A trio of skyscrapers: the Petronas Towers in Kuala Lumpur, Malaysia, Chicago's Sears Tower, and the Taipei 101 in Taipei, Tawain. (Photographs: AP/Wide World)
Proposed NFPA code changes for high-rise buildings
NFPA Journal®, March/April 2007
By Milosh Puchovsky, P.E.
The first round of meetings addressing proposed changes to the 2009 editions of NFPA 1, Uniform Fire Code TM, NFPA 101®, Life Safety Code®, and NFPA 5000TM, Building Construction and Safety Code TM , has recently concluded. A number of proposals focus on improving the safety of occupants and emergency responders in high-rise buildings. If ultimately accepted, these proposed changes will affect the way in which high-rise buildings are designed, constructed, and operated in the future. A more formal debate on the proposed changes is expected over the next few months as the final outcome of any suggested code revisions will not be decided until July of 2008.
A Renewed Focus
The collapse of the
The Advisory Committee worked to identify the needs and emerging issues concerning the high-rise building environment and developed specific action items for NFPA technical committees to consider when revising their documents. In developing the action items, the Advisory Committee considered the recommendations put forth by the National Institute of Standards and Technology (NIST) as documented in its study of the collapse of the
NFPA 101 and other codes are specific about their goals, objectives, and underlying assumptions. New language better articulates this information and further expands upon the concept of emergencies similar or comparable to fire. In this regard terrorist acts are more directly addressed. The fundamental assumptions employed by both NFPA 101 and NFPA 5000 have been clarified to indicate that the protection provisions mandated by the codes are based on the hazards associated with a single fire source and other events having comparable impact on a building and its occupancy. New language further states that protection against certain terrorist acts will generally require protection methods beyond those mandated by the provisions of the code.
Planning for Emergencies
It is proposed that building owners be responsible for preparing and implementing emergency plans for all high-rise buildings. While the code requires that emergency plans be developed for certain occupancy types such as health care facilities, no such requirement previously existed for high-rise buildings. It is believed that the development and implementation of an emergency plan tailored to specific high-rise properties will prompt better pre-event operation, response, and coordination of building occupants, emergency responders, and others and ultimately result in a more desired outcome following emergency events.
To the extent possible, the emergency plan should not to be limited to fire hazards only but should address other hazards affecting life safety regardless of whether the hazard is initiated by accident, pre-meditated actions, or natural causes such as a hurricane. To aid in the development of such emergency plans, annex material identifying the elements of an emergency plan has also been proposed, as has information pertaining to the updating and maintenance of such plans.
One of the NIST recommendations calls for tall buildings to be designed to accommodate timely full building evacuation of occupants when required in building-specific or large-scale emergencies, such as widespread power outages, major earthquakes, fires, terrorist attacks, etc. While NFPA 101 and NFPA 5000 establish minimum criteria for the design of egress facilities so as to allow prompt escape of occupants from buildings, they also allow for the prompt relocation of occupants into safe areas within the building as is normally the case in health care 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 the various types of evacuation and defend-in-place concepts addressed by the code, and why certain strategies are preferred over others in certain occupancy types. It is also more clearly indicated that in larger buildings, especially high-rise buildings, all evacuations—whether partial or total—should be managed to sequence and better control the order with which occupants are evacuated from their origin areas and make use of available means of egress. This includes the consideration of the evacuation capabilities and needs of occupants with disabilities, either permanent or temporary.
Awareness of Exits
In tall buildings, stair towers might incorporate horizontal transfer passageways as the stair extends to the level of exit discharge. As experienced during the evacuation of the
New information on evacuation diagrams reflecting actual floor arrangements and exit locations is proposed, as egress paths with multiple turns can often be confusing as to which exit route will lead to the closest exit, especially during emergency situations. Where specifically required by an occupancy or building type, such evacuation diagrams are to be posted and oriented in a location and manner acceptable to the authority having jurisdiction. A related proposal calls for floor proximity egress path marking to be provided in interior corridors of new high-rise buildings. This proposal was not accepted by the technical committee, as no clear measurable effect on safety was demonstrated by the submitter of the proposal. In addition, the committee expressed concern with the proper and uniform application and enforcement of such marking system provisions.
