British thermal unit (UK) (Btu)

The heat energy that can be released by the conversion or use of a particular physical form of energy is expressed in British Thermal Unit (Btu).

The British Thermal Unit (Btu) is the heat energy that can be extracted from other forms of energy such as coal, gas, oil, or electricity. The heat content of combustible energy sources can be expressed either as or as net heat content, depending on whether or not the available heat energy includes the energy to vaporize water.