During early-stage planning, numerous design decisions are taken in an argumentative manner, based on occupation with the building site according to the different infl uencing aspects (e.g. topology, wind, visibility, circulation, activities etc.). In this context, sketches, diagrams and spreadsheets are the workhorses for elaboration. However, some of these phenomena are dynamic by nature, and are rather poorly modeled when utilizing static media. In our work, we thus show how agent-based simulation can be used to compute and visualize dynamic factors, in order to inform the decision process on a qualitative level. As a matter of fact, simulations may be used as a design tool in their own right, for analysis and objectifi ed comparison among multiple design variations.