UK SRS S2 Scope 1, Scope 2 and Scope 3 Emissions: Complete Measurement Guide

The three scopes have different sources and boundaries but share one controlled measurement architecture.

At a glance

1. Start with the disclosure architecture, not the emissions spreadsheet

The measurement project begins with a reporting architecture. UK SRS S2 paragraph 29(a) asks for absolute gross emissions classified as Scope 1, Scope 2 and Scope 3. “Gross” means the emissions are reported before deductions for carbon credits, avoided emissions, removals or renewable-energy claims. Credits and removals may be relevant elsewhere, but they do not reduce the gross inventory disclosed under paragraph 29(a).

The same paragraph also requires an explanation of the measurement approach, inputs and assumptions, why they were chosen, and changes made during the period. The disclosure is therefore both a number and an account of how the number was produced.

2. Reconcile the reporting entity, accounting group and other investees

UK SRS S1 establishes the reporting entity for sustainability-related financial disclosures by reference to the related financial statements. UK SRS S2 then adds a specific presentation requirement for Scope 1 and Scope 2: emissions are disaggregated between the consolidated accounting group and other investees, such as associates, joint ventures and unconsolidated subsidiaries. This is a presentation bridge—not permission to ignore investees or to use an undocumented boundary.

3. Measure Scope 1: direct sources within the selected boundary

Scope 1 normally covers direct emissions from sources owned or controlled under the selected GHG accounting approach. The source register should distinguish stationary combustion, mobile combustion, process emissions and fugitive emissions. Refrigerants deserve separate attention because additions, recoveries, equipment movements and gas-specific GWP values can make a small activity record financially and quantitatively significant.

Reconcile fuel invoices and tank movements to operational consumption, fleet records and general-ledger accounts.

Maintain equipment and refrigerant registers with gas type, opening balance, purchases, recoveries, closing balance and service evidence.

Document process-emissions formulas, production data, stoichiometric factors and engineering approvals.

Test units, heating-value basis, duplicate records, cut-off and source completeness.

4. Measure Scope 2: the location-based amount is the required core

Scope 2 covers emissions from purchased or acquired electricity, steam, heat and cooling. UK SRS S2 specifically requires a location-based Scope 2 figure. This generally uses grid-average or other location-representative emission factors for the place where energy is consumed. Contractual instruments can add useful information, but they do not replace the required location-based amount.

A Scope 2 control file should reconcile consumption by site and meter, identify the applicable grid factor, record any supplier-specific factor, and link PPAs, certificates or energy attributes to the relevant market, vintage, volume, ownership and retirement evidence.

5. Assess all 15 Scope 3 categories

The Scope 3 boundary is the upstream and downstream value chain, not a simple extension of the consolidation perimeter. UK SRS S2 requires the entity to disclose the categories included in its Scope 3 measure by reference to the 15 categories in the GHG Protocol Scope 3 Standard. A category screening should consider the entity’s activities, expenditure, assets, products, customers, logistics, leased assets, franchises and investments.

All categories should be assessed, even where the first-year estimate uses secondary data or a proxy.

Data quality is not binary. UK SRS S2’s Scope 3 measurement framework prioritises reasonable and supportable information and differentiates direct measurement, estimation, primary data and secondary data. The practical objective is to choose information that is sufficiently representative of the activity, geography, technology and period, explain the estimate and improve the most decision-useful categories.

A practical Scope 3 data hierarchy

Use counterparty- or supplier-specific primary data where it is available, controlled and representative.

Use internal activity data combined with suitable emission factors where direct emissions data is unavailable.

Use secondary data selected for technology, geography and temporal representativeness.

Use spend, average-data or proxy methods transparently for screening or data gaps.

Prioritise improvement according to materiality, uncertainty, concentration and the influence the entity can exercise.

6. Control factors, GWP values and conversions

Emission factors and global warming potential values are controlled reference data. UK SRS S2 generally requires the latest Intergovernmental Panel on Climate Change 100-year GWP values available at the reporting date, unless a jurisdictional authority or exchange requires different GWP values for the entity or an affected part. The factor register should therefore capture source, edition, year, geography, technology, units, heating-value basis, effective dates and superseded versions.

7. Estimates, uncertainty and changes

An estimate is often necessary, particularly for Scope 3. It should not be hidden. Record the population, method, assumptions, source data, factor, uncertainty, known bias, sensitivity and improvement action. Where methods, factors, boundaries or inputs change, assess whether the comparative information must be recalculated or whether the change is an estimate change that should be explained.

8. End-to-end measurement workflow

Confirm the reporting entity and financial-statement consolidation perimeter.

Approve the GHG consolidation approach and disaggregation between the accounting group and other investees.

Build the facility, source and value-chain registers.

Collect activity data and perform completeness, cut-off, duplicate and reconciliation tests.

Select controlled factors, GWP values and units.

Calculate Scope 1 and location-based Scope 2; add contractual information separately.

Screen all 15 Scope 3 categories and calculate included categories using the data-quality hierarchy.

Review Category 15 and financed-emissions requirements where financial activities are present.

Complete independent recalculation, variance analysis and methodology-change review.

Approve the disclosures, evidence index and report wording.

9. Hypothetical group example

10. Illustrative disclosure anatomy

This wording works only if it is supported by a category register, coverage calculation, factor library, boundary memo, methodology file and approval record. It must be adapted to the entity’s categories and facts.

11. Common measurement mistakes

Netting carbon credits or renewable certificates against gross Scope 1, Scope 2 or Scope 3.

Using the consolidated financial perimeter as the entire GHG boundary without assessing leases, investees and the value chain.

Reporting only a market-based Scope 2 figure and omitting the required location-based amount.

Selecting Scope 3 categories by data availability rather than by a complete category assessment.

Using factors without edition, unit, geography or effective-date controls.

Treating estimates as a generic limitation rather than documenting method, uncertainty and improvement.

Failing to separate preparation, review and final approval.

12. Measurement readiness checklist

Reporting entity and accounting-group reconciliation approved.

Facility, source, investee and value-chain registers complete.

Gross Scope 1, location-based Scope 2 and included Scope 3 categories calculated.

Scope 1 and Scope 2 disaggregation prepared.

All 15 Scope 3 categories assessed and decisions documented.

Factors, GWP values and conversions version-controlled.

Estimates and data-quality limitations explained.

Contractual instruments and renewable claims separately controlled.

Independent recalculation and variance review completed.

Evidence index, governance approval and disclosure wording reconciled.

Sources, status and limitation

UK SRS S2 was issued in February 2026 for voluntary use. Any mandatory filing, assurance, relief or presentation requirement must be checked against the applicable FCA, Companies Act, sector or other regulatory route. GHG Protocol source documents are methodology references and should be checked for amendments or revision projects before each reporting cycle.

Editorial and technical production layer