Tricks Of The Trade: High-Rise Building Evacuations
By James C. Elledge, IFMA Fellow, CFM, FMA, RPA, RIAQM
Published in the July 2009 issue of Today's Facility Manager
Q Can you explain why, when a fire alarm goes off in a high-rise building, that the floor with the trouble is the only one (along with those above and below) with an activated alarm? Our school is responsible for five floors of an eight story building, and people are little concerned about being left out when the alarms go off on other floors and not theirs. I have found the code, but there is no explanation.
The Art Institute of Dallas
A The National Fire Protection Association gives this response.
The multiple floors of a high-rise building create the cumulative effect of requiring great numbers of persons to travel great vertical distances on stairs in order to evacuate the building. The process of evacuating some of the largest high-rise buildings in the world may take upwards of two hours.
The fire and life safety systems installed in high-rise buildings today, including automatic fire sprinkler protection, are designed to control a fire and therefore lessen the need to evacuate all occupants. In a typical scenario, the occupants of the fire floor and the floors immediately above and below it should immediately use the exit stairs to descend to a floor level that is at least several floors below the fire floor and await further instruction from safety officials.
Additional explanations are offered here (from pending changes to the 2009 editions of NFPA 1, Uniform Fire Code™, NFPA 101®, Life Safety Code®, and NFPA 5000™, Building Construction and Safety Code):
Evacuation Strategies. One of the NIST recommendations calls for tall buildings to be designed to accommodate timely, full building evacuation when required in specific or large-scale emergencies (widespread power outages, major earthquakes, fires, terrorist attacks, etc.). While NFPA 101 and NFPA 5000 establish minimum criteria for egress to facilitate prompt escape, they also allow for quick relocation of occupants into safe areas (normally the case in healthcare and detention facilities).
As such, total simultaneous evacuation, phased evacuation, partial evacuation, and defend-in-place concepts are currently permitted by the code. Proposed new text provides more detail about various evacuation and defend-in-place concepts addressed by the code and explains why certain strategies are preferred over others in some occupancy types.
In larger buildings, all evacuations—whether partial or total—should be managed to sequence and control the order with which occupants are evacuated and make use of available means of egress. This includes the consideration of the evacuation capabilities and needs of those with disabilities, either permanent or temporary.
According to the U.S. Fire Administration, high-rise structure fires pose a number of challenges both to the occupants and to the fire service. Several of these include:
By nature of their height, smoke movement in high-rise structures is very different from that of other structures. Temperature gradients result in varying pressures throughout the structure, which can allow for the rapid, uncontrolled movement of smoke and flames (known as the “stack effect”).
High-rises often contain multiple types of occupancies, including residential, commercial, restaurant, and underground parking. Each type of occupancy poses a challenge to firefighters and must be approached differently.
By design, exits from high-rise structures are limited. In an emergency, the movement of people out of a building is particularly difficult. In addition, the HVAC and other utilities in some high-rises service multiple levels and can facilitate the spread of smoke and flames through a building.
High-rise structure fires require significantly more personnel and equipment to extinguish than do other types of fires. These fires further strain the responding fire department and firefighters and are inherently more difficult for the fire service to handle.
Findings. Each year, an estimated 15,500 high-rise structure fires cause 60 civilian deaths, 930 injuries, and $252 million in property loss. High-rise fires are more injurious and cause more damage than all structure fires.
Three-quarters of high-rise fires are in residential structures, but these cause only 25% of dollar loss.
The leading cause of all high-rise fires is cooking (38%), but cause patterns vary by specific property type. Sixty-nine percent of high-rise structure fires originate on the fourth floor or below; 60% occur in apartment buildings; and 43% originate in the kitchen.
Elledge,facility/office services manager for Dallas, TX-based Summit AllianceCompanies, is the recipient of the Distinguished Author Award from theInternational Facility Management Association (IFMA), is an IFMA Fellow, and isa member of TFM’sEditorial Advisory Board. All questions have been submitted via the “Ask TheExpert” portion of the magazine’s Web site. To pose a question, visit this link.
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