Calculation of footprint for transport

Calculate the transport footprint for a person based on travelling habits. This can be used to nudge users towards more sustainable travel.

Inputs

This endpoint receives as optional input:

• a data source to base calculations on
• a list of travelling habits
  • Number of household members (influences default number of vehicles)
  • Number and type of vehicles owned by household (influences choices for weekly transport)
  • Distance to work or school 
  • Number of days per week using different modes of transport to work or school
  • Weekly distance travelled for social purposes
  • Holiday trips (specified by ranges as regional/countrywide/continental/global with the assumed distance of each range being 100/350/1500/7000 km)
• the date for which the footprint should be computed

The more questions a user answers the better we understand the user’s behaviour, giving a more accurate footprint estimation. All inputs are optional and missing values are defaulted. If no input date is given, the current date is used as default. If no habits are provided the calculation will assume default answers, i.e. that the user’s travelling habits are similar to an average person from the data source you have specified. This can be used to compare a person's transport footprint to the average person in a country.

Outputs

This endpoint returns a breakdown of an annual transport footprint in kilos of CO2e, with absolute and percentage values, aggregated by purpose (work, social and holiday).

If you have not submitted optional information, the footprint of an average person for the chosen data source will be returned.

Calculations

Transport multipliers

The multipliers for different modes of transport have been taken from various studies, as detailed in the Convert transport section. National transportation statistics such as average distance to work, average speed of various modes of transport in the city, public transport use etc. are obtained from public databases and national surveys (SSB, UK Transport National Survey, Norwegian Transport Survey) etc. The statistics are used as default values in case the user does not specify an input, as it most closely represents the behaviour of an average citizen.

The input date also affects the calculations. We account for technology changes over time (more efficient cars, higher share of electrical vehicles in the total vehicle fleet) and temporal effects (higher energy prices and emissions intensity in winter) and its climate impact on your footprint. For example, the emissions intensity of an average car five years ago was much higher than the emissions intensity today. Hence, the footprint of a journey taken five years ago would be much higher than the footprint of a journey taken today.

Defaulting inputs

The footprint calculations support providing partial input of variables. If you provide no input for the number of vehicles owned, your travel patterns and preferred mode of transportation and so on, we will make an educated guess based on household factors and national averages, and fill in a default value. If you provide only partial input, let’s say you drive to work once a week, we assume you only travel to work once per week. The number of days you travel to work with other modes of transportation, such as electric cars or public transport, will be set to zero. The same goes for the number of kilometres travelled per week for social purposes. We essentially assume that if the user is providing specific information about their travel preferences, they are providing complete information. Therefore, it is advised to provide the complete set of inputs matching your habits to the most accurate possible footprint.

Work travel

To calculate the work transport footprint, the total weekly kilometres travelled are calculated based on the distance to work or school. Unless the number of days travelled using different modes of transport is specified, the total weekly kilometres are allocated to different modes of transport based on the relationship between number of household members and number of cars owned. Once the kilometres travelled using each mode of transport are calculated, they are multiplied with the emission factor of that transportation mode to get the weekly footprint. This number is further multiplied by 48 weeks, assuming 4 weeks of vacation, to get the total yearly footprint.

Social travel

An average number of kilometres per week travelled for social reasons is either assumed or specified by the user. If the user does not specify kilometres per mode of travel, the kilometres are automatically divided between private and public transport according to the users’ vehicle ownership. The yearly footprint is then calculated using multipliers and assuming 52 weeks in a year.

Holiday travel

For holiday travels, the user can specify the number of trips of different distance ranges (e.g. domestic/continental/global). We then use an assumed distance in kilometres for each trip type to calculate the total number of kilometres travelled by different modes of transport per year for holiday purposes. At last, the kilometres are multiplied with the multiplier of the relevant mode of transport to obtain the footprint.