This paper tries to draw the large picture of integrating numerical simulation in a multi-disciplinary design process: Starting from a generic model of a technical product, different domain speci?c models will be derived. As practical examples structural analysis as one domain and HVAC (heat, ventilation, air conditioning) as another will be considered. Within these domains different concepts of collaboration support will be discussed. In structural simulation asynchronous collaboration using error and model adaptivity will be investigated. The suggested numerical method is based on high order ?nite elements and on a strictly volume-oriented discretization of solids and thin-walled structures. HVAC simulation, on the other hand, will be integrated into a computational steering environment supporting synchronous collaboration of engineers working at the same time on one common model within their individual virtual reality environment and using online CFD-Simulation.