net calorific value (NCV)

The amount of usable heat energy released when a fuel is burned under conditions similar to those in which it is normally used. When fossil fuels are burned, the carbon and hydrogen in these fuels combine with oxygen in the air to produce carbon dioxide and water. Some of the energy released in burning goes into transforming the water into steam and is usually lost. The amount of heat spent in transforming the water into steam is not counted as part of net heat content. Net heat content is also referred to as the lower heating value. Compare gross calorific value.