A method and computer-readable medium for modeling smoke propagation in a structure are presented, along with applications of the method. A model is provided of a multiplicity of compartments within the structure, and the presence of a fire within a compartment is determined. The energy and smoke released by the fire is estimated, and smoke flows out of the compartment are determined. Each compartment having a smoke source is analyzed, individually, for the propagation of smoke. Each compartment is assumed to have a homogenous upper smoke layer and a lower cool air layer. The analysis includes a mass and energy balance to determine the change in characteristics of the upper smoke layer, where a known pressure for the lower cool air layer is used for the balance. For multiple smoke sources into a compartment, the contributions to the mass and energy balance of each smoke source are considered additive.