The GHG Protocol, the most commonly used methodology for calculating and reporting emissions for organizations in the US and worldwide, has defined three scopes of emissions. Scope 1 emissions, commonly referred to as direct emissions, arise from sources that are controlled or owned by an organization. For example, emissions associated with fuel combustion in boilers, furnaces, vehicles, or from releases of refrigerants to the atmosphere are all considered Scope 1 emissions. Scope 2 emissions are indirect emissions associated with the generation of purchased electricity, steam, heat, or cooling by the organization.
Scope 3 emissions, also known as value chain emissions, encompass indirect emissions that occur in the value chain of the organization, both upstream and downstream from its operations. The GHG Protocol has defined 15 categories of Scope 3 emissions, and not all 15 will be relevant to every organization. Examples of Scope 3 emissions include emissions from business travel, employee commuting, and transportation and distribution.