Intelligent Building Envelopes - Fad or Future?

The annual solar energy received at the envelope surfaces of a building is in the same order as the energy needed for operating the building, even at high latitudes. With better utilisation of this energy, one should potentially be able to create buildings that are self-sufficient with energy. Much interest has recently been focussed on intelligent facades or intelligent envelopes, that by adaptive or responsive actions will make it possible to utilise more of this energy for building purposes, such as heating, cooling, ventilation, lighting and electricity supply .One example of such an intelligent building envelope is a double façade which incorporates natural ventilation systems. The term intelligent is, however, often used without any really deep understanding of the complexity required beyond common descriptions such as interactive, adaptive and responsive. It is easily understood that an intelligent envelope system must be dynamic, i.e. able to change its main functional parameters according to the dynamic demands of the changing situations. But in order to be truly intelligent, the system must also be able to learn from earlier experience and use this knowledge to cope with new situations. This paper summarizes research work within several areas related to the development of intelligent building envelopes. The intelligence concept as related to buildings has been studied in detailed, and applied to daylighting by specifying how the envelope should create optimal daylight conditions indoors, based on input from the external conditions and occupant preferences. Occupant responses to double envelope facades have been surveyed in two buildings in Norway, one with a simplified ventilation system incorporated in the facade, one with an integrated PV system. System analysis has been performed for high latitude climates to dev