Reconstitution of the dynamics of an urban building stock

What are the patterns and influences on the lifespan of the building stock? This paper presents (1) the reconstitution of an urban building stock composed of more than 60000 buildings, (2) the analysis of the development of this stock over a period of 180 years (constructions and demolitions), and (3) the analysis of building mortality patterns and reasons for demolition resulting from historic decisions and regimes. A method to reconstitute the stock from different data sources is presented. The mortality models take into account not only the present demolition rates and the age distribution of the survivors'but also the disappeared buildings. The main results are new insights into the lifespan behaviour of buildings according to their period of construction (cohorts) as well as the reasons for demolition. The demolitions do not show specific explanation patterns, but changing influences of the construction activities over time. The average demolition age of all buildings in Zurich, Switzerland, decreased from over 200 years to fewer than 70 years. A total of 18000 buildings have been demolished over the 180-year period. The presented methods and results can be integrated in multidimensional geographical information systems (GIS) as comprehensive planning, scenario and regulatory tools.