In This Guide
- A structured readiness assessment identifies gaps between your current GHG data management and verification requirements before the verifier arrives.
- The evidence pack should be organised by emission scope and source, with a clear audit trail from reported figures to source documents.
- Internal controls—including documented procedures, segregation of duties, and management review—significantly reduce verification findings.
- Common deficiencies include incomplete Scope 3 assessments, missing emission factor documentation, and gaps in the audit trail.
- A pre-verification dry run typically identifies 60-80% of issues the verifier would find, dramatically improving verification outcomes.
Readiness Assessment Framework
A readiness assessment evaluates your organisation's preparedness for GHG verification across five dimensions: boundary definition, data management, methodology documentation, internal controls, and evidence completeness. Conducting this assessment 8-12 weeks before the planned verification start date provides sufficient time to address any gaps identified.
Readiness Maturity Levels
| Level | Description | Verification Readiness |
|---|---|---|
| Level 1: Initial | GHG data is collected ad hoc, no documented processes, limited evidence | Not ready — 3-6 months of preparation needed |
| Level 2: Developing | Basic data collection in place, some documentation, gaps in audit trail | Partially ready — 6-10 weeks to address gaps |
| Level 3: Defined | Documented processes, systematic data collection, most evidence available | Mostly ready — 2-4 weeks of final preparation |
| Level 4: Managed | Robust processes, internal quality checks, comprehensive evidence pack | Ready — minor final checks only |
| Level 5: Optimised | Automated data collection, integrated systems, continuous improvement | Fully ready — verification is routine |
Self-Assessment Questions
Answer these questions to gauge your readiness:
- Can you produce a complete GHG inventory report with all mandatory content within 2 weeks of the reporting period end?
- Can you trace any reported emission figure back to its source activity data within 30 minutes?
- Are your data collection procedures documented and followed consistently across all sites?
- Has someone other than the preparer reviewed the inventory for errors and completeness?
- Can you provide emission factor sources and justification for every source in your inventory?
- Do you have a documented Scope 3 significance assessment with inclusion/exclusion rationale?
- Is your base year inventory documented with a clear recalculation policy?
Data Quality Requirements
Verifiers assess data quality across five dimensions as defined by ISO 14064-1 and the GHG Protocol. Understanding these requirements helps organisations collect and manage data to the standard expected during verification.
Activity Data Quality Hierarchy
Activity data sources vary in quality. In order of preference:
- Metered data: Direct readings from calibrated meters (gas, electricity, water). Highest quality — provides continuous, accurate primary data
- Invoice/billing data: Supplier invoices and utility bills. High quality — independently verified by the supplier
- Purchase records: Internal procurement records and delivery notes. Good quality if systematically managed
- Engineering estimates: Calculations based on equipment specifications and operating hours. Moderate quality — requires documented assumptions
- Proxy data: Estimates based on benchmarks, floor area, employee count, or revenue. Lowest quality — acceptable only for immaterial sources or where better data is genuinely unavailable
Data Quality Indicators
For each major data source, document these quality indicators:
- Source type: Metered, invoiced, estimated, or proxy
- Temporal coverage: Months or periods covered (flag any gaps)
- Geographic specificity: Site-level, regional, or corporate average
- Measurement uncertainty: Known accuracy of meters or estimates
- Assumptions: Any assumptions used in the calculation (documented)
Documentation Checklist by Scope
This checklist covers the documentation verifiers typically request, organised by emission scope. Use it to ensure completeness before submitting your evidence pack.