Arrangement of Means of Egress
Both NFPA 101 and NFPA 5000 specifically address the remoteness of exits and exit access doors but do not specifically refer to the remoteness of exit access or exit discharge. Depending upon the interpretation of this provision, exit access or exit discharge could be arranged so that a single fire incident could impact an occupant’s ability to reach a point of safety. To clarify the committee’s position on this matter, the provisions concerning remoteness of the means of egress were revised to specifically include exit access and exit discharge. Changes as to how the remoteness between exits along a corridor is to be determined have also been proposed.
Egress Widths and Capacity
The 2006 editions of NFPA 101 and NFPA 5000 already include text requiring 56-inch (124-centimeter) minimum stair widths for those stairs serving 2,000 or more occupants. This provision typically applies to tall buildings 14 or more stories in height and serves to facilitate occupant egress and counterflow of emergency responders traveling up the stairs. A proposal for the 2009 editions calls for the expansion of this provision for essentially all exit stairs and the elimination of the current 44-inch (111-centimeter) minimum width criteria. While this proposal was rejected by the committee for insufficient substantiation documenting problems with current stair designs, another related proposal was accepted. Where stairs exceed the 44 inches in width, the stairs are permitted to accommodate an increased occupant capacity as calculated by a new formula in the code. This provides an incentive for building developers to voluntarily increase the size of their stairs. In connection with the need to provide sufficient width for exit passageways into which exit stairs discharge or which serve as horizontal transfer corridors in an exit stair system, new requirements were developed to better balance the occupant capacities between vertical and horizontal exit components.
Another proposal addresses the balanced distribution of occupant loads for egress. For new construction where more than one means of egress is required, the means of egress is to be of such width and capacity that the loss of any one means of egress leaves available not less than 50 percent of the required capacity. This new wording ensures a more balanced capacity for egress. The new provision specifically requires that the loss of any one means of egress not reduce the overall required capacity to less than one-half the occupant load served. For example, where two means of egress are required, each must accommodate one-half the occupant load served. Where three or more means of egress are required, the percentage of the overall occupant load that each must accommodate is not specified; however, where the loss of any one means of egress occurs, the remaining means of egress must provide capacity for at least one-half the occupant load.
Elevators for Evacuation
In response to the potential need for more timely evacuation of occupants in tall buildings, new provisions allowing the use of elevators in certain situations prior to Phase I Emergency Recall Operation as mandated by the Firefighters Emergency Operation provision of ASME A17.1, Safety Code for Elevators and Escalators, have been put forth. Elevators remain usable after initiation of the building fire alarm system, provided that the elevators have not been recalled upon detection of smoke in the elevator lobbies, machine room, or hoistways. In such situations the elevators remain operable and are available for occupant evacuation.
The new provision paves the way for a broader concept currently being explored which would allow the use of elevators as a component of the means of egress. As currently written, the proposal only allows elevators to be used for evacuation, and does not permit the elevators to satisfy the requirements for the number, capacity, or arrangement of means of egress. Even so, the proposal introduces a major shift in the traditional way in which elevators have been considered for use in emergency situations, as building occupants have traditionally been instructed not to use elevators in fire and similar emergencies. Because of this, the proposal includes details about occupant information features and training as well as additional details about associated detection, alarm, and communication equipment, sprinkler systems, elevator components, electrical power and wiring, and the concept of an occupant evacuation shaft system.
Supplemental Evacuation Equipment and Helicopter Landing Facilities
Introduced during the code cycle for the 2006 editions, proposals regarding supplemental evacuation equipment were not incorporated into the code. A new proposal addressing such equipment has been introduced for the 2009 editions and is intended to provide guidance to building owners and others considering the voluntary use of such systems and equipment. The new provisions cover supplemental escape devices and systems as well as platform rescue systems. If provided, the evacuation equipment is intended to serve in a supplemental capacity and will not satisfy any code requirements pertaining to means of egress. While the proposal is not specific to high-rise buildings, it is expected that such evacuation equipment would be considered for tall buildings.
Associated with supplemental evacuation equipment is a proposal that calls for helicopter landing facilities on all high-rise buildings. As high-rise building emergencies can be the result of hazards other than fire, such as natural disasters, crime, and terrorism, the proponents of this proposal argue that the availability of such facilities could aid in the evacuation of occupants and deployment of emergency responders. The technical committees rejected the new provisions during this stage of the revision process due to confusion with the intended application of the requirements.
