The construction, use and end of life of buildings have great environmental impact. It is believed that:

• Construction accounts for 40% - 3 billion tons - of the total flow of raw materials (primarily stone, gravel, sand, clay, iron ore and other quarried products) into the global economy every year.
• The construction and the operation of buildings worldwide also accounts for 25% of all virgin wood use, 40% of total energy use, 16% of total water withdrawals and generates enormous quantities of solid waste.

It is therefore crucial to build environment into the design stage of buildings. One reason is that it is usually cheaper to take measures at this stage than to retrofit them after construction. Another is that architects, building service engineers and other specifiers don't always put environment first. A HEEPI laboratory benchmarking exercise found, for example, that newer buildings often had worse energy consumption than older ones, partly for this reason. Fortunately, there are now several techniques for assessing a building's environmental performance (see Best Practice section).

The energy and water sections also show that there is much which can be done to reduce energy and water consumption within existing buildings.