Energy efficiency improvements like better building envelopes (e.g. insulation, air sealing and better windows) can reduce overall building energy use and building energy use per floor area. At the same time, non-efficiency factors can also affect building energy use per floor area. For example, in the residential sub-sector, the addition of larger living spaces (greater floor area per person) can also reduce the building energy use per floor area, since some components of energy use in homes do not grow in proportion to floor area (e.g. water heating, cooking and refrigeration).
Total building energy use per capita (see the table below) declined in more than half of the major world economies, mostly in wealthier countries that started from a very high level of energy use per capita.
Total building energy use for the world in 2000-2012 grew up by about 18%, from 102 EJ to 120 EJ, and represents over 30% of total final energy consumption for all sectors of the economy. Total world's building floor has increased during the same period of time by 43.5%, from 142 billion m2 to 204 billion m2. World's population grew up by 15.5% from 6.1 billion in 2000 to 7.0 billion in 2012.
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