Smoke inhalation is the leading cause of death duringstructural fires. In order to improve life safety during a fire,smoke must be managed and kept away from building occupants.In high-rise buildings, the problem of smoke movementis compounded by a strong stack effect that draws smoke intothe vertical shafts within the building and contaminates thefire-escape stairwells as well as the elevator shafts. If thesmoke can be managed so that the stack effect can be used toadvantage and egress routes can be maintained smoke free,then occupants will have a greater opportunity to avoid theeffects of the smoke generated by the fire.

This paper investigates a smoke control strategy thatinvolves using the elevator shafts as a route of smoke extractioncoupled with pressurizing the stairwells with sufficient freshair to maintain smoke-free conditions in the fire escapes for theentire height of the building. The practicality and efficacy ofthis smoke management strategy is evaluated by employing adifferential-network smoke management computer programthat simulates the paths that smoke will take during a simulatedfire. The computer program is verified by comparing its resultswith a computational fluid dynamics (CFD) software tool,FireDynamics Simulator, for a simple building geometry. Bothprograms compare well when a reasonable set of dischargecoefficients is used to calculate the gas flows through variousopenings in the modeled building. The differential-networkmodel quantifies the paths that the smoke will take and determinesthe smoke properties with a significant reduction ofcomputational time when compared to the time required toprovide the CFD simulations.

Smoke generated by the fire will naturally tend to gravitatetoward the elevator shafts, which exist at the lowest pressurewithin the building. Computer results show that large quantitiesof smoke can be directed away from occupants by controllingand exhausting the smoke through the top vent of theelevator shaft. If exhaust fans are used for smoke venting at thetop of the elevator shafts and pressurization fans are used tomaintain smoke-free conditions in the stairwells, then aprudent fire safety plan will result. The program output is usedto quantify the amount of elevator exhaust and stairwell pressurizationthat is necessary to achieve safe conditions duringthe fire for various building geometries and fire conditions.