The possibilities of computer simulation also extend to issues inadequately covered by normative analysis and in particular to dynamic aspects of design such as human movement and circulation. The paper reports on a framework for addressing two related problems, (a) the simulation of fire escape from buildings and (b) the simulation of human movement on stairs. In both cases we propose that current evaluation techniques and the underlying design norms are too abstract to offer a measure of design success, as testified by the number of fatal accidents in fires and on stairs. In addition, fire escape and stair climbing are characterized by great variability with respect to both the form of the possible designs and the profiles of potential users. This suggests that testing prototypical forms by typical users and publishing the results as new, improved norms is not a realistic proposition for ensuring a global solution. Instead, we should test every design individually, within its own context. The development of an affordable, readily available system for the analysis and evaluation of aspects such as fire escape and stair safety can be based on the combination of the technologies of virtual reality and motion capture. Testing of a design by a number of test people in an immersion space provides not only intuitive evaluations by actual users but also quantitative data on the cognitive and proprioceptive behaviour of the test people. These data can be compiled into profiles of virtual humans for further testing of the same or related designs.