Emissions Factors Toolkit

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 NO_x, PM₁₀, PM_2.5 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 v13

Released: March 2025 (XLSB, 5.79 MB)

EFT v13 User Guide

Released: March 2025 (PDF, 2.43MB, 51 pages)

Details

The current version of the EFT is version 13.

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 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 NO_x, 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.

Version 12.1 incorporates the following changes relative to Version 12.0.1:

• Bug Fix – Fixed an issue whereby emissions from Diesel Hybrid Cars, Petrol Hybrid Taxis and Electric Taxis may have returned marginally higher emissions than expected in certain scenarios.
• Bug Fix – Fixed an issue regarding the calculation of NO_x and CO₂ exhaust emissions for Euro V HDVs equipped with Exhaust Gas Recirculation (EGR) and Selective Catalytic Reduction (SCR) technologies.
• User Interface – Amended headers when selecting ‘All Vehicle Types’ on the Input Data sheet to show ‘E85 Bioethanol Cars’ and ‘E85 Bioethanol LGV’ instead of ‘Biomethane Cars’ and ‘Biomethane LGVs’.
• User Interface – Resolved an issue whereby a message may appear requesting link lengths to be input when selecting either CO₂ pollutant outputs or ‘Annual Link Emissions’ outputs for other pollutants, even when link lengths had been inputted.
• User Interface – Included a new message box to notify users of successful export, along with file location and filename, when using the ‘Export Outputs’ option

Previous Version

Documents

EFT v12.1

Released: August 2024 (XLSB, 4.14MB)

EFT v12.1 User Guide

Released: August 2024 (PDF, 2.3MB, 48 pages)

EFT v12.0.1

Released: December 2023 (XLSB, 4.1MB)

EFT v12.0.1 User Guide

Released: December 2023 (PDF, 2.16MB, 47 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.