Persistence, inertia, adaptation and life cycle: applying urban morphological ideas to conceptualise sustainable city-centre change

Consideration of the speed and scale of change of urban forms has a long history in urban morphological thought. Buildings and forms that persist in the urban landscape through inertia or, more positively, deliberate decisions to retain them create character and ? a more recent argument ? contribute to sustainability not least in their embedded energy. This paper explores issues of the persistence and adaptation of some urban forms, focusing on the central business district of Birmingham, UK. Much of this is now protected as a conservation area, and some of its forms have persisted for centuries. Yet there have been periods of rapid change, and we examine the extent of change following Second World War bomb damage. This allows discussion of the dynamics of change and the agents and agencies responsible for producing new urban forms or retaining existing ones; and this informs exploration of the potential contribution of longevity of form to sustainability. The rapid recycling of some structures, after only a couple of decades, may be very unsustainable ? impracticable and unaffordable ? in an urban context.