Sustainability Glossary (Emissions)

Greenhouse gases are those gaseous constituents of the atmosphere, both natural and anthropogenic, that absorb and emit radiation at specific wavelengths that causes the greenhouse effect. There are seven gases listed in the Kyoto Protocol: carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulphur hexafluoride (SF₆) and nitrogen trifluoride (NF₃).

A factor describing the radiative impact of one mass-based unit of a given greenhouse gas relative to an equivalent unit of carbon dioxide over a given period of time.

Greenhouse gas emissions from sources that are owned or controlled directly by the entity (described as direct emissions).

Greenhouse gas emissions from the generation of energy utilised in direct connection to the activities of the organisation but occurring at sources owned or controlled by another entity (supplier).  Purchased electricity is the main emission category in scope 2 emissions.

Greenhouse gas emissions that are a consequence of the activities of an organisation but occur at sources owned or controlled by another entity (supply chain) and which are not classified as Scope 2 emissions.