Scope 3 Emissions Estimator
United Kingdom

Scope 3 emissions reporting in United Kingdom: Streamlined Energy and Carbon Reporting (SECR); Companies (Directors' Report) and Limited Liability Partnerships (Energy and Carbon Report) Regulations 2018

The UK's emissions reporting framework sits at the intersection of domestic legislation and international standards. SECR requires large UK companies and LLPs to disclose energy use and associated greenhouse gas emissions in their directors' report, covering Scope 1 and Scope 2 as a minimum. SECR does not mandate Scope 3 disclosure, but the GHG Protocol encourages it, and entities preparing for international investor expectations increasingly include material Scope 3 categories voluntarily. For UK subsidiaries of EU parent companies subject to CSRD, Scope 3 reporting is mandatory under ESRS E1-6, which requires disclosure of gross Scope 3 GHG emissions broken out by material category. The FCA's Listing Rules require premium-listed companies to make disclosures consistent with the Task Force on Climate-related Financial Disclosures (TCFD) recommendations, which include Scope 3 where material. The UK's own Sustainability Disclosure Standards (UK SDS), based on ISSB S1 and S2, are expected to require Scope 3 disclosure when they come into force, with the FCA consulting on mandatory application for listed companies.

Regulatory context: Department for Energy Security and Net Zero (DESNZ); Financial Conduct Authority (FCA) for listed entities

DESNZ publishes the UK's official GHG Conversion Factors annually (commonly called DEFRA factors, as they were historically published by the Department for Environment, Food and Rural Affairs). These factors cover Scope 1 combustion, Scope 2 electricity, and Scope 3 upstream (well-to-tank) emission factors for all major fuels, as well as spend-based emission factors for procurement categories and transport emission factors by mode. The 2024 DEFRA factors are structured in a downloadable spreadsheet with tabs covering fuels, electricity, transport, waste, water, and materials. For Scope 3 Category 1, DEFRA provides spend-based factors by SIC code that allow entities to convert procurement expenditure into estimated emissions. These are less precise than activity-based factors but provide a starting point for entities without supplier-specific data. The UK Emissions Trading Scheme (UK ETS) sets a compliance obligation for large emitters in power generation, industry, and aviation, but does not directly require Scope 3 reporting. However, UK ETS-regulated entities typically have good Scope 1 data, which supports their supply chain partners' Scope 3 calculations. The Environment Agency oversees environmental permits and pollution reporting under the Environmental Permitting Regulations, which include greenhouse gas reporting for permitted installations.

Practical guidance for United Kingdom

UK entities estimating Scope 3 should use DEFRA conversion factors as the primary emission factor source for UK-based activities. For Category 1, DEFRA's spend-based factors (Table 13 in the 2024 dataset) provide emission intensities in kg CO2e per pound sterling of expenditure by sector. For higher-quality estimates, switch to activity-based factors: kWh for energy, tonne-km for transport, tonnes for waste. The UK electricity grid emission factor for 2024 is approximately 0.207 kg CO2e per kWh (location-based), reflecting the UK's progress in decarbonising its grid through offshore wind and nuclear. This is relevant for Category 3 (upstream electricity emissions) and for estimating Category 11 where products consume electricity in use. For transport, DEFRA provides emission factors per vehicle-km and per passenger-km by vehicle type, fuel type, and size category. For business travel (Category 6), use DEFRA's air travel factors which include separate values for domestic, short-haul, and long-haul flights by cabin class, with and without radiative forcing. For employee commuting (Category 7), the Department for Transport's National Travel Survey provides average commuting distances and mode splits by region. For waste (Category 5), DEFRA's waste disposal emission factors cover landfill (with and without methane capture), incineration (with and without energy recovery), composting, and recycling.

Audit expectations

UK assurance providers performing limited assurance over GHG disclosures under ISAE 3410 or ISAE 3000 (Revised) focus on methodology consistency, factor source documentation, and boundary completeness. The FRC's Thematic Review of TCFD Disclosures (published 2023) found that many UK listed companies disclosed Scope 3 figures without explaining which categories were included, which methods were used, or how data gaps were addressed. The FRC expects entities to disclose the percentage of Scope 3 based on actual versus estimated data, and to explain year-on-year movements. For UK entities reporting under both SECR and CSRD (as UK subsidiaries of EU parents), reconciliation between the two frameworks is expected. SECR uses a financial control or operational control consolidation approach, while CSRD follows ESRS boundary rules. Any differences in reported figures between the two should be explained.

United Kingdom-specific considerations

The UK's grid emission factor has fallen from 0.5 kg CO2e per kWh in 2012 to approximately 0.207 in 2024, driven by the growth of offshore wind (which generated 13.8% of UK electricity in 2023) and the phase-out of coal. This trajectory means Scope 3 estimates for categories involving UK electricity consumption will decrease over time if activity levels remain constant. DEFRA updates its factors annually in June or July. Always use the most recent publication year for your reporting period. The UK's transport fleet is transitioning to electric vehicles, with 16.5% of new car registrations being battery electric in 2023 (SMMT data). Adjust employee commuting estimates to reflect EV penetration in your workforce if you have fleet data. The UK publishes separate grid emission factors for Northern Ireland (which is interconnected with the Republic of Ireland grid and has a different generation mix) and for the main GB grid. For entities with operations in both jurisdictions, apply the appropriate regional factor.

Common inspection findings

The FRC's 2023 TCFD thematic review found that 40% of reviewed companies disclosed Scope 3 without specifying which of the 15 GHG Protocol categories were included or excluded from the reported figure.

DESNZ compliance monitoring identified that some SECR reports understate Scope 2 by using the market-based method without disclosing the location-based figure alongside it, which feeds through to incorrect Scope 3 Category 3 calculations by their customers.

The FCA found that several listed companies disclosed Scope 3 estimates with year-on-year decreases that were attributable to methodology changes (switching emission factor databases) rather than actual emission reductions, without disclosing the restatement.

Assurance providers under ISAE 3410 have noted that UK entities frequently omit well-to-tank (WTT) emissions from Scope 3, despite DEFRA publishing WTT factors for all major fuels. Omitting WTT understates total Scope 3 by 10% to 20% for entities with significant fuel consumption.

The Environment Agency identified inconsistencies between emission figures reported under Environmental Permitting and those reported under SECR for the same installations, suggesting errors in one or both reporting streams that would also affect downstream Scope 3 calculations by customers.