HOLISTIC OBSERVATIONS ON THE SUSTAINABILITY OF HIGH-RISE BUILDING FACADES

High-rise buildings are currently experiencing a renaissance in Switzerland. The building element with the largest surface area of this omnipresent building type is its envelope, which on average makes up 20-25% of overall construction costs. At that complex interface between the interior and exterior, almost all planning parameters meet with constantly growing demands. Based on 14 current high-rise facades, an interdisciplinary research team from the HSLU T& A [1] developed content-based principles for a decision making instrument [2]. The CTI-Project "Building Envelope" focuses on the following question: Which decisions are made by an investor in early conceptual and planning phases when it orders a sustainable building envelope for a high-rise building, and which effects do those decisions have on the economy, ecology and society? The project generates and communicates knowledge of the highly complex connections and interactions in producing a building envelope for multi-storey buildings. Available analysis data in the system of the EAK/ OAK [3.] allows its direct integration into working tools for the building industry provided by the CRB [4.]. The research project shows the leverage effects of the most important decisions and their effects on the sustainability of high-rise building facades, whereby the insight can also be adapted to conventional building envelopes. The developed matrix presents connections with respect to facade typology, the number of layers of transparent building elements and building utilisation. The relevant systems are assessed and viewed in relation to each other. Firstly, the project demonstrates the considerable influence of early planning decisions such as geometry or the construction using a created economic model. Secondly, a comparison between chosen reference sections shows that the structural details of the building elements and their cybernetic mode of action are decisive for the life-cycle of the building envelope. Buildings only become entirely sustainable with as long of a utilisation period as possible.