How are staff commuting emissions calculated?

This article summarises the key parameters used in the model to calculate emissions from staff commuting

Staff Commuting
Staff commuting to an office location is included in an organisations Scope 3 emissions. In many cases, your organisation may not have an exact breakdown of the number of staff commuting per mode. The following models have been designed to support the calculation of staff commuting emissions.

The Data
1. Commuter Split Model
This model requires a user to input the number of staff that drive into the office. The remaining staff are split between the various commuting modes using average commuting data from the Australian Bureau of Statistics. Other commuting modes include: bus, ferry, motorbike/scooter, train, and light rail/tram.

Average commuting distances for each city and mode are used to determine the total kilometres travelled. The resulting emissions are calculated by multiplying the total kilometres travelled by the relevant emission factors.

2. Modal Split Model
This model requires a user to input the number of staff that drive, take a motorbike/scooter, or use public transportation to commute to work. Average commuting distances for each city and mode are used to determine the total of kilometres travelled. The resulting emissions are calculated by multiplying total kilometres travelled per mode by the relevant emission factors.

The Calculation Method
The following calculation method is used to estimate emissions from staff commuting:

GHG = (average driving distance * average car fuel efficiency * fuel energy content * emission factor) + Σ all other modes (staff public transport km * % mode split * emission factor)

Example: Calculation of emissions

A company based in Sydney, Australia has 2 FTE which drive and 8 FTE where commuting modes are unknown for the month of January.

Pathzero has stored the relevant emission factors for converting km travelled by mode into CO2-e as well as average commuting distances, percentage split, and other relevant conversion factors.

The resulting calculation is:

Staff driving emissions = 32.38 km * 0.108 litres/km * 0.342 GJ/litre * 68.8 kg CO2-e/GJ = 8.228 kg CO2-e

Staff bus emissions = 22.14 km * 15.20% * 0.1031 kg CO2-e/km = 0.347 kg CO2-e

Staff ferry emissions = 24.88 km * 0.99% * 0.0187 kg CO2-e/km = 0.00449 kg CO2-e

Staff motorbike/scooter emissions = 26.58 km * 1.63% * 0.1134 kg CO2-e/km = 0.0464 kg CO2-e

Staff train emissions = 43.02 km * 40.5% * 0.0369 kg CO2-e/km = 0.644 kg CO2-e

Staff tram/light rail emissions = 17.10 km * 0.34% * 0.02991 kg CO2-e/km = 0.00176 kg CO2-e

GHG = (8.228 kg CO2-e * 2 FTE * 20 days) + (1.047 kg CO2-e * 8 FTE * 20 days) = 496.62 kg CO2-e