Heating value is the amount of heat produced by a complete combustion of fuel and it is measured as a unit of energy per unit mass or volume of substance (e.g., kcal/kg, kJ/kg, J/mol and Btu/m³). The heat of combustion of fuels is expressed by the higher and lower heating values (HHV and LHV). The higher heating value is also known as the gross calorific value. The higher heating value (HHV) is measured using a bomb calorimeter; and defined as the amount of heat released when fuel is combusted and the products have returned to a temperature of 25°C. The heat of condensation of the water is included in the total measured heat.

https://en.wiktionary.org/wiki/calorific_value
calorific value ‎(plural calorific values)
The amount of energy produced by the complete combustion of a material or fuel. Measured in units of energy per amount of material, e.g. kJ/kg.
The amount of energy available from an item of food when digested, mostly from carbohydrates and fats

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