Parametric skin is an experimental setup to design parametric driven facades on an existing building situated in the city of stuttgart. It´s a mixed used building with shops offices and apartments surrounded by schloßpark, a five star hotel,fashion shops, the main central station and one of the most important main street which connects the inner city to the suburb.As reaction to the local conditions, internal and external criteria the facade materializes as a skin for the building.Each element was first drafted in the parametric modeler Generative Components and tested for it´s performance. After the first component was set up, a parametric program was written in python to interact with the modeler maya. This program gives you the possibility to populate components designed in maya on any given surface and use external data, parameters for parametric transformations. The final form of the elements is controlled by several external parameters like sun-position and shadows derived from Autodesk Ecotect and internal parameters like program and transparency. These parameters are transformed into excel sheets or bitmaps, which later are used to inform these elements. Later on, the influence of each parameter was adapted to the special needs of parts of the facade e.g. store window: less shading device, more transparency. This gives you the possibility to react even more sensitive to the given parameters, which otherwise would be too rigid or even fixed.