General Documentation (All Scopes)
- GHG inventory report with all mandatory content per ISO 14064-1
- Organisational boundary definition and consolidation approach documentation
- Operational boundary — scopes included and exclusion justifications
- Quantification methodology document describing the approach for each source
- Emission factor register with sources, versions, and applicability notes
- GWP values used and their source (IPCC AR version)
- Base year inventory and recalculation policy
- Uncertainty assessment (qualitative or quantitative)
- Internal review records and sign-off
- Prior year inventory and verification statement (if applicable)
- Change log documenting any methodology changes from prior year
Scope 1: Direct Emissions Evidence
- Stationary combustion: Fuel purchase invoices/delivery records, meter readings, boiler/furnace specifications, fuel type and calorific value documentation
- Mobile combustion: Fleet fuel cards/receipts, mileage logs, vehicle fleet register, fuel type records
- Process emissions: Production records, raw material consumption, process specifications, stoichiometric calculations
- Fugitive emissions: Refrigerant inventory, service/maintenance records (top-ups and disposals), leak detection records, equipment register with refrigerant types and charge quantities
Scope 2: Energy Indirect Emissions Evidence
- Location-based: Electricity invoices/bills for all sites, grid emission factor source documentation, steam/heat/cooling invoices
- Market-based: Renewable Energy Certificates (RECs) or Guarantees of Origin (GOs), power purchase agreement details, green tariff documentation, residual mix factors for uncovered consumption
- Reconciliation: Cross-reference between invoiced consumption and reported consumption, explanation of any differences
Scope 3: Other Indirect Emissions Evidence
- Purchased goods and services: Spend data by category, supplier-specific emission factors (if available), spend-based emission factor sources
- Business travel: Travel booking records, expense reports, distance calculations, travel agency reports
- Employee commuting: Commuting survey data, methodology for extrapolation, response rate
- Waste: Waste transfer notes, waste contractor reports, waste composition data, landfill vs recycling vs incineration breakdown
- Upstream transportation: Logistics data, tonne-km calculations, transport mode documentation
- Significance assessment: Documented assessment of all 15 Scope 3 categories with inclusion/exclusion rationale
Evidence Pack Structure
A well-organised evidence pack significantly reduces verification time and cost. Structure your evidence pack using a logical folder hierarchy that the verifier can navigate easily.
Recommended Folder Structure
- 01-GHG-Report/ — Final GHG inventory report, methodology document, uncertainty assessment
- 02-Boundaries/ — Organisational boundary map, entity list, consolidation approach documentation
- 03-Scope-1/
- 03a-Stationary-Combustion/ — Fuel invoices, meter readings, calculations
- 03b-Mobile-Combustion/ — Fleet data, fuel records, mileage logs
- 03c-Process-Emissions/ — Production data, process calculations
- 03d-Fugitive-Emissions/ — Refrigerant records, leak detection, service logs
- 04-Scope-2/ — Electricity bills, grid factors, RECs/GOs, market-based documentation
- 05-Scope-3/
- 05a-Significance-Assessment/ — Category screening document
- 05b-Category-[n]/ — Data and evidence for each included category
- 06-Emission-Factors/ — Emission factor register, source documentation, GWP references
- 07-Calculations/ — Master calculation workbook(s), or GHG software export
- 08-Base-Year/ — Base year inventory, recalculation policy, any recalculation records
- 09-Internal-Review/ — Review records, sign-off documentation, corrective actions taken
- 10-Prior-Year/ — Previous year's verification statement and management report
Internal Controls for GHG Data
Internal controls are the processes and checks that ensure GHG data is complete, accurate, and reliable. Strong internal controls reduce the risk of errors, improve verifier confidence, and often lead to fewer findings and lower verification costs.
Essential Controls
| Control | Purpose | Implementation |
|---|---|---|
| Documented data collection procedures | Ensure consistent data collection across sites and periods | Written SOPs for each data source with responsibilities, deadlines, and quality checks |
| Segregation of duties | Reduce risk of undetected errors or manipulation | Different people collect, compile, review, and approve the inventory |
| Automated data extraction | Reduce manual data entry errors | Direct feeds from utility accounts, fleet management systems, or ERP systems |
| Reconciliation checks | Identify discrepancies between data sources | Cross-check GHG data against financial records (fuel spend vs fuel volume) |
| Variance analysis | Detect anomalies requiring investigation | Compare current period to prior period and budget; investigate variances above a threshold |
| Management review and sign-off | Ensure senior accountability for data quality | Formal sign-off by a senior manager before submission to verifier |
| Version control | Prevent confusion over data versions | Clear naming conventions and version tracking for calculation workbooks |
Controls by Maturity Level
Minimum (first-time verification): Documented procedures, internal review by someone other than the preparer, and a clear audit trail from source to reported figures.
