Fire Safety Engineering: The Computational Simulation of the Escape in a Historic Building in Bologna

In the field of Fire Safety Engineering (FSE), virtual reality has increasingly assumed an important role, especially for the simulation of fire and escape. The present work aims at comparing the potential of virtual simulations of the escape of occupants in case of emergency to simulations based on traditional calculations. Above all, the goal is to highlight the greater adherence to reality of the simulations that use behavioural models compared to those that use hydraulic models. Simulations are performed for the case study of a listed historic tower in Bologna city centre and calculate the Required Safe Escape Time (RSET) in various evacuation scenarios using the innovative Pathfinder® software which, in addition to using flow-based models, is "agent-based", as it manages the variables related to behavioural factors and can model complex escape scenarios faster than hand-made calculation. Case study results show that RSET times calculated with the behavioural steering mode in the virtual environment are 15-19% higher than the hydraulic mode (SFPE) and therefore demonstrate that the Steering mode is more realistic, as human behaviour significantly influences the evacuation process. Anyway, all the realistic simulations return safety margin times above 100% of the RSET as asked by national law, highlighting that it is possible to guarantee the safety of the occupants in a particular historical building using innovative Fire Safety Engineering (FSE) approaches, even if the prescriptive rules are not respected.