Energy intensity is usually measured as GDP per unit of energy use, and thus describes how much energy an economy needs to produce economic value. For easier comparison of different countries usually the purchasing power parity GDP per kilogram of oil equivalent of energy use is used.
Energy intensity is a measure of the energy efficiency of a nation's economy. It is calculated as units of energy per unit of GDP. * High energy intensities indicate a high price or cost of converting energy into GDP. * Low energy intensity indicates a lower price or cost of converting energy into GDP. High energy intensity means high industrial output as portion of GDP. Countries with low energy intensity signifies labor intensive economy, Energy Intensity as defined here is not to be confused with Energy Use Intensity (EUI), a measure of building energy use per unit area. For Energy Use Intensity, see the definition on the Energy Star webpage.
Source: Wikipedia - Energy intensity