This category allows the user to calculate air freight emissions using the latest Defra data and advice.
To use this category, users must specify both a distance and a mass of freight transported. Mass should be specified using the mass profile item value. Users can set freight distance in one of three ways: (1) directly, by specifying an actual distance flown; (2) indirectly, by specifying departure and destination locations; or (3) approximately, by using generic distance categories. In all cases, the returned value represents CO2 emissions attributable to the transported freight over the distance specified.
Specifying departure and destination locations
Users can enter either the latitude/longitude of the departure and destination locations or IATA codes for the respective airports involved in travel. In both cases, CarbonKit calculates the distance based on a 'great-circle' calculation (using the haversine formula), and inflates by 9% to account for congestion and indirect routing.
To use this method, select the auto category via drill down. Next, enter departure and destination locations by setting one of the following groups of profile item values:
- lat1, long1, lat2, long2 (i.e. a pair of latitude and longitude coordinates)
- IATACode1, IATACode2 (i.e. a pair of airport IATA codes)
Depending on the distance calculated, CarbonKit selects the appropriate CO2 emissions factor (kg CO2 per mass km). A short haul emissions factor is used for flights under 3700 km, while a long haul factor is used for those greater than 3700 km. For flights originating and landing within a single country, the domestic emissions factor is used.
Directly specifying a distance
Users can alternatively specify the distance of freighting directly. To use this method, specify the type of flight by selecting domestic, short haul, or long haul via drill down. Next, set the distance flown in the distance profile item value. CarbonKit calculates emissions according to this distance and the selected (domestic, short-haul or long-haul) emissions factor (kg CO2 per mass km).
Generic distance categories
If flight distances, or specific freight departure and destination locations are not available, users can calculate flight emissions based on 'typical' distance categories. CarbonKit follows DEFRA/DECC in assuming the following typical one way flight distances:
- domestic = 463 km
- short-haul = 1108 km
- long-haul = 6482 km
Other Optional Parameters
If users wish to incorporate the effects of radiative forcing, the useRFI profile item value should be set to true (default value is false). The value of the the radiative forcing index can be set using the radiativeForcingIndex profile item value, defaulting to 1.9 otherwise. For an explanation of the radiative forcing index (RFI) see the here.