Carbon Footprint

The carbon footprint is a measure of the total amount of carbon dioxide (CO2) and other greenhouse gas emissions that are directly or indirectly caused by an activity or that are accumulated over the life span of a product, person, and organization—or even a city, state, or nation. The term carbon footprinting refers to a measure by which a company or individual can calculate how much carbon or CO2 equivalents they have produced and emitted during a project or time period. The full carbon footprint of an organization (including municipal agencies) encompasses a wide range of emissions sources, from direct use of fuels to indirect impacts such as employee travel or emissions from other organizations up and down the supply chain. When calculating an organization's footprint, it is important to try to quantify as full a range of emissions sources as possible to provide a complete picture of the organization's impact. To produce a reliable footprint, it is important to follow a structured process and to classify all the possible sources of emissions thoroughly. A common classification is to group and report on emissions by the level of control that an organization has over them. A standard classification is defined by the Greenhouse Gas Protocol, a widely used standard for corporate emissions’ reporting produced by the World Business Council for Sustainable Development and the World Resources Institute. Three main types of emissions exist:

• 1.
  Direct emissions that result from activities that the organization controls: The majority of direct emissions result from combustion of fuels that produce CO2 emissions (e.g., the gas used to provide heating for a building). Some organizations also directly emit other greenhouse gases (e.g., the burning and production of cement).
• 2.
  Emissions from the use of electricity: Workplaces generally use electricity for lighting and equipment. Electricity generation comes from a range of sources, including renewables. In the United Kingdom, however, around 75 percent of the nation's electricity is produced through the combustion of fossil fuels such as coal and gas. Although not directly in control of the emissions, by purchasing the electricity the organization is indirectly responsible for the release of CO2.
• 3.
  Indirect emissions from products and services: Each product or service purchased by an organization contributes toward emissions. The way the organization uses products and [Page 50]services therefore affects its carbon footprint (e.g., a manufacturing company is indirectly responsible for the CO2 that is emitted in the transport of the raw materials, as well as for emissions from the distribution, use, and disposal of its finished products).

Calculating a carbon footprint incorporating all three types of emissions can therefore be a complex task. In addition, published carbon footprints are rarely comparable for several reasons:

• Despite emerging international standards, not all organizations follow the same methodology to calculate their carbon footprint.
• Some carbon footprints are expressed on a time period basis, such as annually, and some are measured on a unit basis, such as per product produced.
• Carbon footprints are usually calculated to include all greenhouse gases and are expressed in tons of CO2 equivalent (tCO2e). Some, however, calculate the carbon footprint to include CO2 only and express the footprint in tCO2 (tons of CO2).