View the common conversion factors for energy use in Ireland.

Energy units

Energy is delivered in many different fuels and sources and can be expressed in terms of volume, mass, energy or emissions. Using the below conversion factors, it is possible to express each fuel or energy source in common units of energy or emissions so that they can be compared and aggregated.

Energy unit types

  • Joule(J): Joule is the international unit of energy
  • Kilowatt hour (kWh): This is the conventional unit of energy that electricity is measured by and charged for commercially.
  • Tonne of oil equivalent (toe): This is the conventional standardised unit of energy and is defined on the basis of a tonne of oil having a net calorific value of 41,868 kj/kg. A related unit is the kilogram of oil equivalent (kgoe), where 1 kgoe=103 toe.

Energy conversion factors

From Multiply by    
toe 1 11.63 41.868
MWh 0.086 1 3.6
GJ 0.02388 0.2778 1

Calorific values

The conversion of a fuel quantity from physical units into energy units requires a conversion factor which expresses the heat obtained from one unit of the fuel. This conversion factor is termed the calorific value or heating value of the fuel.

FuelNet Calorific Value toe/tNet Calorific Value MJ/t
Crude Oil 1.0226 42,814
Gasoline (Petrol) 1.0650 44,589
Kerosene 1.0556 44,196
Jet Kerosene 1.0533 44,100
Gasoil / Diesel 1.0344 43,308
Residual Fuel Oil (heavy oil) 0.9849 41,236
Milled Peat 0.1860 7,787
Sod Peat 0.3130 13,105
Peat Briquettes 0.4430 18,548
Coal 0.6650 27,842
Liquefied Petroleum Gas (LPG) 1.1263 47,156
Petroleum Coke 0.7663 32,084
  Conversion Factor Conversion Factor
Electricity 86 toe/GWh 3.6 TJ/GWh

Emission factors

The table below shows emission factors for CO2 per unit of energy for specific fuels.

Fuel tCO₂/TJ (NCV) g CO₂/kWh (NCV)
Liquid Fuels    
Motor Spirit (Gasoline) 70.0 251.9
Jet Kerosene 71.4 257.0
Other Kerosene 71.4 257.0
Gas / Diesel / Oil 73.3 263.9
Residual Oil 76.0 273.6
LPG 63.7 229.3
Naphta 73.3 264.0
Petroleum Coke 92.9 334.5
Solid Fuels and Derivatives    
Coal 94.6 340.6
Milled Peat 116.7 420.0
Sod Peat 104.0 374.4
Peat Briquettes 98.9 355.9
Natural Gas 56.9 204.7
Electricity (2017) 121.3 436.6

Fuel densities

Conversion from volume (litres) to mass (tonnes) for liquid fuels requires the densities of the liquids, with the most common fuels shown here.

FuelDensity (in litres/tonnes)
Kerosene 1250
Crude Oil 1067
Gasoline (Petrol) 1325
Diesel / Gasoil 1183
Heavy Fuel Oil 1062
LPG* 1915
Biodiesel 1136
Bioethanol 1250
Pure Plant Oil 1087
*Assumes a mixture of 70% propane & 30% butane by mass  

Primary energy conversion factors

Energy consumption can be expressed as total final consumption (TFC) or total primary energy requirement (TPER). TPER accounts for the energy that is consumed and/or lost in transformation, transmission and distribution processes. It is calculated by applying conversion factors, which vary by fuel type, to TFC values. The table below shows the conversion factors for 2018. Historic conversion factors can be downloaded here.

Fuel2018 conversion factor
Aviation fuels 1.1
Biogas / landfill gas 1.0
Coal 1.1
District heat 1.1
Electricity 1.962933
Gasoil 1.1
Kerosene 1.1
Light, medium & heavy fuel oils 1.1
LPG 1.1
Manufactured Ovoids 1.2
Marked diesel, road diesel & petrol 1.1
Natural gas


Peat 1.1
Pure biodiesel / bioethanol 1.1
Solar thermal 1.0
Wood briquettes / chips / logs / pellets 1.1