Understanding obsolescence:

What is obsolescence? Numerous older buildings have been demolished due to being labelled as obsolete. There is a general understanding that buildings, similar to machinery and durable consumer goods, should be demolished and replaced when they become obsolete. The truth of this assertion is examined and found problematic, as obsolescence is not clearly understood in conceptual or practical terms. Obsolescence presents a serious threat to built property as it rarely accounts for the immobile, long lasting and (financial and natural resource) capital-intensive characteristics of property, nor its societal and cultural significance. Minimizing obsolescence and extending longevity are therefore indispensable for maintaining the physical, economical and societal investments. The characteristics and symptoms of obsolescence are explored specifically to address how can buildings be diagnosed and when and to what extent is demolition an unavoidable consequence. A theoretical/conceptual model is developed which allows for different kinds of obsolescence to be characterised and distinguished. The model distinguishes between physical and behavioural factors and between endogenous and exogenous factors. It also accounts for the often inverse relation between the increase of complexity of types of obsolescence and the decrease of the owner's possibilities to manage it. Through the provision of an interrelational approach, the model explains why obsolescence occurs and it can be used as a basis for structuring an evidence-base on obsolescence