Urban environmental efficiency relates to how well the built environment encourages the efficient use of natural resources—in particular, land, energy and water—and the implications of the built environment for waste production and minimisation.
Only limited data exist on the extent of land used by the built environment. The available data show that the built environment occupies only a small proportion of Australia. According to the Australian Collaborative Land Use Mapping Program, 14 031 square kilometres (0.18% of Australia's total area) were devoted to 'urban intensive uses'.31 There are currently no formal methods to detect and report land-use change nationally in Australia. However, it is clear that urban areas in Australia are continuing to grow in size. Land that is taken over for urban development is land that cannot be used for other purposes, and often this land has high environmental value.
In 2008-09, Australian households used 998 petajoules of energy—about 12% of Australia's total national energy use.32 About three-quarters (74%) of household energy is obtained from secondary sources such as electricity and refined products, with the remaining quarter obtained from primary sources such as natural gas and LPG (liquefied petroleum gas). There has been a trend towards increasing use of primary sources, mainly reflecting growth in household use of natural gas and LPG. Use of solar energy as a primary energy source by households is rather small, at 3.1% in 2008-09 (up from 1.6% in 2001-02).
Household energy use per person increased in the first part of the decade, peaking at 48.0 gigajoules per person in 2005-06. Since then, household energy use per person has fallen by about 5% to 45.5 gigajoules, reflecting more efficient use of energy (Figure 10.13).