Since the advent of motion pictures, suspenseful building evacuations have been a common scene in action films. In real life, however, building evacuations are usually sober events, with evacuees marching down vertical exit enclosures to access building exits. Even so, vertical exit enclosures are not the only option for evacuation of multi story buildings. Below, we look at four alternative means of evacuation for multi level buildings, listing the advantages and disadvantages of each option.
What sounds like a strategy from James Bond is actually proposed by some building developers, who recommend having one or more helicopters stationed on a building’s rooftop to save evacuees who reside there to escape smoke and flames.
The advantages of helicopter evacuation are two: it could evacuate building occupants in the event that exits for evacuation are inaccessible, and it could reduce the number of evacuees that use vertical exit enclosures, thus reducing the likelihood of egress jams. Its disadvantages, of course, are that helicopters are expensive to buy and maintain, and they could only transport a small number of building occupants with each flight.
Commonly used in Asia, flexible evacuation chutes come in two varieties: chutes that angle away from a building and allow evacuees to slide toward the ground, and collapsing chutes that run vertically, growing progressively narrower to slow evacuees’ descent.
The advantage of flexible shoots is their ability to serve as emergency exits for evacuation when normal exits are inaccessible. Their disadvantage is they require a certain amount of deployment space that may be unavailable. However, some collapsing chutes can be used in building shafts.
Depending on their size and weight capacity, powered platforms can move a significant number of evacuees to ground level in a few minutes. And they are usually considered more reliable than elevator systems.
The advantages of powered platforms are their potential ability to transport large numbers of evacuees, and their ability to transport evacuees who can’t use stairs. Their disadvantages are their reliance on electricity, which could render them useless if utility power and generator power are unavailable, and the expensive construction work required to implement them in existing buildings.
Since 1997, elevators have been approved as a means of egress, as long as they meet certain conditions set forth in the Life Safety Code. Furthermore, they are also used as a means of egress under fire department or emergency responder supervision.
When they meet the conditions set forth in the Life Safety Code, the advantages of elevators as a means of egress are their ability to transport evacuees who cannot use stairs, and their ability to be used in certain emergency situations that would not disrupt their function. Their disadvantage is that the heat generated by intense fires can still cause them to malfunction.
The permanence of stairwell exits for evacuation
The means of evacuation listed above are not intended to replace vertical exit enclosures. Rather, they are proposed to lighten egress traffic in the enclosures, assist certain types of evacuees, and provide evacuation opportunities when evacuation via exit enclosure is not an option.
Most alternative evacuation options possess merit. But the best ways to improve evacuation safety are ensuring that vertical exit enclosures and exit discharges meet OSHA regulations, and ensuring they are outfitted with luminescent striping and signage in accordance with the International Building Code (IBC) and International Fire Code (IFC). At Jessup Manufacturing, we specialize in luminescent safety products for all building areas, including vertical exit enclosures.