The National Institute of Standards and Technology (NIST) is leading a
new effort to rethink the traditional stairwell-centered approach to
emergency egress to embrace a more holistic strategy that includes all
aspects of building design and operation, and their impacts on occupant
safety. Clearly, elevators are a key component of this strategy. The
effort began with a "Rethinking Egress" workshop in March 2008 and will
continue in a series of workshops until a consensus of the engineering
community is reached on how stairs, elevators, and other means of egress
can meet the need for "timely" full evacuation of tall building
occupants and response by emergency personnel.
One of the early conclusions from NIST's investigation of the events
of September 11, 2001, was the need for "timely" full evacuation of tall
building occupants and response by emergency personnel.1 At
any significant height, stairs alone are clearly inadequate. In the late
1990s, NIST had worked with several Federal agencies and the elevator
industry to study the use of elevators as a secondary means of egress
(to stairs). This resulted in requirements in the Life Safety Code (NFPA
101) for elevators in air traffic control towers but an attempt to
extend this to other occupancies in the model codes failed. A collection
of papers from this effort were published.2 In 2003, NIST
took the issue to the American Society of Mechanical Engineers (ASME)
A17 Elevator and Escalator Committee, which develops and maintains the
ASME A17 standards used throughout the US (and harmonized with the
Canadian elevator standard CSA B44). It was agreed to jointly organize a workshop to assess the
feasibility of elevators that would be safe to use in the event of a
fire in a building.
This workshop was held in March 2004, and there was a consensus among
the fire service and elevator industry that it was feasible with
current technology to make elevators safe for use by both occupants and
the fire service in a building with a fire condition. The key
observation leading to this consensus was that the requirements
implemented in the 1980s in the ASME A17.1 standard was effective in sensing the onset of hazardous
conditions and taking elevators out of service ahead of unsafe
In the 1970s, there was a small number of incidents where occupants,
firefighters or the fire itself, called an occupied elevator to the fire
floor and opened the door onto untenable conditions (e.g., First
Interstate Bank fire3). Light beams that prevent the landing
doors from hitting passengers when they close were blocked by smoke,
holding the doors open and preventing the car from leaving. The response
from the elevator industry was twofold. First, firefighters' emergency
operation (FEO) was developed and mandated on all new and upgraded
elevators. FEO involves smoke detectors located in every elevator lobby
and machine room that, when activated, take all elevators out of
service, returning them to the designated level (of exit discharge)
opening the doors, and locking them out of service. This is called Phase
I recall. If the fire is on the designated level, the elevators are
sent to an alternate level. The second industry response was to require
signs in every elevator lobby warning not to use the elevators in fires,
but to use the stairs.
The elevators are intended to be placed into Phase I recall on
activation of an elevator lobby or machine room smoke detector and not
for any other alarm in the building. Thus, the elevators will continue
to operate in what is called normal service with a fire in the building
unless Phase I is activated. Fire departments have a manual means to
activate Phase I, which some utilize in order to take control of the
elevators and prevent occupants from unknowingly traveling to the fire
floor or becoming entrapped. Once on Phase I, firefighters can place
individual cars into a manual operation mode called Phase II with a
firefighter's key in a keyswitch located in the car. Phase II operation
does not respond to hall calls and utilizes a special operating mode for
the car controls that reduces the risk of the firefighter being exposed
to fire conditions, including disabling the door light beams (see ASME
Based on the 2004 workshop consensus that elevators could continue to
be used safely with a fire in the building until Phase I was initiated,
ASME organized two task groups (one on use of elevators by firefighters
and the other on use of elevators for occupant egress) to carefully
study any hazards that might result and the means to mitigate these
hazards. These task group activities are nearing completion, and a
second workshop to share the results of the task group deliberations
(including a several-hundred page hazard analysis) is planned for
In the mid-1980s, the British adopted a requirement for a firefighter
elevator as part of a firefighting shaft in all new high-rise buildings
(>30 m). They developed and published a standard5 which has recently been converted (with little change) to a European standard.6
These firefighter elevators are now common in tall buildings in England
and other countries that traditionally follow British Standards. Not
surprisingly, the ASME work is leading to recommendations that are very
similar to the British/European standard.
Due to the high level of training and preplanning common to fire
department operations (and especially high rise firefighting operations)
the fire service should be familiar with the system and its safe
operation (ASME publishes ASME A17.43, as a training guide on
elevator emergency operating procedures for the fire service). This is
not true for occupant use elevators, so the occupant egress elevator is a
more complex issue to the extent that their use differs from the
occupants' everyday use of the system.
