Employee Commuting Emissions Reporting

Reporting emissions from your employees’ commute is part of PPN 06,21
Increasingly required in customer’s sustainability questionnaires
Accuracy in data collection and emissions calculations is essential
Emissions from Home Working can also be requested

Employee Commuting Emissions

Some of your customers might ask you for this data as part of their sustainability questionnaire. If you supply the UK government with £5m or more of goods or services per annum, then you will need to calculate employee commuting emissions as part of your “carbon reduction plan” that you will need to submit when tendering or re-tendering. This reporting requirement is defined in the UK Government’s PPN06/21. and is part of Scope 3 as defined by the GHG Protocol Corporate Standard.

PPN 06/21

Scope 3 guidance Employee Commuting Emissions

How can you do the calculations?

Carry out a survey

You can send out a survey to your employees, either paper based or a word document or even a spreadsheet. The survey would need to ask how many days they travel to work and how often they work from home. You would need them to tell you the modes of travel they use and the distance for each. Some will use multiple modes, for example car to the station, train to the city and tram to the workplace. For some forms of transport finding the actual distances can be difficult. You would then need to collect the responses and then analyse them.

Carry out the calculation

For each mode of transport, you will need to work out the emissions. So, for train journey you will need to work out the kilometres travelled by train and then multiply by the appropriate factor from the UK Government GHG conversion factors for company reporting.

That will give you the “combustion emissions” for that mode of transport. You will then need to add the “well-to-tank” (WTT) emissions to give the total GHG emissions for that segment of the journey. A lot of people commute by car. There are various ways of calculating the GHG emissions for cars.

Using the Vehicle Registration Number

The most accurate is to use the Vehicle Registration Number (VRN) and lookup the grammes of CO2 per kilometre from the DVLA database and the fuel type.   Then apply the WLTP (Worldwide Harmonised Light Vehicle Test Procedure) real world uplift factor, which is based on the vehicle’s year of manufacture. This is necessary because the manufacturers gamed the emissions calculations. The WLTP aims to adjust for this.


Then you need to convert the grams of CO2 into grams of CO2e. This is done by converting the grams of CO2 into litres of the fuel used by the vehicle and then converting the fuel litres into CO2e. You use the litres of fuel to calculate the WTT emissions.

For electric cars, it is assumed that the cars are charged from the electricity grid and so they do have GHG emissions associated with the electricity they use. The Government factors have a page of these factors. This also includes plug-in-hybrids.

Using the UK Government Factors

If the VRN is not supplied, then the government factors have emissions factors analysed by 9 market segments. For example, Lower medium, upper medium and executive. Just allocate the vehicle to the correct market segment and use the relevant factor.  However, do not forget the WTT and the emissions associated with the electricity used by electric cars and plug-in-hybrids. It is feasible to do the calculations on a spreadsheet, if rather time consuming.

Easier Alternatives

Alternatively, you could use GHGi Commuting. This is our online system where each employee completes a series of questions about their commuting journey. They are then presented with a screen which shows the details they have entered. When they confirm and submit their data it shows them the daily emissions from their journey. This immediate feedback is additional motivation for them to complete the survey and so will result in a higher response rate from your staff.

People in your organisation who have “administrator access” will be able to see the individual responses and the total sample data analysed in different ways. For example, by transport mode. If the organisation has a significant sample of employees, the sample results can be scaled up and used as the basis for total commuting emissions of the organisation for the period.  You can also be assured that these rather complex calculations are carried out accurately using the correct factors for the correct period.

GHG Insight

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