Skip to main content

Heavy duty vehicle, greenhouse gas and kWh calculations

This is a standardised approach to estimating heavy-duty vehicle (HDV) fleet CO2e emissions. HDV fleets usually maintain complete and accurate records of both fuel consumption and mileage, which is typically recorded in kilometres.

The methods are presented in order of accuracy. You should use the most accurate methodology available for each vehicle in your fleet.

Method one: fuel consumption data

If you have comprehensive fuel consumption data from fuel card records and/or a bunkered fuel system, you should calculate greenhouse gas (GHG) emissions and energy use by applying the factors in the table below to the quantity of fuel consumed.

The diesel and petrol factors are based on the biofuel blends sold in the UK.

Table 8 – Emission factors for different type of fuel

FuelUnitsGHG Scopekg CO2e/unitkg CO2e/kWhkWh/unit
PetrolLitres12.100.229.545455
DieselLitres12.510.2410.45833
CNGkg12.56250.1814.23611
LNGkg12.58190.1814.34389
LPGlitres11.560.217.428571
ElectricitykWh20.2120.191.0000
Electricity T&DkWh30.0170.021.0000

Methods two to five: mileage data but no fuel data

If fuel consumption data is unavailable, you should calculate emissions based on the distance travelled (miles or kilometres) and the appropriate conversion factor. The conversion factor used will depend on the additional vehicle information available (see table below).

Table 9 – Overview of HDV GHG methodologies two to five

GHG MethodologyMileageArtic/rigidGVWLoad Factor
Method two✔️✔️✔️✔️
Method three✔️✔️✔️
Method four✔️✔️
Method five✔️

To convert from kgCO2e/km to kWh/km, divide the GHG factor by the fuel factor (diesel) expressed in kgCO2e/kWh. This will give the energy consumption in kWh/km.

Average HDV GHG emissions are:

  • Average HDV GHG emissions, any type (non-refrigerated): 0.8720 kgCO2e/km.
  • Average HDV GHG emissions, any type (refrigerated): 1.0088 kgCO2e/km.

Table 10 - Rigid HDV average GHG emissions (not refrigerated)

GVW ClassGVW% Load factorkg CO2e km-1
Class 1> 3.5-7.5t0%0.4522
50%0.4910
100%0.5299
UK Average 46%0.4856
Class 2>7.5-17t0%0.5408
50%0.6172
100%0.6935
Class 3>17t0%0.7468
50%0.9083
100%1.0699
UK Average 54%0.9743
AverageUnknownUK Average 53%0.8231

Table 11 - Rigid HDV average GHG emissions (refrigerated)

GVW ClassGVW% Load factorkg CO2e km-1
Class 1> 3.5-7.5t0%0.5384
50%0.5847
100%0.6311
UK Average 46%0.5783
Class 2>7.5-17t0%0.6439
50%0.7350
100%0.8261
UK Average 39%0.7059
Class 3>17t0%0.8888
50%1.081
100%1.274
UK Average 54%1.1603

Table 12 - Articulated HDV average GHG emissions (not refrigerated)

GVW ClassGVW% Load factorkg CO2e km-1
Class 1> 3.5-33t0%0.6156
50%0.7664
100%0.9173
UK Average 44%0.7664
Class 2>33t0%0.6325
50%0.8384
100%1.0444
UK Average 62%0.9126
AverageUnknownUK Average 61%0.9126

Table 13 - Articulated HDV average GHG emissions (refrigerated)

GVW ClassGVW% Load factorkg CO2e km-1
Class 1> 3.5-33t0%0.7118
50%0.8867
100%1.0616
UK Average 44%0.8867
Class 2>33t0%0.7310
50%0.9698
100%1.2087
UK Average 62%1.0558

Many organisations purchase grid electricity from renewable sources backed by Renewable Energy Guarantees of Origin (REGO) certificates, or grid biomethane backed by Renewable Transport Fuel Obligation (RTFO) certificates.

You can report the greenhouse gas (GHG) emissions associated with this electricity or gas using the supplier’s market-based emission factor. For example, 100% renewable electricity may be reported as 0gCO2e/kWh. This should be reported alongside the location-based national grid emission factor.

This is because the emissions benefit of renewable electricity or gas has already been accounted for within the overall UK grid emissions figure. The benefit can only be claimed once. This also applies where the carbon factors for other consumers have been adjusted upwards to compensate.

The requirement to do this is fully documented in:

  • HM Government: environmental reporting guidelines: including streamlined energy and carbon reporting guidance. March 2019, pages 49-57.  

    Where organisations have entered into contractual arrangements for renewable electricity, such as through power purchase agreements or the separate purchase of renewable energy guarantees of origin, or consumed renewable heat or transport certified through a UK Government scheme and a want to reflect a reduced emission figure based on its purchase. In this case you can show the relevant report using a ‘market-based’ reporting approach. You can show this as well as the ‘location-based’ grid-average figures. It’s also worth specifying whether the renewable energy you use is additional, subsidised and supplied directly, including on-site generation, or through a third party. A similar ‘dual reporting’ approach should be taken for biogas and biomethane (including ‘green gas’).

  • GHG protocol, scope 2 guidance, corporate standard, section 1.5.1, page 8  

    Text: “If your company has different operations in markets which provide products or supplier-specific data in the form of contractual instruments, you should report scope 2 emissions in two ways and label each result according to the method: one based on the location-based method, and one based on the market-based approach. Using this method is also called ‘dual reporting’.” 

  • Time specific emission factors are permitted. The HM Government environmental guidelines for reporting state:   

    Where available, time specific (hour by hour) grid average emission factors should be used in order to accurately reflect the timing of consumption and the carbon intensity of the grid.

    The carbon intensity of the grid varies throughout the day and year. The grid data is publicly available in half hourly intervals. However, organisations may find it difficult to provide half hourly consumption data unless they are billed in this way.   

    If your company generates renewables on-site or locally, your company is known as a zero or low carbon supply organisation.  

    For example, it may do this by using photovoltaics or wind with a localised electricity grid.

Previous section
1.3. Car and van greenhouse gas and kWh calculations
Next section
2.0. Rationalise your fleet