In his book How Buildings Learn, the author Stewart Brand outlines the process whereby buildings evolve over time to meet the changing needs of their occupants. He describes each building as consisting of six layers, each of which functions on a different timescale. These range from the site itself which has a life cycle measured in centuries, through to the building (decades), interior fit out (years), technology (months), to stuff (days). The effectiveness of a design will depend on how well it resolves the tensions that exist between these layers of the building. The principles behind this complex situation have been known to us for a long time, at least since the 1970s when Frank Duffy first introduced the world to his ideas about the physical and temporal layers of the building – in his terminology the ‘shell, services, scenery and sets’ which anticipates Stewart Brand’s own take on the interplay of building layers.
