The mathematical modeling approach to simulating fire development in a multi-room building complements the experimental approach and/or post-fire on-site investigations. Fire simulation models provide estimates of the amount and temperature of the smoke layer produced, the evolution of toxic gases, and the amount of time available from the onset of fire for the safe departure of occupants. Results can be used to determine the key features of the fire evolution and the corresponding danger to occupants. Studies of this type help to validate or deny the suggested fire scenario and witness statements. Fire modeling thus helps to discriminate between alternative fire scenarios by evaluating the consequences and comparing them with observations.