Greenhouse gas conversion factors for company reporting

2012 Guidelines to Defra / DECC's GHG Conversion Factors for Company Reporting
Annex 1 - Converting from fuel use to carbon dioxide equivalent emissions
Last updated: Apr-12
How to use this Annex
1) Identify the amount of fuel used for each fuel type
2) Identify the units. Are you measuring fuel use in terms of mass, volume or energy?
3) If you are measuring fuel use in terms of energy is your unit of measurement net energy or gross energy? (Please see paragraph below on net and gross energy. In the event that this is unclear you
should contact your fuel supplier).
4) Identify the appropriate conversion factor that matches the unit you are using. If you cannot find a factor for that unit, Annex 12 gives guidance on converting between different units of mass, volume,
length and energy.
5) Multiply the amount of fuel used by the conversion factor to get total emissions in kilograms of carbon dioxide equivalent (kg CO 2 e). The excel spreadsheet calculates this automatically following your
entry of the amount of fuel used into the appropriate box.
Note: In the UK biofuels are added to virtually all of the transport fuel sold by filling stations (and by most fuel wholesalers) and this has the effect of slightly reducing the greenhouse gas emissions of
the fuel. This is reflected in the emission factors below. For fuel purchased at filling stations or obtained from private commercial refuelling you should use the factor labelled "average biofuel blend"
unless you know the biofuel content is higher or lower than average. In this latter case, if you are purchasing pure petrol or diesel which you know has not been blended with biofuels then you should
use the factor labelled "100% mineral fuel", or alternatively use the bespoke biofuel blend calculations provided in Annex 9, Table 9b.
Four tables are presented here, the first of which provides emission factors by unit mass, and the second by unit volume. Tables 1c and 1d provide emission factors for energy on a Gross and Net CV
basis respectively; emission factors on a Net CV basis are higher (see definition of Gross CV and Net CV in italics below). It is important to use the correct emission factor, otherwise emissions
calculations will over- or under-estimate the results. If you are making calculations based on energy use, you must check (e.g. with your fuel supplier) whether these values were calculated on a Gross
CV or Net CV basis and use the appropriate factor. Natural Gas consumption figures quoted in kWh by suppliers in the UK are generally calculated (from the volume of gas used) on a Gross CV basis -
see Transco website: http://www.transco.co.uk/services/cvalue/cvinfo.htm. Therefore the emission factor in Table 1c (Gross CV basis) should be used by default for calculation of emissions from
Natural Gas in kWh, unless your supplier specifically states they have used Net CV basis in their calculations instead.
Gross CV or higher heating value (HHV) is the CV under laboratory conditions. Net CV or 'lower heating value (LHV) is the useful calorific value in typical real world conditions (e.g. boiler plant). The
difference is essentially the latent heat of the water vapour produced (which can be recovered in laboratory conditions).
Annex 1 Scopes & Boundaries:
Scope 1: Direct emissions of CO 2 , CH 4 and N 2 O from the combustion of fuel.
Scope 3: Indirect emissions associated with the extraction and transport of primary fuels as well as the refining, distribution, storage and retail of finished fuels.
Emission factors are based on data from the JEC Well-To-Wheels study, for further information see the following links:
http://iet.jrc.ec.europa.eu/about-jec/
http://iet.jrc.ec.europa.eu/about-jec/downloads
How were these factors calculated?
For further explanation on how these emission factors have been derived, please refer to the GHG conversion factor methodology paper available here:
http://www.defra.gov.uk/environment/economy/business-efficiency/reporting/
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