Standard (recurring verification): All minimum controls plus segregation of duties, reconciliation checks, variance analysis, and management sign-off.
Advanced (mature reporters): All standard controls plus automated data feeds, integrated GHG software, real-time monitoring dashboards, and continuous improvement based on verification findings.
Common Deficiencies
Based on our experience verifying hundreds of GHG inventories, these are the most frequently encountered deficiencies. Addressing these proactively before verification will significantly improve your outcome.
Top 10 Common Deficiencies
- Incomplete Scope 3 significance assessment: Missing or superficial assessment of indirect emission categories without documented rationale for exclusions
- Missing emission factor documentation: Emission factors used in calculations without documented sources, versions, or applicability justification
- Gaps in activity data: Missing months, sites, or emission sources within the declared scope without explanation
- Broken audit trail: Inability to trace reported figures back to source documents within a reasonable time
- Undocumented methodology changes: Changes to quantification methods, emission factors, or boundary from prior year without documentation or base year recalculation
- No internal review: The inventory was compiled and submitted to the verifier without any independent internal check
- Scope 2 dual reporting omission: Reporting only location-based or only market-based Scope 2, not both as required by ISO 14064-1:2018
- Inconsistent boundary application: Different consolidation approaches used for different entities without justification
- Refrigerant data gaps: Incomplete records for refrigerant equipment, top-ups, and disposals making fugitive emission calculation unreliable
- No base year recalculation policy: No documented policy defining when and how the base year inventory will be recalculated
Every deficiency identified during verification costs time and effort—both yours and the verifier's. Addressing the top 10 deficiencies listed above before the verification engagement starts typically reduces total verification time by 25-35% and significantly improves the likelihood of receiving an unqualified (clean) verification statement on the first attempt.
Pre-Verification Dry Run
A pre-verification dry run is an internal exercise that simulates the verification process before the external verifier begins work. It is one of the most effective ways to improve verification outcomes and is strongly recommended for first-time verifications and organisations seeking to improve from limited to reasonable assurance.
How to Conduct a Dry Run
- Assign an independent reviewer: Someone not involved in preparing the inventory—ideally with GHG or audit experience. External support can be engaged if internal capability is limited
- Review the GHG report: Check for completeness against ISO 14064-1 reporting requirements, consistency with prior year, and clarity of methodology documentation
- Test the data: Select a sample of emission sources and trace reported figures back to source activity data. Recalculate emissions for the sample and compare to reported values
- Check emission factors: Verify that emission factors are current, sourced from recognised databases, and appropriate for the activity data units
- Assess completeness: Verify that all sites and months within scope are included. Check for missing Scope 3 categories
- Review the audit trail: Attempt to navigate the evidence pack as a verifier would. Can you find supporting evidence for any selected data point within 15-30 minutes?
- Document findings: Record all issues identified and create a corrective action plan with deadlines
- Resolve findings: Address all identified issues before submitting the evidence pack to the verifier
Expected Outcomes
A well-conducted dry run typically identifies 60-80% of the issues an external verifier would find. Common dry run findings include calculation errors (transposition, formula errors), missing source documents, inconsistent data between workbooks, undocumented assumptions, and evidence pack organisation issues.
Audit Trail Requirements
The audit trail is the documented chain of evidence that allows anyone—internal reviewers, verifiers, or regulators—to trace a reported emission figure back to its original source data. A robust audit trail is non-negotiable for verification.
