In Life Cycle Assessment (LCA), there are three scopes that are used to define the boundaries of the study:
Scope 1: Includes direct emissions from sources that are owned or controlled by the company conducting the LCA, such as emissions from on-site combustion of fossil fuels or emissions from company-owned vehicles.
Scope 2: Includes indirect emissions from the generation of purchased electricity, heat, or steam used by the company conducting the LCA. These emissions occur at sources that are not owned or controlled by the company, such as a power plant that supplies electricity to the company.
Scope 3: Includes all other indirect emissions that occur in the entire life cycle of a product, from the extraction of raw materials, to the production of components and materials used in the product, to the use and end-of-life phases. These emissions occur from sources that are not owned or controlled by the company conducting the LCA, such as the transportation of raw materials or the disposal of the product at the end of its life.
Scope 3 emissions are typically the largest source of emissions in a product's life cycle, but are also the most difficult to quantify and control since they often involve multiple actors in complex supply chains. Accuracies are improved drastically when the product manufacturer has EPDs of its main suppliers.