Simple Carbon Calculator

Calculate your footprint

This is a free simple calculator designed to enable estimated carbon footprints to be calculated by most UK organisations. If you need a more sophisticated service, or help in setting the boundary or scope of your calculation, we can also offer more comprehensive help and support on a paid-for basis, as described on our Carbon Footprinting Services page.

Help and Advice

We may be able to offer limited help and advice, without charge, if you send an e-mail to calculators@nef.org.uk, but this is limited by staff availability. We can also offer more comprehensive help and support on a paid-for basis, as described on our Carbon Footprinting Services page.

Please don't use this simple calculator for statutory reporting under Climate Change Agreements of the new CRC Energy Efficiency Scheme. A table of factors to apply for the CRC can be found on the Environment Agency's website.

All figures include the incremental emissions due to other GHGs such as CH4 and N2O, so they are compatible with Scope 1 or Scope 2 emissions reporting under the GHG Protocol. They still exclude emissions associated with the production of fuels, such as oil refining or fuel distribution, so are not suitable for use with Scope 3 reporting.

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 2008 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.

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 certified green tariff, but in 2008 Defra decided that green tariffs should be reported using the same factor as for average grid electricity. Although we allow a zero factor for onsite renewables generated, this should only be used if REGOs are not traded. However for the reverse calculation back to energy, we have omitted renewables from the kWh totals. The former marginal factor for electricity and typical CHP purchased values have also now (2010) been removed from the table.

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 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.

How do they compare with household emissions?

Although this calculator was designed for use by small offices, it can easily be used to produce a figure for household emissions. Ignoring transport emissions, the Energy Regulator (Ofgem) suggests that typical annual energy use in a gas heated home is around 16,500kWh for gas and 3,300kWh for electricity. This equates to 4.855tCO2 per annum, but excludes any contribution from oil, LPG or solid fuels. This typical value also excludes the distorting effect of a few very large or badly insulated homes, which increase the average (mean) value.

If you want to compare household usage against the strict average (mean) values, then these are estimated each year by DECC. Recent data (2008) can be summarised as:

The data above is (c) NEF, based on Tables 3.7 and 3.3 of DECC Energy Consumption UK statistics. Conversion factors include CH4 and N2O, and are calculated on a gross calorific value basis. No adjustment is made for LPG in the gas figures; solid fuel conversions are based on domestic house coal.

Where do these figures come from?

All data in this CO2 calculator is based upon the official 2010 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 2010 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 31mpg. If your car fleet returns better figures on average, (or you drive 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. Petrol and diesel emissions are based on UK retail blends, which typically include a small proportion of biofuels.

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. The figures used now are significantly lower than in the earlier years of this calculator due to great fuel efficiency by planes and higher loading factors. Our personal Carbon Workout allows you to estimate emissions from specific journeys, using a database of over 500 airports served by UK flights.

From 2011 we have split out the figures for rail from local buses. Emissions vary greatly depending on time of day (how busy the bus or train is), and location - lightly used rural buses inevitably report higher emissions than ones in central London. Coaches (long distance bus) are generally calculated to have emissions even lower than rail, so are included with trains.

If you are still uncertain about your footprint, or would like to get a more accurate estimate, including advice on how to manage your footprint, then we can also offer more comprehensive help and support on a paid-for basis, as described on our Carbon Footprinting Services page.