Different versions of the SET are available. You must use the version applicable for the year in which the flight was operated. For example, Version 5.14 is to be used for flights operated in 2024.
The 2024 SET version allows the user to select the fuel conversion factor, as since 1 January 2024 under the EU (EEA) and Swiss ETSs the conversion factor applicable for Jet-A and Jet-A1 has been changed to 3.16, while under the United Kingdom ETS the conversion factor remained 3.15.
The underlying equation in the SET can be obtained by submitting a request using the contact form (the SET equations are subject to a specific data usage agreement).