Current thinking (not yet finalized by the ASME task group) is that
on any fire alarm in the building, the firefighter elevator(s) will be
placed in Phase I to await the arrival of the fire department at the
level of fire department access. The remaining elevators will evacuate
the occupants from the fire floor, two floors above and two below, to
the level of exit discharge and then be taken out of service to control
occupant movement while the situation is assessed by the fire
department. Such a phased (or partial) evacuation procedure is commonly
followed in high rise buildings using the emergency voice evacuation
system to direct occupants on the five floors to the stairs and (in some
cases) informing occupants in the rest of the building to await further
Should the incident commander decide that full building evacuation is
necessary, the elevators would be placed into full evacuation mode,
unloading the building from the top down. The system would follow this
top down priority, ignoring hall calls, except that these would register
that occupants are awaiting elevators on those floors. If these floors
had already been evacuated, cars could be sent back or fire service cars
operating on Phase II used to collect occupants.
Each floor would have a fire and smoke rated elevator lobby to
provide a protected waiting space and that provides a barrier from the
fire. This would delay automatic activation of Phase I, which would terminate elevator evacuation. Informational
displays in the lobbies would assure occupants that the elevators are in
service evacuating people, and a direct access to an egress stair from
the lobby would provide an egress path if the elevator evacuation is
halted. A pressurized hoistway would protect the elevator and lobby from
smoke, and provisions to protect the elevator components from water are
included. Emergency power, protection of the power and control wiring,
and protection against water intrusion rounds out the protection
While both firefighter and occupant elevators have additional costs
for safety features, the costs are low compared to the cost of wider or
more egress stairs. It is interesting to note that the elevator industry
design practice for normal use (to meet the demands of the start and
close of the business day) results in a number, capacity, and speed to
permit the self evacuation of 100% of the building population in 30
minutes to one hour (based on an industry standard design handling
capacity of 12.5%7).
The benefits of using elevators are so obvious that the building
codes are changing rapidly and most tall buildings are being outfitted
with elevators for egress and access even before the codes and standards
can be changed. In their 2009 editions, the International Building Code8 (IBC), NFPA 1019 and NFPA 500010 require fire service elevators in all new buildings over 120 feet (37 m). The City of San Francisco adopted (effective in
January of 2008) a change to their building code requiring fire service
elevators in new buildings exceeding 200 feet11 (61 m). Fire
service elevators are included in the designs of Freedom Tower (NYC),
Burj Dubai (UAE), Chicago Spire (Chicago) and many others.
NFPA 101 and NFPA 5000 incorporate an adoptable annex containing
requirements for occupant evacuation elevators but do not require their
use in any occupancy or any threshold building height. The IBC 2009
contains similar requirements in the body, but also no requirement by
occupancy or height threshold. This approach was considered more
appropriate for such a significant code change. Occupant elevators are
also incorporated in Freedom Tower, Burj Dubai, Chicago Spire, One
Financial Center Shanghai (a modified approach where the express
elevators normally serving the observation deck will stop at the
required refuge floors in a fire) and others.
Richard Bukowski is with the National Institute of Standards and Technology.
Final Report of the National Construction Safety Team on the Collapses of the World Trade Center Towers. NIST NCSTAR 1. National Institute of Standards and Technology, 2005.
Morris, J., First Interstate Bank Fire – What Went Wrong? Fire Prevention, No. 226,
20-26, Jan/Feb 1990.
Guide for Emergency Personnel, ASME A17.4-1999, ASME New York.
BSI 5588, Part 8. "Fire precautions in the design, construction and
use of buildings. Code of practice for means of escape for disabled
people," British Standards Institution, London, 1999.
EN 81-72, "Safety rules for the construction and installation of lifts
- Particular applications for passenger and goods passenger lifts -
Part 72: Firefighters," European Committee for Standardization (CEN),
Strakosch, G.R., The Vertical Transportation Handbook Third Edition, John Wiley & Sons, Inc., New York, 1998.
International Building Code, International Code Council, Falls Church, VA, 2009.
NFPA 101, Life Safety Code, National Fire Protection Association, Quincy, MA, 2009.
NFPA 5000, Building Construction and Safety Code, National Fire Protection Association, Quincy, MA, 2009.
San Francisco Fire Code, Section 5.08, Jan 2008.
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