Sustainable architecture should represent a holistic approach, both ecological and economical, but also sustainable in the social and cultural fields, and, most importantly, able to fulfil the aesthetic expectations of the society. It should be concerned with far more than just technical and technological aspects of the construction. Assuming that form is the outer expression of a building’s aesthetics and form, in turn, is represented by the building skin, or envelope, we can argue that such “envelope” does not only have to define the appearance of the building we perceive, it can, in the way it is designed, shaped and related to the many functions a building has, also have the potential to solve its future technical needs. Can sustainable architecture have its own form and aesthetics; is any particular formal expression advantageous for sustainable architecture? Is there anything like "intelligent skin"? Can the envelope of a building carry more functions and become separated from the building itself? Is the concept of a "house inside a house" the solution to future building needs of all scales and typologies?