This category handles conversions from a given quantity of fuel or electricity to kg of CO2.

Mass, volume or energy

You have the option of specifying a quantity of fuel combusted as a mass (e.g. kg or lbs), volume (e.g. litres or gallons) or energy (e.g. kWh or J). All three options might not be available for all fuels (e.g. litres of coal) in which case a zero value will be returned. Such cases can be identified because there will be a zero or missing value for the emission factor in the data table below.

Notice that conversions between mass, volume and energy can lead to errors if you misunderstand the data. This is particularly the case for natural gas. For example, the conversion from mass to volume assumes standard temperature and pressure (STP).

Another potential pitfall is that combustion results in some energy being stored in water vapour. In many cases this energy is lost, but some systems can capture this energy, e.g. a condensing boiler. A conversion factor from volume (or mass) to energy that excludes this energy (i.e. it is inaccessibly stored in water vapour) is called a net calorific value (CV) or low heating value (LHV). The case where it is included is called gross CV or HHV. In the UK, gas consumption quoted in kWh is almost always calculated on a gross CV basis. The difference between gross and net CV is typically no more than 10%.


The electricity item in this category reflects the grid intensity of the United Kingdom by default. If calculations are stored using profiles, the country can, however, be specified within the profile metadata, in which case the appropriate emission factors are taken from the this dataset.


Setting the season parameter to one of spring, summer, autumn or winter, will cause a monthly value to be adjusted according to the factors given in Seasonal_energy_adjustment_factors.

Did you know?