Smart environments are slowly but surely entering our everyday life. Their design provides many challenges. Not only heterogeneous devices acting and interacting in a dynamic environment but also intentions and activities of humans have to be taken into account. Diverse processes are responsible for achieving unobtrusive and pro-active user assistance. Those can be structured into a pipeline of perception, sensor interpretation, intention analysis, strategy synthesis, and actuation. Along this pipeline we analyze specific possibilities and requirements for modeling and simulation.