Robert Epsom
June 2015

Update of UK GHG Conversion Factors

Ricardo-AEA has recently completed the 2015 update of UK Government Conversion Factors for Company Reporting (greenhouse gas (GHG) conversion factors). The latest conversion factors are available via an online tool.

What are the changes?
A notable change to the factors this year is the reduction in the electricity factor.

Last year saw many organisations’ Scope 2 emissions increase, even when their energy consumption was reduced. This was due to an increase, of 11%, in the GHG electricity conversion factor last year (2014). The fluctuation was driven by two things. Firstly, a significant increase in the proportion of coal powered electricity generation in the grid mix in 2012 (the inventory year for which the 2014 GHG Conversion Factor was derived). Secondly, this was made more acute by the removal of the 5 year rolling average approach the preceding year. The fluctuations can be shown in the table below.

Year Conversion factor kg CO2e Percentage change
















An example of the impact this had is demonstrated by one of our customers, Debenhams. They identified that despite reducing their electricity consumption (which makes up 77% of their total GHG emissions and 99% of the Scope 2 emissions) by 2% compared to the previous year, the overall Scope 2 emissions increased by 7%.

This year the electricity factor is 6.5% lower than last year. This means organisations whose overall Scope 1 and 2 footprints are made up primarily of electricity use likely to see a substantial reduction against 2014 figures. With 2014 being a peak year for many.

Other changes to factors, which may impact on your organisation, include:

  • An expansion of refrigerants listed, to reflect the changing use of refrigerants and the Kyoto and Montreal protocols. The factors also changed to reflect the update of the global warming potential (GWP) (see below)
  • An addition of a brand new set of aviation factors for international flights between non-UK destinations, to give greater accuracy for organisations who have international operations and substantial air travel
  • An addition of two new bioenergy conversion factors for biodiesel sourced from used cooking oil (UCO) and tallow
  • The factors for this year’s update are now derived from the Intergovernmental Panel on Climate Change’s Fourth Assessment Report (AR4) moving from the Second Assessment Report to remain consistent with UK GHG Inventory reporting under the Kyoto Protocol.

You can see more details on the changes in the ‘What’s new’ tab within the factors spreadsheet.

How should I use the updates?
These factors should be used for calculating carbon footprint for the calendar year 2015.  In the case that you are reporting on an April to March year, for example, the factors from the calendar year in which the greatest portion of your data falls should be applied e.g. the 2015 factors should be applied to data in reporting year 01/04/15 – 31/03/16.  Similarly the 2014 factors should have been applied to data in reporting year 01/04/14 – 31/03/15.  Users that operate a July to June reporting year should apply the newest set of available factors.

Finally, we should point out that CRC Energy Efficiency Scheme reporting is now aligned with UK Government Conversion Factors for Company Reporting and that you should use the 2015 factors for the CRC reporting year 2015-16 (next year) and the 2014 factors for this year’s 2014-15 CRC reporting. You should use the UK electricity generation CO2 only (not CO2 equivalent) factor, which needs to be added to the CO2 only transmission and distribution UK electricity factor, to get the overall factor that should be used for CRC reporting.

If you have any queries about the factors or how to apply them, please do not hesitate to contact our GHG conversion factor and footprinting experts: Rebekah Watson (01235 753 087) and Christine St John Cox (01235 753 084).