Like the skin a living creature, the envelope is the primary actor in the complex process of maintaining homeostasis in the building. In human life, however, the closed circle of homeostatis is opened up by psychological, political, social and cultural surpluses. The facade of a building functions not only on a purely biological level. It assembles the building’s interior, which it protects, and the external public realm with which it communicates. The surface of the building has a double existence intervening in two disparate worlds: the private inside and public outside, although this identity is not radically changed by contemporary technologies. It is a boundary which does not merely register the pressure of the interior, but resists it, transforming its energy into something else. The envelope is the result of an act of violence on both spheres.
In the same way that artificial intelligence and genetic modification have become key political subjects, the building envelope is central to a political discussion of material practices. Energy and security concerns have replaced circulation and flow as the subjects of contemporary architecture.