Ship generic Defra

[edit / update model]
This category is deprecated. The latest DEFRA methodology for ship transport can be found here .

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

How to use this category

There is one drill-down in this category. Use the drill-down type to select the type of ship used from the following options.

  • ferry - average RoPax ferry (roll-on roll-off ferry with additional passenger capacity)
  • by foot - pedestrian journey only
  • by car - car journey only
These factors are based on data provided by Best Foot Forward from work for the Passenger Shipping association (PSA) carried out in 2007/2008. The calculated figures are based on ferry service operator provided data on fuel consumption and passengers transported. This does not include any data for passenger only ferry services, which would be expected to have significantly higher emission factors per passenger km.

The distancePerJourney must then be entered as a profile item value. There are three further optional profile item values, isReturn, numberOfJourneys, numberOfPassengers. The isReturn profile item can be set to either true or false (false by default), if true the algorithm doubles the numberOfJourneys. The emissions for one journey for one person are multiplied by the numberOfJourneys and numberOfPassengers (each have a default of 1) to give the total emissions for the people and journeys the user wishes to calculate for.


CO2eEmissionFactor = CO2EF + CO2eEFForN2O + CO2eEFForCH4

CO2e = CO2eEmissionFactor * distancePerJourney * numberOfJourneys * numberOfPassengers

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

distance travelled by ship
is this a return journey? If true, then distance is doubled by the algorithm
use for multiple identical journeys
use if calculating for multiple people