Energy Intensity is the amount of energy consumed per unit of output. It can be applied at the level of a machine, a production line, a factory or a process plant. It is also used by governments and industry bodies to characterize whole country economies and industry sectors. Industry sectors where energy costs are a significant part of total costs are called ‘energy intensive’ sectors – for example, manufacture of cement, chemicals (including petrochemicals), primary metals and paper. Companies in energy intensive sectors almost always use energy intensity as a key performance indicator.