Monetary or activity-based approach?
To compute a company's Greenhouse Gas (GHG) emissions, Greenly uses a two-step approach: an initial estimation using a monetary approach and then an activity-based approach to fine-tune the estimation for significant emission sources. For significant emission sources, the activity-based approach should always be preferred.
Activity-based approach
To specify some estimations of GHG emissions, it is necessary to carry out activity-based studies. In this case, physical data (L/gallon, km/miles, kg/lbs, etc.) are multiplied by activity-based emission factors.
These emission factors can be:
Published by public bodies and agencies (e.g. IEA, EPA, UK Government, French Environment Agency, IPCC)
Provided by Life Cycle Assessment (LCA) databases (e.g. Ecoinvent)
Found in LCA studies and research papers
Published by companies
Etc.
Example
A 7.5 t lorry transports 1,500 kg of goods over a distance of 100 km.
The corresponding GHG emissions are computed as follows:
GHG Emissions = 0.378 kgCO2e/t.km (EF of the lorry) * 1.5 t * 100 km = 56.7 kgCO2e
❗ When carrying out activity-based studies, one needs to avoid double counting the same GHG emissions several times:
Monetary approach
Greenly computes the carbon footprint of each expense by analysing, categorising and then multiplying the amount associated with a transaction by a monetary emission factor. The result is an estimation of the carbon footprint (kgCO2e) associated with the expense.