Apply Life Cycle Assessment (LCA) information

Life cycle assessments (LCA) is a methodology for assessing the environmental impacts associated with all stages of a product, process or a service. If you want to learn more about LCA in general, these two links might be useful [1] [2]

When calculating the emissions from an activity, you can split the activity into several sub-activities. Depending on your needs, you might want to include all or only some of these activities.

Let us use the example of burning fuel in a car. CO2e is emitted when the fuel is combusted inside the vehicle, but extracting the fuel from the earth, refining it and shipping it to the gas station also emits CO2e.

Depending on your needs, you might need to only include the CO2e from the combustion of the fuel, or you might be interested in the more complete number that also includes fuel extraction and transportation.

Sources handle LCA activities differently. One source might list emission factors for the two aforementioned activities separately. The combustion of the fuel might have its own emission factor with the LCA activity listed as fuel_combustion, and the second one activity would have an emission factor with the LCA activity listed as well_to_tank

Another source might not perform this separation, and would instead only provide one emission factor that encompasses both activities. This activity might have a life-cycle activity called fuel_upstream-fuel_combustion that covers both the upstream (well-to-tank) activity and the combustion of the fuel.

Not all sources specify what sort of LCA activities they consider at all. These LCA activities are listed as unknown

If you do not explicitly filter on an LCA activity, Climatiq will always pick the newest, and then the highest emission factor. That means that as a rule-of-thumb, if multiple factors exist with different LCA activities, Climatiq will tend to pick the one with the most comprehensive LCA activity, as that emission factor will also have the highest CO2e. If you have more stringent needs for what LCA activities you need to consider, you should explicitly filter on the lca_activity field, and refer to the different sources to see what they consider to be part of each lca_activity.