Audit Trail Components
- Source documents: Original invoices, meter readings, delivery notes, or system reports
- Data compilation: Spreadsheets or databases where source data is aggregated
- Calculations: Transparent calculations showing activity data x emission factor x GWP
- Aggregation: How site-level or source-level data rolls up to the total inventory
- Adjustments: Any manual adjustments with documented rationale
- Final report: The published GHG inventory report
Best Practices for Audit Trails
- Use cell references in spreadsheets rather than hardcoded values—this makes the calculation path visible
- Keep source data files linked or clearly referenced in calculation workbooks
- Use a consistent naming convention for files and tabs
- Maintain a data log recording when data was received, from whom, and any processing performed
- Avoid overwriting prior year data—maintain separate files for each reporting period
- If using GHG software, ensure the software supports data export and audit trail reporting
Timeline to Readiness
The path to verification readiness depends on your starting point. Here are recommended timelines for different maturity levels.
First-Time Verification: 3-6 Month Preparation
| Month | Activities | Deliverables |
|---|---|---|
| Month 1 | Define boundaries, select consolidation approach, establish data collection procedures | Boundary documentation, data collection SOPs |
| Month 2 | Collect Scope 1 and 2 data, select emission factors, begin calculations | Activity data compilation, emission factor register |
| Month 3 | Conduct Scope 3 significance assessment, collect priority Scope 3 data | Scope 3 significance assessment, initial Scope 3 data |
| Month 4 | Complete calculations, compile evidence pack, draft GHG report | Complete inventory, draft report, evidence pack |
| Month 5 | Conduct pre-verification dry run, resolve findings, finalise report | Dry run findings, corrected inventory, final report |
| Month 6 | Submit to verifier, support verification engagement | Verification statement |
Recurring Verification: 6-8 Week Preparation
For organisations with established processes from prior verifications:
- Weeks 1-2: Finalise reporting period data, update calculations, refresh emission factors
- Weeks 3-4: Complete inventory, compile evidence pack, update methodology documentation
- Weeks 5-6: Internal review and sign-off, address any issues identified
- Weeks 7-8: Submit to verifier, support verification engagement
The organisations that achieve the smoothest and most cost-effective verifications are those that treat GHG data management as a year-round activity rather than an annual scramble. Continuous data collection, quarterly internal checks, and proactive evidence management eliminate the last-minute pressure that leads to errors and gaps.
Frequently Asked Questions
What should be included in a GHG verification evidence pack?
A GHG verification evidence pack should include: the GHG inventory report with methodology documentation, organisational and operational boundary definitions, raw activity data by source (invoices, meter readings, fuel receipts), emission factor sources and references, calculation workbooks or software outputs, base year inventory and recalculation policy, uncertainty assessment, internal review records, and any prior verification statements. Organise by emission scope and source for easy navigation.
How far in advance should I start preparing for GHG verification?
Start preparation at least 6-8 weeks before the planned verification start date. For first-time verifications, allow 3-6 months to establish data collection processes, compile documentation, and conduct an internal review. The reporting period data should be finalised and internally reviewed before the verifier begins work.
What are the most common GHG verification deficiencies?
Common deficiencies include: incomplete Scope 3 significance assessments, missing documentation for emission factor selection, gaps in activity data (missing months or sites), lack of internal review before submission, undocumented methodology changes from prior years, inadequate audit trail, inconsistent boundary application across entities, and no base year recalculation policy.
What internal controls should be in place for GHG data?
Key internal controls include: documented data collection procedures with clear roles, segregation between data collection and review, automated data extraction where possible, reconciliation of GHG data to financial or operational records, management sign-off on the final inventory, version control for calculation workbooks, and a documented change log for methodology updates.
Should I do a pre-verification dry run?
Yes, a pre-verification dry run is highly recommended, especially for first-time verifications. Have someone independent of the inventory preparation process review the data using verification-style procedures: check calculations, trace data to source documents, assess completeness, and review methodology documentation. This typically identifies 60-80% of issues that the verifier would find.