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Simple Carbon Calculator |
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This page contains a simple carbon calculator for use by UK organisations based upon the recommended conversion factors provide by Defra as part of its Environmental Reporting Guidelines. |
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Individuals wanting to calculate their carbon footprint are recommended to go to the Carbon Workout section of the NEF website.
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Directions:.
Which electricity factor should we use?
This table offers a number of factors for converting electricity to its carbon dioxide equivalent. The default one is based on a five year rolling grid average to 2007 (0.54055), and is recommended unless you have a good reason to use another factor: the average figure is uses the total UK electricity generation mix of coal, nuclear and gas turbines, as well as renewables. However, if : you are using this table to estimate emissions in line with Climate Change Agreements (CCAs), then the marginal, lower figure (0.43) should be used this is based on marginal emissions (which are usually those from high efficiency Combined Cycle Gas Turbines - CCGT). This figure may also be the more appropriate figure when estimating energy savings. All figures exclude the incremental emissions due to other GHGs such as CH4 and N2O.
For electricity generated from renewable sources, zero carbon dioxide emissions may be used if the supply has been generated onsite. It was formerly acceptable to use zero for electricity bought on a green tariff certified by OFGEM, but in June 2008 Defra announced that for 2008/9 onwards, this should use same average factor as for grid electricity. This is as it had become difficult to demonstrate that paying for a renewable electricity tariff was leading to additional installed renewables capacity or to extra CO2 reductions since suppliers have been required to buy some electricity from renewable sources to meet their Renewables Obligation. Although we allow a zero factor for onsite renewables generated, this should only be used if ROCs are not sold. However for the reverse calculation back to energy, we have omitted renewables from the kWh totals for most users.
For other countries, the electricity component would need to be adjusted based upon primary fuel mix. Defra now publishes a table of factors for 56 countries - only a few key countries where Britons have holiday homes or major manufacturing centres are included above.
What do these figures mean?
Around half UK CO2 emissions come from industry and commerce, including the use of transport to deliver goods. This calculator should help smaller companies identify their carbon footprint, based on available records of energy used. Larger organisations, which have already taken steps to reduce energy use and their carbon footprint, are advised to find out more about the Carbon Trust Standard (which superseded the Energy Efficiency Accreditation Scheme in 2008), which uses a more sophisticated carbon calculation. Individuals are recommended to use the Carbon Workout instead, although the table above could be used to estimate emissions from your fuel bills.
Where do these figures come from?
All data in this table is based upon the official 2009 guidelines from the Department of Environment, Food and Rural Affairs, originally published in 2001. Emissions for other fuels can be found on Defra's Environmental Reporting page. Figures have been updated to include the July 2009 data where applicable. This table only gives some of the main conversion factors, and CO2 equivalents are given on a Gross Calorific Value basis: Defra intends to move to a net CV basis in the near future which will slightly increase emission factors from natural gas and LPG.
The car mileage figure is based upon an average UK family car returning 29mpg. If your car fleet returns better figures on average, (or you driving a smaller car achieving (say) 40mpg, or regularly share a car) then you could adjust the mileage accordingly to estimate CO2 emissions. In choosing a figure, it's worth bearing in mind that official published fuel consumption figures are calculated under ideal conditions (a warmed up engine, no sharp braking or accelerating) and can be at least 10-15% better than achieved by most drivers in real life.
Aeroplane emissions are very hard to estimate. The figure above is based upon short-haul (European) flights in economy class - add up to 50% for business class travel with lower seat densities. However there is some evidence that there is at least as much Global Warming effect again from other aircraft emissions in the upper atmosphere, such as ozone created from NOx or condensation trails, than solely from the CO2 emitted on the journey. Our personal Carbon Workout allows you to estimate emissions from specific journeys, using a database of over 500 airports served by UK flights.
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