecting and reviewing data throughout the reporting year gives your team more time to identify missing information, investigate unusual results, and address potential data quality issues.
-
Keep supporting documentation organized
Verification involves more than reviewing the final emissions numbers. Your verifier will need to review the records and documentation supporting the data and calculations included in your report.
Keeping this information organized and accessible can make it easier to demonstrate where data came from and how reported values were determined.
-
Document your assumptions and calculation methods
Clearly document the methodologies, assumptions, and data sources used to calculate your facility’s emissions. This is particularly important where calculations rely on estimates or facility-specific information.
A clear record of your approach helps the verifier understand how reported emissions were calculated and can help your own team maintain consistency from one reporting year to the next.
-
Review changes at your facility
Consider what changed during the reporting year and whether those changes could affect your emissions report.
Changes to equipment, fuels, production, processes, or other facility operations may affect the information included in your GHG inventory. Reviewing these changes ahead of verification can help support accurate reporting and provides a clearer picture of facility operations during the reporting year.
-
Conduct an internal quality review
Before verification begins, conduct an internal review of your emissions data, calculations, and supporting records.
Look for missing data, inconsistencies, calculation errors, or significant changes that may require further investigation. Identifying these issues internally gives your team an opportunity to address them before they arise during verification.
-
Address known issues before verification begins
If you already know there are gaps, unusual data points, or areas of uncertainty, investigate them early rather than waiting for the verifier to identify them.
Documenting the issue, how it was addressed, and any assumptions that were made can help your team respond efficiently to questions during verification.
-
Engage your verifier early
Engaging your verification team early can help clarify expectations and identify the documentation that will be needed during the verification process.
Early communication also gives your team more time to organize records and prepare for the review. While the verifier must remain independent, understanding the verification process and what information will be required can help your facility prepare more effectively.
-
Know your reporting deadline
Build Ontario’s reporting deadline into your preparation schedule so there is sufficient time for internal review and verification before your report is submitted.
For facilities subject to Ontario’s annual reporting requirements, emissions reports must be submitted by June 1 following the reporting year. Where third-party verification is required, the associated verification report must be submitted by September 1.
For example, the report for the 2025 reporting year, the emissions report was due June 1, 2026, and the verification report was due on September 1, 2026.
The Value Beyond Compliance
One of the most overlooked benefits of GHG verification is the operational insight it can provide. During the verification process, organizations often discover opportunities to improve data management systems, enhance monitoring practices, and strengthen internal reporting procedures.
These improvements can support:
- Future compliance activities
- ESG reporting initiatives
- Decarbonization planning
- Energy management programs
- Corporate sustainability commitments
High-quality emissions data enables better decision-making. As climate-related reporting expectations continue to increase, organizations that invest in strong GHG data management practices today will be better positioned for tomorrow’s regulatory and business requirements.
