Example Policy for Recalculating Or Resetting Base Year
Introduction
ISO 14064-1 requires organisations to establish a clear and consistent approach to recalculating or resetting their GHG emissions base year to maintain accurate and comparable emissions data over time. A defined base year recalculation and resetting policy supports credible tracking and reporting of emissions performance across all organisational units and activities included in the GHG inventory.
The template below provides an example policy that organisations can adapt to manage base year recalculation, base year resets, and, where appropriate, continued comparison at the emission source level.
1. Purpose
This policy defines how <Business name> manages recalculation or resetting of its GHG emissions base year to maintain data integrity and comparability over time.
Where recalculation or resetting is not required or feasible, this policy also defines how <Business name> will continue to assess emissions performance by comparing emissions at the individual emission source level.
Recalculation is undertaken to preserve comparability of emissions data, not to restate or improve reported performance.
2. Scope
This policy applies to:
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All organisational units and operations within the defined inventory boundary
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All scopes included in <Business name>’s GHG inventory
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All base year comparisons and emissions reduction claims
3. Triggers for Base Year Recalculation
<Business name> will consider recalculating the base year where changes materially affect base year emissions and recalculation is required to maintain meaningful comparability over time.
Potential triggers include:
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Structural changes (e.g. mergers, acquisitions, divestitures, outsourcing or insourcing) where these changes materially affect base year emissions and recalculation is necessary for like-for-like comparison
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Changes to organisational or operational boundaries
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Improvements in data quality or availability that materially alter previously reported emissions
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Changes to calculation methodologies or emission factors with a material impact
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Identification of significant errors in previous inventories
Structural changes such as acquisitions or divestments do not automatically trigger recalculation.
Acquisitions or divestments of activities that were not operational in the base year will be treated as new emission sources and will not trigger recalculation.
Organic growth or decline (e.g. changes in production volume, occupancy, or activity levels within existing operations) does not, on its own, trigger base year recalculation.
4. Significance Threshold
A base year recalculation or reset is required where the cumulative impact of changes is 5% or greater of total base year emissions.
Changes below this threshold will be documented and tracked but will not trigger recalculation.
5. Recalculation vs Reset Decision
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Recalculation will be undertaken where historical data is available and can be reasonably adjusted to maintain consistency and comparability, without reliance on assumptions that would materially reduce data integrity.
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Resetting the base year will occur only where recalculation is not feasible due to data gaps, methodological constraints, or where recalculation would require extensive data reconstruction, estimation, or assumptions that are not reasonable relative to the decision-making value of the result.
Where the base year is reset, prior emissions reduction claims are no longer valid for external reporting or marketing purposes.
6. Procedure
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Identify and document the change or inconsistency.
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Quantify the impact on total emissions.
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Assess materiality against the significance threshold.
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Determine whether recalculation is feasible and appropriate.
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Recalculate the base year or, where not feasible, reset the base year and document the rationale.
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Where recalculation is required, prioritise use of actual historical data; where unavailable, use representative data or reasonable estimates and clearly disclose assumptions.
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Update emissions trends, targets, and claims as required.
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Conduct internal review and submit for third-party verification where applicable.
7. Source-Level Comparisons
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In some circumstances, <Business name> may choose not to recalculate the base year, particularly where changes primarily affect Scope 3 emissions data (e.g. updated supplier data, revised category coverage, or improved estimation methods) and full recalculation is not feasible or would be excessively time-consuming.
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In these situations, emissions performance will continue to be assessed by comparing unchanged and comparable emission sources only, rather than total inventory emissions.
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<Business name> will continue to compare at the emission source level until:
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New significant emissions sources are added (e.g. new product lines, services, facilities, or Scope 3 categories) and sufficient data is available to establish a standard and consistent calculation approach, or
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Significant inconsistencies in emissions data cannot be resolved through recalculation within the defined significance threshold.
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Once the base year is reset, <Business name> will no longer claim prior emissions reductions in external reporting or marketing communications.
8. Reporting and Disclosure
All base year recalculations or resets will be transparently disclosed in GHG emissions reports, including:
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The reason for the recalculation or reset
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The methods applied
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The impact on historical emissions, trends, and claims
9. Review
This policy will be reviewed at least annually, or following significant organisational or methodological changes, to ensure continued alignment with ISO 14064-1 and recognised good practice.