Emission factors 

Emission estimates are usually calculated by applying an emission factor to an appropriate activity statistic. That is:

Emission = Factor x Activity

Emission factors are generally derived from measurements made on a number of sources representative of a particular emission sector. The emission factor database contains the emission factors used in the UK Emissions Inventory as well as factors specifically designed for Local inventories.

The database is designed to provide data and technical information to local authorities that are undertaking a local emissions inventory.


Road transport emission factors in grammes/kilometre can be viewed on the Emission factor for transport page.

This site provides support to emission inventory compliers in the UK and is funded by Defra and BEIS.

References sources for emission factors for many industries are researched by environmental institutions around the world. Many of the key sources of emission factor data that are incorporated into the UK NAEI are as follows:

EMEP/EEA Air Pollutant Emission Inventory Guidebook - 2019


IPCC Guidebook

1996 IPCC Guidelines: http://www.ipcc-nggip.iges.or.jp/public/gl/invs1.htm 
2000 IPCC Good Practice Guidelines: http://www.ipcc-nggip.iges.or.jp/public/gp/english/index.html 
2003 IPCC Good Practice Guidelines for LULUCF: http://www.ipcc-nggip.iges.or.jp/public/gpglulucf/gpglulucf.html 
2006 IPCC guidelines: http://www.ipcc-nggip.iges.or.jp/public/2006gl/index.html

In addition, many of the key data providers such as UKPIA and Tata Steel provide additional information regarding emission factors pertinent to specific fuels and processes.

Page last modified: 20 July 2022