The research project analyses theoretically and empirically interactions and effects of complex systems in buildings. Therefore, dependencies of different real estate lots and items are evaluated, interdisciplinary maintenance strategies are developed and – based on a detailed guideline – strategies for a targeting increase of the renewal rate of building shells are demonstrated. Furthermore, the study will evaluate, if – in addition to the functional life of a building – the identity of the building during the whole life cycle and the ability to adapt the layout of a build- ing and the building itself, eg based on a changing environment and usages, will be critical to the lifetime and value of the building.