Posted on 6th October 2022

Carbon Factors – What are they and why do they matter?

Since we're updating our toolkit methodology, we thought it was a great time to give a quick rundown on what carbon factors are!

What are Carbon Factors?

  • Different activities and products have different amounts of associated GHG (green house gas) emissions
  • Therefore, factors are used in order to calculate the emissions per unit of activity
  • These are measured in CO2e rather than CO2
    • This means all 7 gases outlined within the Kyoto Protocol (which covers the global warming potential of anything that emits c02) are taken into account
    • This includes carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, sulphur hexafluoride, nitrogen trifluoride

Where do the Carbon Factors come from?

  • The factors used within the albert Carbon Calculator are updated annually when the new DEFRA (Department
    for Environment
    Food & Rural Affairs) factors are released
  • Non-DEFRA factors (including textiles, food meals, and others) have been derived from a range of different open-sources including academic journals, reports and articles
  • International factors (for countries outside of the UK) have been provided by an external consultant at Building Research Solutions using sources such as the IEA, EIB and CarbonFootprint 2022
    • These encompass electricity and rail emissions factors

How are emissions calculated using the Carbon Factors?

  • Activity data x Emissions factor = GHG emissions
  • Measured in tCO2e – reporting of all Kyoto protocol gases

Want to know how these help calculate your carbon footprint in our toolkit? Read our latest Toolkit Methodology paper and see the latest changes below


Changes to DEFRA factors

  • Improvement of accuracy of electricity emissions factor – resulting in 16% decrease in Well-to-Tank emissions for electricity factor
  • Removal of factors for open loop source materials

Homeworking emissions

  • Weighting has changed based off of DEFRA methodology and various academic sources – homeworking emissions had previously been weighted 99% to gas emissions factor and 1% to electricity emissions factor – now it is weighted 91% gas-9% electricity

Removal of OOS emissions from biofuels as recommended by our external consultant (impacts emissions factors of fuels)

  • Outside of Scope 1,2,3 emissions
  • OOS corresponds to emissions released by burning biomass and other biofuels which are absorbed during growth phase

Removal of HVO virgin and Renewable Petrol virgin factors as recommended by our external consultant

  • HVO and renewable petrol fuels are inherently derived from waste products anyway
  • No reliable calculation – previously had been calculated by removing OOS factor from the waste factors – OOS factors removed
  • New factors for textiles from SimaPro
  • Radiative forcing factor removed from flight emission factors due to high unreliability
  • Electric buses under Transport and Travel
  • Biodiesel HGV under Transport and Travel
  • Additional Paint factors in Materials section: Now split into type of paint type (water or solvent based) then into type of finish (matt,gloss,undercoat/primer). Previous split had lots of variability
  • Hydrogen as an option for the non-filming spaces section (Previously, this had only been an option for filming spaces section).