Car Defra By Size


This category is deprecated. The latest DEFRA methodology for car transport by size can be found here .

This category allows users to calculate greenhouse gas emissions from a car journey from indicating the car's size. The methodology follows the latest Defra emission factors and advice.

How to use this category

There are two drill-downs in this category. Use the drill-down fuel to select the fuel used by the vehicle from the following options.

  • petrol
  • diesel
  • petrol hybrid
  • lpg
  • cng
  • average - for use if fuel is unknown
The second drill-down, size, selects the approximate size of the vehicle. Select from the following options.

  • small
  • medium
  • large
  • average - for use if fuel is unknown
The small option only exists for petrol and diesel cars.

The distance must then be entered as a profile item value. There are four further optional profile item values, occupants, ownFuelConsumption, numberOfJourneys and totalFuelConsumed.

The occupants profile item value is used to enter the number of people in the car for the selected journey (default 1). The emissions are then divided by the number of occupants in order to return the fraction of the emissions due to each person. The ownFuelConsumption can be entered if the user has a reliable value for their vehicles fuel consumption (default units of km/L). If this is entered then it overrides CarbonKit's default emission factors for the selected vehicle. The algorithm then divides the fuel emission factor, from the Fuel_Defra category, by the users ownFuelConsumption and multiplies by the distance. The numberOfJourneys profile item value (default 1) can be used if the specified journey has been repeated a number of times; the emissions for one journey are multiplied by this value. Finally, totalFuelConsumed can be entered if the volume of fuel used for the entire journey is known. In this case the volume of fuel is multiplied by the appropriate emission factor in the Fuel_Defra category.


If no fuel consumption information entered

CO2eEmissionFactor = CO2EF + CO2eEFForN2O + CO2eEFForCH4

CO2e = CO2eEmissionFactor * distance * numberOfJourneys / occupants

If ownFuelConsumption entered

CO2eEmissionFactor from business/energy/fuel

CO2e = (CO2eEmissionFactor / ownFuelConsumption) * (distance / occupants) * numberOfJourneys

If totalFuelConsumed entered

CO2eEmissionFactor from business/energy/fuel

CO2e = CO2eEmissionFactor * totalFuelConsumed

The algorithm returns a value of kgCO2e for the particular journey, per occupant. This value includes contributions from carbon dioxide, nitrous oxide and methane.

GMOFSHI36EBF average, average
P1YQI9ZGQR5Y cng, average
WKGQ0HIDFFS9 cng, large
1AAZQR8IOP7V cng, medium
FODUZ6C8U5AZ diesel, average
CKQTA2LX3N4H diesel, large
EVF5DEUP5SK4 diesel, medium
4IC1O4N4DUED diesel, small
3JWMDUZN57OU lpg, average
L65DWKKOEKQF lpg, large
8W74BM76QIBQ lpg, medium
BEOHHZRLYMHT petrol hybrid, large
8Q2GPQKSY870 petrol hybrid, medium
2WVQWO3ZSZMT petrol, average
017BWCF8H91W petrol, large
0KSAMSQ5M0DI petrol, medium
3Y5X4VAA9TZL petrol, small
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Name: Car_Defra_By_Size
Full path: /transport/car/generic/defra/bysize
Parent Category: Generic car transport Defra