Despite the increasing interest in the functionality and humanization of architecture, there are few studies covering the occupation of buildings and methods to represent activities in spaces. This article explores new software for simulating and virtual modelling in order to facilitate the analysis and visualization of events in buildings. Of particular importance is programming the behaviour of 3D-characters according to the probabilistic evolution of activities, and producing animations and interactive models. This approach was tested in a study of three emergency units of hospitals in Chile. Although a full integration of software was not possible, the process developed (in particular the subjective tours) demonstrated that the technique can provide new information about the functioning and spatiality of the units. In addition, it suggested operative and architectural improvements supporting the management and design of facilities.