6 levels of accreditation

The Greenhouse Gas Protocol (GHG Protocol) defines emissions as direct or indirect.

Airport Carbon Accreditation is based on existing international standards in the reporting and accounting of GHG emissions, including the GHG Protocol and ISO 14064. It requires airports to measure their GHG (CO2) emissions in accordance with the GHG Protocol and to get their emissions inventory assured in accordance with ISO 14064 by an independent third party. As such, the programme is consistent, compatible and compliant with national and international management and reporting of carbon emissions.  This helps to ensure that it remains relevant as the carbon management certification standard for the airport industry.

Direct emissions come from sources that are owned or controlled by the reporting entity. Indirect emissions are a consequence of the activities of the reporting entity, but occur at sources owned or controlled by another entity.

The GHG Protocol further categorizes these direct and indirect emissions into three broad scopes:
Scope 1: All direct GHG emissions.
Scope 2: Indirect GHG emissions from consumption of purchased electricity, heat or steam.
Scope 3: Other indirect emissions, such as:
• The extraction, production and transport of purchased materials and fuels
• Transport-related activities in vehicles not owned or controlled by the reporting entity
• Outsourced activities
• Waste disposal etc.