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Version 3


Version 3 of the calculator (the current version) was published in March 2008.

The main changes from version 2 (more details on the sources pages) are:
  • electricity: the CO2 emission factor was changed to 0.527 kg / kWh (from 0.43 kg / kWh) to allow for grid losses
  • the reduction for renewable sources of electricity was changed from a 90% reduction to a 25% reduction and restricted to certain tariffs
  • natural gas: the CO2 factor changed from 0.19 kg / kWh to 0.203 (to allow for supply inefficiencies)
  • addition of heating oil
  • the factor for cars was changed from 10.5 to 14.3 kg CO2 per gallon (to allow for oil extraction, refinery inefficiency, and motor vehicle manufacture)
  • the basic total for food has been increased from 1.4 to 2.2 tonnes CO2 equ. per person, to incorporate information on methane and nitrous oxide emissions in sources [10] and [12].


Factors unchanged are:
  • the CO2 emission factor for bus travel of 100 g / mile
  • the CO2 emission factor for rail travel of 100 g / mile
  • the CO2 emission factor for air travel of 250 kg CO2 equivalent per hour flying

Version 2


First published Aug 2007 - superseded March 2008

For continuity, this is available here. Because the links have not been updated, some may no longer work.