Commuting emissions result from the transportation of employees between their homes and their regular place of work. According to the Greenhouse Gas Protocol, emissions from employee commuting are categorized as Scope 3 (Category 7) emissions.
Altruistiq supports two calculation methodologies for calculating commuting emissions data; one using actual transport data collected from employees, and the other which uses employee numbers and working days to estimate emissions. This article focuses on the methodology used for the estimated methodology.
Calculating Emissions using the Estimated Passenger-Distance Method
Altruistiq’s commuting emission factors are applied to the “Person.Days” calculated from the uploaded data using the following formula:
Number of Employees*(Days Worked in Period - WFH days in period)
Our commuting emission factors represent average emissions intensity per person per day of commuting in a given country and are developed using a model based on secondary commuting and emissions data.
We use two sets of data in order to calculate the emission factors:
1 ) Commuting data - our source for this is Numbeo, a citizen’s science datasource that aggregates traffic and travel data globally. This includes over 40,000 datapoints from survey respondents from 207 countries and territories.
The data metrics we take from this are:
Share of commuters travelling by different transport type.
Distance travelled for each transport type.
2) Emissions data - our source for this is the UK Government Conversion Factors. We take the Business Travel land emission factors for relevant transport that match the Numbeo transport types.
This includes emissions covering both lifecycles:
Vehicle Use - emissions created by the vehicle through mobile combustion.
Well to tank - upstream extraction of fuels used in transport.
We then calculate the weighted average of emissions per country, based on the split of commuting modes and distances.