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Air Travel
Measuring GHG emissions from air travel is complicated, and occasionally uncertain. Variations in calculations will change the price between providers.
A number of factors must be taken into account for air travel, that do not feature for car travel or home consumption. Key factors for air travel, for instance, include contrails, cloud type and additional greenhouse gases besides CO2. These complex factors affect the overall warming impacts of air travel. To allow comparisons with emissions from other sources a concept of radiative forcing is used. This measures the rate at which a given atmospheric gas alters radiation that is entering the atmosphere. The Intergovernmental Panel on Climate Change has produced a detailed report about Aviation and Global Atmosphere. http://www.grida.no/climate/ipcc/aviation/index.htm Total radiative forcing of air travel is one to five times larger in the stratosphere than in the troposphere, and an average of 2.7 has been used by the IPCC. More recent work, however, suggests that this may be too high and we have used a figure of 1.9 as a best estimate.
Allowances for complicated factors such as wind, other atmospheric conditions, detours, holding patterns (which we have excluded for domestic flights), extent of cargo, and taxiing have been covered by using average figures calculated from existing extensive databases.
More fuel is consumed during take-off and climbing, therefore shorter flights have a lower overall fuel efficiency. But the efficiency gain during long flights is partly offset by the added weight of the fuel. In Australia, all main domestic flights are long-haul and we have used the more conservative long-haul factor in our emissions modeling.
Other factors besides radiative forcing include fuel consumption. What you should pay will depend on whether you travel economy or business, whether the plane is full or not, and plane type. Where these figures are not entered into the fields provided we use averages.
Car Travel
CO2 emissions calculations for vehicles are straightforward – they depend only on the type and quantity of fuel burned. Other greenhouse gases emitted comprise a relatively small proportion of overall transportation emissions, therefore only CO2 emissions estimates are included.
Home
Calculating electricity consumption through electricity bills or meter records is the most accurate approach. The emission factor of electricity depends on the source of energy used for creating the electricity, which varies from state to state and internationally, hence location needs to be identified.
Small Businesses
Watch this space for this important calculator which can be tailored to form your company’s GHG inventory! It will suit companies in the service sector, defined as those that do not undertake any manufacturing activities, for example, banks, insurance, retail, law firms, real estate, publishing, shipping, marketing and consulting companies.
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