The most direct and accurate way to calculate vehicle CO2 emissions is from the fuel used by the vehicles.

Within the monitoring and targeting spreadsheet data is recorded on total annual volumes of fuel used by each vehicle type in the fleet.

This fuel data can be converted in to CO2 emissions as follows:

Annual CO2 emissions= annual fuel volume (litre) x CO2 emissions factor.

Where the emissions factor for the main fuels are:

Diesel          =                       2.63 KG CO2/Litre

Petrol          =                       2.30 KG CO2/Litre

LPG              =                       1.49 KG CO2/Litre

Natural gas  =                     2.65 KG CO2/KG

100% Biodiesel (B100) = 1.07 KG CO2/Litre

Values for all other blends of biodiesel can be calculated by a pro-rata calculation based on the values for "diesel" and "biodiesel (100%)".

E.g. CO2 emissions from 5% biodiesel = (0.05 x 1.07) + (0.95 x 2.63) = 2.55 KG CO2/Litre.