Computer programs are valuable tools that can guide the design of any fire safety plan, particularly in high-rise buildings that present many demanding design and smoke management challenges. A software package is used to examine the possibility of employing air-handling units to pressurize fire escape stairwells in order to maintain a smoke-free environment throughout the fire. The computer results suggest that equipment with modest capacity can achieve that goal, and the opportunity for success is increased when the stair shaft is constructed with airtight materials and all openings in the shaft are tightly sealed.

The program output is used as a guide for the selection of air-handling equipment that has sufficient capacity to keep smoke from invading the stairwells. As the door at the fire floor is opened, the capacity of the positive pressure fans must be increased to prevent smoke from entering the stair shaft. Pressurizing stairwells must always balance the benefits of providing fresh air in the fire escapes with the disadvantages of creating a situation that makes it difficult to open a fire escape door against the increased pressure inside the stairwell.