The first step in using the GHG Protocol methodology is to define the organisational boundary. This involves identifying the sources of emissions that will be included in the emissions inventory. The organisational boundary can be defined in different ways depending on the goals of the emissions inventory. The three most common organisational boundary scopes are:

Scope 1: Includes direct emissions from owned or controlled sources, such as emissions from the combustion of fossil fuels, process emissions, and fugitive emissions (e.g. methane leaks).

Scope 2: Includes indirect emissions from the generation of purchased electricity, heat, or steam consumed by the organisation.

Scope 3: Includes indirect emissions from sources outside the organisation's control, such as emissions from the production of purchased goods and services, transportation, and waste disposal.

Here are detailed explanations and examples for each of the three scopes of greenhouse gas (GHG) emissions:

Scope 1 Emissions

Scope 1 emissions are direct GHG emissions that come from sources that are owned or controlled by the organisation. These emissions are generated from activities that are directly related to the operations of the organisation. Examples of scope 1 emissions include:

• Combustion of fossil fuels: This includes emissions from burning coal, oil, and natural gas to generate electricity or heat, as well as emissions from the use of fuel in vehicles or industrial processes.
• Industrial processes: This includes emissions from chemical reactions or other processes that release GHGs, such as cement production or the use of refrigerants.

Scope 1 emissions are typically the most significant source of emissions for industrial companies or those with significant transportation or energy use.

Scope 2 Emissions

Scope 2 emissions are indirect GHG emissions that come from the generation of purchased electricity, heat, or steam consumed by the organisation. These emissions are generated outside of the organisation's operations but are still associated with its activities. Examples of scope 2 emissions include:

• Purchased electricity: This includes emissions from the generation of electricity purchased from the grid, which can come from a variety of sources, including coal, natural gas, and renewable sources like wind or solar.
• Purchased heat or steam: This includes emissions from the generation of heat or steam purchased from a third party, such as a district heating system.

Scope 2 emissions are often significant for companies with large electricity or heat consumption, like data centres or commercial buildings.

Scope 3 Emissions

Scope 3 emissions are all indirect GHG emissions that come from sources outside of the organisation's control but are related to its activities. These emissions are often the most challenging to identify and quantify, as they may be associated with activities that occur upstream or downstream in the organisation's supply chain. Examples of scope 3 emissions include:

• Purchased goods and services: This includes emissions from the production of goods and services purchased by the organisation, such as raw materials or transportation services.
• Employee commuting and business travel: This includes emissions from employee travel, such as commuting to work or flying for business purposes.
• Waste disposal: This includes emissions from the disposal of waste generated by the organisation, such as landfill gas emissions.

Scope 3 emissions can be significant for organisations with complex supply chains or those that generate significant amounts of waste. They are often the most challenging to manage, as they require collaboration with other organisations and stakeholders.

Overall, understanding the different scopes of GHG emissions is critical for organisations looking to manage their environmental impact. By identifying and quantifying emissions sources, businesses can develop strategies to reduce their GHG footprint and contribute to a more sustainable future.