Overview
The Emissions Factors Toolkit (EFT) is published by Defra and the Devolved Administrations to assist local authorities in carrying out Review and Assessment of local air quality as part of their duties under the Environment Act 1995 as amended by the Environment Act 2021.
The EFT allows users to calculate road vehicle pollutant emission rates for NOx, PM10, PM2.5 and CO2 for a specified year, road type, vehicle speed and vehicle fleet composition.
The EFT is updated periodically due to updates to underlying data including vehicle fleet composition and emissions factors. Users are therefore advised to check this page regularly to ensure they are using the most up to date version of the tool for their studies.
Current Version
Documents
EFT v14.1
Released: May 2026 (XLSB, 6 MB)
EFT v14.1 User Guide
Released: May 2026 (PDF, 2 MB, 54 pages)
Details
The current version of the EFT is Version 14.1.
The accompanying EFT User Guide explains in detail the methodology, datasets and assumptions used in the development of the EFT. It consolidates previously available information and guidance on the use of the EFT, and provides information regarding previous versions (changes and updates).
Version 14.1 is identical to Version 14.0 in terms of parameterisation and calculation of emissions, i.e. the emissions outputs are identical.
Changes to Version 14.1 relate to the correction of process errors in the user interface for Bespoke Euro Fleets in the London region.
In order to be confident that your emissions outputs are the most up to date, it is strongly recommended that you use this latest version of the tool.
Version 14 comprises a number of updates relative to v13.1, with the most significant changes being summarised below.
- Update of the Base Fleet Splits for all areas except London, up until 2050.
- The fleet composition projections included in the tool outside of London have been updated in line with the projections developed from the 2023 version of the National Atmospheric Emissions Inventory (NAEI) programme in March 2025. This uses information provided by DfT in December 2024 on future sales and activities of new petrol, diesel and electrically-powered cars and LGVs, combined with future forecasts in traffic (vehicle kilometres) including other vehicle types from DfT’s National Transport Model.
- The default fleet assumptions and projections for London remain unchanged from those that were initially adopted in Version 12.1. These were provided by Transport for London (TfL) , and are representative of London-specific policies, including the expansion of the Ultra Low Emission Zone (London-wide ULEZ) that took place in August 2023.
- Use of the COPERT v5.9.1 NOx, PM and Energy Consumption (used for CO2) speed-based emissions factors, updated from COPERT v5.8, as taken form the European Environmental Agency (EEA) emission calculation tool.
- The emissions factors and methodology for calculating particulate matter (PM) from non-exhaust emissions sources (i.e. from tyre and brake wear, and road abrasion) have been updated in line with EMEP/EEA Emissions Inventory Guidebook 2023.
Version 13.1 is identical to Version 13.0 in terms of parameterisation and calculation of emissions, i.e. the emissions outputs are identical. Changes to Version 13.1 relate only to the optimisation of the model run time.
Version 13.0 incorporates the following changes relative to Version 12.1:
- Update of the Base Fleet Splits for all areas up until 2050.
- The fleet composition projections included in the tool outside of London have been updated in line with the projections developed from the 2022 version of the National Atmospheric Emissions Inventory (NAEI) programme in March 2024. This used information provided by DfT in December 2023 on future sales and activities of new petrol, diesel and electrically-powered cars and LGVs, combined with future forecasts in traffic (vehicle kilometres) including other vehicle types from DfT’s National Transport Model.
- The default fleet assumptions and projections for London remain unchanged relative to those that were adopted in Version 12.1. These were provided by Transport for London (TfL), and are representative of London-specific policies, including the expansion of the Ultra Low Emission Zone (London-wide ULEZ) that took place in August 2023.
- Use of the COPERT v5.8 NOx, PM and Energy Consumption (used for CO2) speed-based emissions factors, updated from COPERT v5.6, as taken form the European Environmental Agency (EEA) emission calculation tool.
- The methodology for calculating indirect CO2e emissions associated with the charging of the batteries of electric and plug-in hybrid cars and LGVs remains consistent with previous EFT versions. The emission factors used in this methodology have been updated in line with the TAG Data Book 2024
- The emissions factors for PM non-exhaust emissions sources (i.e. from tyre and brake wear, and road abrasion) remain in line with v12.1 of the EFT, using information published in EMEP/EEA Emissions Inventory Guidebook 2019.
A list of the data sources used for the development of the current EFT is provided in Appendix D: Data Sources.
Previous Version
Documents
EFT v13.1
Released: March 2025 (XLSB, 5.17 MB)
EFT v13.1 User Guide
Released: March 2025 (PDF, 2.43MB, 47 pages)
EFT v13
Released: March 2025 (XLSB, 5.79 MB)
EFT v13 User Guide
Released: March 2025 (PDF, 2.43MB, 51 pages)
Details
Whilst local authorities are advised to use the latest version of the EFT for all future work, in support of ongoing work, the previous version of the EFT has been provided.
For older versions of the EFT please contact the LAQM Helpdesk for further assistance.
