Building Exit Strategy

Emergencies in high-rise buildings can arise from				communications to occupants, better occupant
numerous factors including man-made,				preparedness for evacuation during emergencies,
weather-related, building system failure, and				and incorporation of appropriate egress
terrorist acts. In these emergencies, the presence				technologies, which may allow all occupants an
of sprinklers will not control the emergency.				equal opportunity for evacuation and facilitate
These emergencies might require a total or partial				emergency response access.
building evacuation. But when a tall building has				A new proposal addressing supplemental
over fifties occupied floors; many questions and				evacuation equipment has been introduced for the
concerns have been raised regarding the difficulty				2009 editions to NFPA code changes for high-rise
of evacuating hundreds or even thousands of				buildings. It is intended to provide guidance to
people and their safety. This article summarizes				building owners and others considering the
the importance of building exit strategy to ensure				voluntary use of such systems and equipment for
that everyone would have the equal opportunity				exit strategy. If provided, the evacuation
to get out in the event of an emergency that				equipment is intended to serve in a supplemental
requires total building evacuation.				capacity and will not satisfy any code
Building Evacuation				requirements pertaining to means of egress. While
If there is an evacuation called for, it is the				the proposal is not specific to high-rise buildings, it
stairways that will be used by all occupants. Unless				is expected that such evacuation equipment
damaged by fire or made untenable due to				would be considered for tall buildings.
smoke or fire, the interior stairways provide the				To comply with these recommendations, tall
most stable and least threatening path to the				buildings would need to incorporate life safety
outside and safety. Mobile occupants who are not				features that are beyond the code-required
incapacitated by the fire can safely walk to				minimum to assist the building staff in
safety using the interior stairs with little assistance				implementing the appropriate crisis response
from fire fighters. Immobile or incapacitated				evacuation plans that address the life threatening
victims will require assistance in using the stairs				conditions of a tall building emergency to protect
and may need to be carried out of the building.				both the building occupants and firefighters.
In extreme emergencies, everyone would have				Fire Escape Chute - An Alternative Means Of
to get out quick and the whole building would need				Escape
to be emptied in the shortest possible time. But				There was a program on Discovery Channel
when a tall building has over fifties occupied floors;				named 'Beyond 2000' (out of Brisbane Australia),
the sheer numbers of people make evacuation				showed how hospital staff ran a drill wherein they
difficult as it takes more time for occupants to				evacuated bed-ridden patients from upper floors
evacuate by using the stairs. Hence it is				via what appeared to be a long stocking,
imperative that adequate egress capacity and exit				suspended outside the building from a dedicated
strategy must be available for any emergency,				window/door. This long stocking is a "life saver"
not just fire. Building size, population, function, and				device commonly known as fire escape chute.
iconic status should be taken into account in				This escape chute can be installed in the tower
designing the egress system.				from window, rooftop, served as lifeboat to
Historically the used of elevators by occupants as				increase egress capacity; in dedicated
a means of escape under fire conditions are				fire-hardened shafts, so that everyone could
considered to be hazardous and should be				escape within an hour - an advantage for disabled
avoided. However with "mega" high-rise buildings				people to escape on their own. For controlling the
now exceeding 400 meters (1,312 ft) in height, full				descent down the chute - user merely stick out
evacuation for thousands of people utilizing stairs				their elbows/knees. They're typically made of
alone would appear to be problematic, especially if				Outer layer: 100 % fiber glass fabric (flame
the needs of the mobility challenged are taken				resistant); Middle layer: modacryl / elastomer;
into account. Some fire safety professionals				(restraint / control the speed of descent); Inner
believed if an elevator is remote and separated				layer: aramid / rhovyl (supports the whole weight
from the fire area with an auxiliary power supply,				of the chute).
it could be used for rescue purposes under the				Escape chutes are not required by any of today's
fire department's control, especially to evacuate				building or fire codes, making their use voluntary
immobile occupants.				and at the discretion of building owners. However,
Most buildings are not equipped with fire escape				there is an increase in the use of escape chute at
for alternative means of egress. People are				buildings and high-hazard industrial world wide.
entrapped in blazing tall buildings if the main egress				They are recognised by many fire authorities as a
path is cut off and they are beyond the reach of				hardware solution to correct egress deficiencies
the fire department's aerial devices. In such				and to increase egress capacity in old buildings
extreme situations and if the conditions permit,				where it is not possible to provide exterior fire
the only rescue option left is to use helicopter to				escapes or increase the size of existing stairways
airlift people from the roof. However, this is a				in its structure.
