Carbon footprint definitions
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Air and vehicle travel
Emissions from air travel include domestic and international air travel. Vehicle travel includes emissions from rental cars, taxis, fleet vehicles and staff use of private vehicles for business purposes.
Carbon footprint
A carbon footprint is an assessment of the greenhouse gases (GHG emitted by a particular organisation or project, typically expressed for a 12 month period. A carbon footprint includes an assessment of the six greenhouse gases addressed under the Kyoto Protocol, and can include other greenhouse gases if desired. A carbon footprint describes GHG emissions as carbon dioxide equivalents (CO2e); that is, the global warming potential (GWP) of the gas, relative to CO2.
Direct emissions
Direct GHG emissions are emissions from sources that are owned or controlled by an organisation.
Electricity
Emissions from electricity used in our offices include direct (scope 2) emissions and emissions from leased assets such as lifts and some HVAC equipment.
Greenhouse gases
The greenhouse gases accounted for within carbon footprint calculations are those six listed in the Kyoto Protocol: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulphur hexafluoride (SF6). In order to compare gases against a common basis, the universal unit of measurement ‘CO2 equivalent’ is used. This standardises gases in terms of their global warming potential relative to carbon dioxide, and is expressed in terms of the GWP of one unit (1 kg) of CO2e. For example, methane (CH4) has 35 times the global warming potential of CO2; therefore 1 kg of methane would be expressed as 35 kg of CO2e.
Indirect emissions
Indirect GHG emissions are emissions that are a consequence of activities of an organisation but occur at sources owned or controlled by another organisation.
Scope of emissions
In accordance with carbon footprint protocols, emissions are divided into three “scopes”, as follows:
- scope 1: direct emissions controlled or owned by Transpower (such as fuel combusted in fleet vehicles)
- scope 2: indirect emissions from consumed electricity
- scope 3: other indirect emissions arising from the consequences of Transpower’s activities, but generated by sources not owned or controlled by Transpower (e.g. emissions arising from staff air travel).
Companies must separately account for and report on their scope 1 and 2 emission sources. Reporting on scope 3 emissions is optional.
SF6
SF6 (Sulphur Hexaflouride) is the most potent greenhouse gas, having 23,900 times more global warming potential than the equivalent amount of CO2.
Transpower holds approximately 80 percent of the SF6 in the country. The gas is used as an insulator in substations, primarily in gas-insulated switch gear and circuit breakers, although it can be found in other equipment.
Transpower, since signing in 2004, is a party to a Memorandum of Understanding between the Government (Ministry for the Environment) and major SF6 users such as Tiwai Comalco Aluminium Smelter and Genesis Energy. Under the agreement Transpower commits to keeping SF6 emissions below 2 percent of installed nameplate capacity, and to report annually on its SF6 inventory and emissions.
Waste
Office based waste includes all waste sent to landfill from Transpower offices – organic and inorganic. This category has been included primarily because of the potential to influence behaviour through introducing waste minimisation practises in Transpower offices. It is expected that this will positively influence behaviour in other categories.
A recycling system already exists in all Transpower offices, but not all offices have the facility to separate green (organic) waste. A national waste audit undertaken in October 2009 identifies a number of initiatives that can be implemented to reduce waste to landfill. Recommendations from this audit have been implemented.
