Generic motorcycle transport

The category /transport/motorcycle/generic contains data associated with the greenhouse gas emissions of representative motorcycle types sourced from UK government agency DEFRA. Data and methodologies concerning motorcycle transport sourced specifically from the latest World Resources Institute Greenhouse Gas Protocol (GHGP) documentation are available in the appropriate subcategories.

Emissions within this category can be calculated on the basis of fuel consumed or distance travelled. Specific fuel-based and distance-based emissions factors are available, although users have the option of deriving their own distance-based emissions factors based on the fuel emissions factors and details of their vehicles fuel consumption.

Selecting motorcycle type

To use this category, specify the vehicle fuel type ('petrol') and size ('small', 'medium', 'large') using the fuel and size drill options respectively.

Calculating by fuel consumed

To make calculations according to the quantity of fuel consumed, users need only specify the fuel quantity using the fuelConsumed profile item value. The returned value represents CO₂ emissions associated with the quantity specified. This is the most accurate method for determining emissions since it makes no assumptions or generalisations regarding the performance, context or efficiency of the vehicle. This calculation method takes precedence over distance-based calculations (see below) - i.e. this calculation will be performed whenever the fuelConsumed profile item value is specified.

Calculating by distance

To calculate according to distance, users need to specify at least a distance value, and select between calculations based on either established, generic emissions factors or those derived from fuel consumption data. Occupancy can be specified (see below]]) but defaults to a sensible value if not set.

Setting the distance

To specify the distance travelled, set the distance profile item value. If users wish to base their emissions calculation on 'typical' motorcycle usage, they can alternatively set the useTypicalDistance profile item value to 'true', which will return a calculation based on the UK average mileage of 3000 miles per year (equating to 4827 km per year or 402 km per month).

Using established emissions factors

To use established emissions factors (sourced from DEFRA, users need only set the distance profile item value. In this case, the returned amount represents CO₂ emissions associated with UK-based motorcycle travel according to the distance specified.

Deriving emissions factors from fuel consumption

Instead of using pre-established emissions factors, users can opt to give a vehicle's fuel consumption. This can either be a user's own estimate (self-calculated or perhaps obtained from their on-board computer) or one provided by the manufacturer, and results in a more accurate estimate of the kg CO₂ emitted. The specified fuel consumption value is used in conjunction with data on the carbon intensity of the respective fuel type taken from The category /home/energy/quantity to obtain a distance-based emissions factor according to:

Factor_{(mass CO2 per distance)} = fuel carbon intensity_{(mass CO2 per volume)} / fuel consumption_{(volume per distance)}

To specify either a manufacturer or self-calculated fuel consumption rate, set either the fuelConsumption or fuelConsumptionOwn profile item values. If the former (i.e. manufacturer) is specified, Discover will inflate the value by 15% to account for real world usage.

Occupancy

Users can set multiple occupancy for motorcycle travel, which 'shares' the vehicular emissions across all passengers. To specify the number of occupants set the occupants profile item value. If no value is set, the calculation will be made on the basis of a single occupant (i.e. the driver) and representing emissions for the entire vehicle journey.