very dangerous attempt and the least preference				Think about it. If fire escape chutes is available in
tactic. The rising smoke and the intense heat				multi-story buildings as an alternative means of
from the fire could cause the rotor of the				escape, it can provide a relatively safe means of
helicopter to explode.				egress for many people. Given the opinion that
Lessons Learned From WTC Evacuations				elevators/lifts are unsafe for fire egress, stair
There are lessons to be learned from any				travel is taxing and potentially dangerous for the
disaster. The World Trade Centre tragedy				aged and the physically impaired, evacuation via
demonstrated the particular vulnerability of				escape chutes provides a means of egress
high-rise buildings during an emergency evacuation.				available to all people.
In 1993 a massive bomb was planted in the				Building occupants are generally familiar with the
parking garage of the World Trade Center. Medias				location of the fire escape chutes. Fire fighters
reported that there were no emergency lights				should expect to find occupants attempting to
according to survivors. Some people, including a				use the fire escape chutes when the stairways
pregnant woman, were evacuated via rooftop				are untenable. And, even though for many
helicopter landings. Most, if not all, of these people				occupants the fire escape chutes is a more
emerged with their faces blackened with soot				threatening egress path, these same occupants
from the thick, acrid smoke in the darkened fire				may use the fire escape chutes as their first
stairs.				preference due to proximity even if the
One occupant, so the story goes, was				stairways are clear of smoke, especially for the
wheelchair-bound and couldn't navigate the stairs.				mobility impaired.
People are always told NOT to use elevators in a				Fire escape chutes would also make the
fire, so he couldn't go that route either. Rather				firefighters' job a whole lot easier and safer.
than leave their friend to his death - two other				Instead of leading/carrying people down several
occupants hand-carried him 51 flights down to the				floors in high-rise buildings and simultaneously
street - with one of the carriers suffering a heart				fighting a fire - people could escape on their own -
attack.				freeing firefighters to fight the fires.
Apparently it took a full seven hours to evacuate				In fact, because people could get out on their
all the occupants. This was unacceptable to most				own - the firefighters, would have exclusive
people - especially those who occupied the				access to the fire stairs to get up and a rapid
towers.				avenue to escape to the street should they need
Following the terrorist attacks on the World Trade				it. How many times have firefighters rank and file
Centre on 11 September 2001 where many of its				needed climbing ropes and gear to rappel down
occupants had no time to escape before the				the outside of buildings because those buildings
towers collapsed, the National Institute of				were no longer structurally sound?
Standard and Technology (NIST) estimate of how				Carrying some 100lbs of gear up the stairs means
many people might have died if the building had				firefighters have to carry it down again as well.
been fully occupied when the planes struck at the				How much bottled air can they carry (in their
WTC: 14,000 rather than 2,749 - that should be a				self-contained breathing apparatus) to sustain
cause for everyone to recognise the value in				them both up and down? Firefighters do have a
improving the odds of surviving a major fire in a				better chance of surviving if they could merely
high rise building, regardless the cause.				jump into a chute to escape rather than feel their
With egress access identified as an impediment to				way down smoke-choked fire stairs.
speedy evacuations, stakeholders must anticipate				Conclusion
the need to rapidly escape; plan primary and				Currently, buildings are not design for the "worst
alternative escape routes if the main egress paths				of the worst" on the likelihood of the event and
could become unavailable. Failure to develop an				its consequences for any threat or hazard
exit strategy is a key factor in many large loss				scenario, including hurricane, flood, tornado,
fires.				earthquake, or fire. Should future high-rise buildings
Recommendations				be designed to protect against the most frequent
Following the investigations conducted under the				and likely extreme events utilizing redundancy,
National Construction Safety Team Act, one of				reliability, and tenability?
the recommendations in the National Institute of				Disasters cannot be prevented, but preparedness
Standard and Technology (NIST) World Trade				can minimize the damages and losses that caused
Center (WTC) collapse Report for the improved				by disasters. The World Trade Centre towers in
in building evacuation system designs is that all				New York were emptied thrice in three decades:
high-rise buildings over 20 stories be designed, or				on 9/11, the 1993 bombing, and the 1977 bomb
existing structures be reviewed for retrofitting, to				threat. Better occupant preparedness for
accommodate timely full building evacuation of				evacuation during emergencies, and incorporation
occupants due to building-specific or in large scale				of building exit strategy, would allow all occupants
emergencies. The recommendations include				an equal opportunity for evacuation and facilitate
facilitate safe and rapid egress, methods for				emergency response access.
ensuring clear and timely emergency

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Building Exit Strategy

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