In Germany (as indeed in most other industrial nations today), the construction and operation of buildings account for the consumption of a major segment of national resources as well as for 56 per cent of the overall volume of waste matter (figure for 2005). In view of the ever diminishing quantity of raw materials available, therefore, the building sector bears a special responsibility for increased efficiency in their use. In recent years, legislation has successively reduced the volume of products used and the environmental effects of construction and refurbishment. Attention also has to be focused on the operation of buildings: while the erection and disposal of even new housing over a period of 50 years means a consumption of raw materials of about 30 per cent, the actual operation of the buildings accounts for roughly 70 per cent.