For the majority of the emissions categories that we offer, you have the option to choose from a number of different calculation methods. Each of the methods however, are associated with a different degree of accuracy, and thus you should always strive to use the calculation method with the 'Recommended' badge assigned to it. Additionally, the methods are listed from most to least accurate, from top to bottom.
Below you can see an example of the available calculation methods for the Mobile combustion emission category. You can see that the "Actual fuel consumption" method is recommended as it has the 'Recommended' badge, highlighted here in yellow.
What is a calculation method?
Calculating emissions for a particular emission category can usually be done in more than one way while each method typically yields more or less accurate emission estimations.
Which method to pick mainly depends on the availability of your data and/or the efforts you are willing to invest in data sourcing.
Keep in mind that there are emission categories where you might need to use more than one calculation method to report different types of activity data. If the activity data that you have available to you does not fit the recommended calculation method, read through the Requirements for each method and choose the one that best fits your needs. After you complete your first round of data collection, you can start to try to see how you might be able to collect the necessary data to be able to use the recommended method.
Example: Mobile combustion
Imagine you operate a company-owned and combustion-based vehicle fleet that you would like to calculate emissions for. You know that you can choose from different methods, so you first talk to your vehicle fleet manager to understand what data is available for your vehicle fleet.
Your vehicle fleet manager confirms that they are able to send you a monthly update regarding distances driven per vehicle - which is already being recorded for accounting purposes.
From your contact in the Finance department, you learn that data on fuel consumption is also available; partially electronically through fuel cards and partially through paper-based receipts from the gas stations (which some employees forget to hand in though).
Looking at the available calculation methods for Mobile Combustion, you recognise that both of the available methods are applicable based on the data you have available.
Which one do you pick?
There are multiple angles from which you can decide on a method:
From a carbon accounting perspective, you would pick the method "Fuel consumption" since it is the Recommended option and most accurate.
From a data availability perspective, you might opt for "Average fuel consumption | Distance driven" since you expect that sourcing fuel consumption data from the paper receipts will take more time.
This perspective may be strongly influenced by the materiality that the respective emission category contributes to your overall Corporate Carbon Footprint. If you expect that your Mobile Combustion emissions make up a significant portion of your overall company emissions (e.g. if you have a substantial or heavily-used vehicle fleet) it will be worth taking the extra effort to have more accurate results.
Finally, you could also consider mixing different calculation methods and, for example, choose:
"Fuel consumption" for the vehicles where the required data is reliably available via the tank card data and pick.
"Average fuel consumption | Distance driven" for the vehicles where drivers do not use a tank card.
To summarise the process of choosing a calculation method, let's visualise it: