Architecture, nowadays, is an even more demanding activity in which complexity is the keyword: complex forms, complex functions and complex structures require sophisticated facilities and components, for example, ‘The Cloud’ of D. and M. Fuksas in Rome. These complexities can give rise to numerous risks, among which fire is frequently a central problem. The fire safety norms do not involve an approach integrated with other instruments or building model (BIM), but provide a list of information and constraints. These codes are now shifting away from a prescriptive-based towards a performance-based method due to recent progress in fire safety engineering. Following this approach, a case study simulation of a multi-purpose centre was carried out in Tivoli, near Rome. This simulation allowed greater freedom in architectural composition, a lower risk to people, a larger number of material and building components used and higher safety standards to be achieved. The model is based on the FDS (Fire Dynamics Simulator) language, a simulation code for low-speed flows, focused on smoke, particle and heat transport by fire.