Collapse Prevention Scenarios
Chapter 5 of NFPA 5000 includes provisions for the performance-based design of buildings. One set of design scenarios to be considered includes collapse prevention. The section on design scenarios has been revised to specifically address certain types of high-rise buildings. For buildings of category III or IV as defined by ASCE/SEI 7 Table 1-1, the collapse prevention scenario is to include a fully developed compartment fire that proceeds until all fuel in the compartment is depleted. The fire scenarios previously included in NFPA 5000 are scenarios associated primarily with life safety and these scenarios are not considered to be sufficiently challenging to a building structure. Guidance on determining the fire load has also been included as part of this code change.
Related proposals call for more robust elevator and stair shaft enclosures. For buildings over 420 feet (128 meters) in height, at least one stair shaft and one elevator shaft are to be designed to prevent collapse into the shaft enclosure. The shafts are also to have a capacity to resist a uniform pressure of 2 psi applied perpendicular to the face of the shaft enclosure. Both of these proposals were rejected, as these requirements are likely to conflict with the objectives associated with design for seismic and wind events.
With regard to the overall topic of increased structural integrity, such as disproportionate collapse, the primary area of expertise on this subject lies with the American Society of Civil Engineers (ASCE) and other structural engineering organizations. It is understood that these groups are studying the associated issues and that code change proposals will likely be developed as appropriate.
Dedicated Enclosures for Emergency Responders
Several proposals call for increased safety features in tall buildings for emergency responders. One proposal calls for an elevator, in buildings over 120 feet (36 meters) in height, to be dedicated for first responder use. To facilitate use of such an elevator, the proposal includes additional details on elevator lobbies, standpipe hose connections, communication systems, electrical power, and elevator machinery spaces. A similar proposal introduces the concept of an emergency personnel response access stair for high-rise buildings. Such a stair would be dedicated to emergency responders and would be within 25 feet (7.6 meters) of the emergency command center. Neither of these proposals was accepted by the technical committees. It was understood that additional information regarding elevator use by emergency responders is being developed. With regard to the dedicated stair, the technical committee believes that first responder objectives could be achieved without a dedicated stair through more diligent development, training, and implementation of a building operations and emergency plan.
Inspection of Fireproofing Material
To improve the overall structural performance of building elements during a fire situation, a proposal for NFPA 1 calls for readily accessible fire-resistant assemblies in high-rise buildings to be visually inspected for integrity as stipulated by the authority having jurisdiction. An approved independent third party is to inspect the assemblies at lease once every five years, and a written report indicating the inspection result findings is to be submitted to the AHJ. The new provisions will require that such spray-on materials be maintained in proper condition throughout the life of the building.
Fire Department Communication
As a partial reply to NIST’s recommendations and the Advisory Committee’s action items on emergency response and communication, a code change proposal calls for a new type of radio communication system and associated equipment to be made available for fire department and emergency responder use. The operational effectiveness and interoperability of such equipment is a key consideration to ensure reliable communication ability on-site and to the respective dispatch and command center. The proposal addresses radio coverage, amplification, testing and inspection, power sources and monitoring, and other factors critical to the effective operation of the system. As noted in the ROP, a technical committee task group has been appointed to further study the associated issues and develop more specific information during the next stage of the code revision process.
Recent high-rise fire incidents have brought to light a greater need for building occupants, emergency responders, and building management to be more aware and be made more aware of the changing conditions of the building and the associated safety and egress systems during emergency situations. While this concept is an underlying precept of the code, there has been no formal mention of it. A proposal more formally introduces this concept and identifies it as an objective of the code. Associated proposals calling for video monitoring of certain portions of the means of egress system have not been accepted by the technical committees, but the central importance of the concept of situational awareness is being recognized. Related information on mass notification systems has recently been incorporated into NFPA 72®, National Fire Alarm Code®. These systems are intended to notify building occupants and first responders about various types of emergency situations including fire emergencies, weather emergencies, terrorist events, biological, chemical or nuclear emergencies, or any combination of these.
To a significant degree, activity associated with the 2009 editions of the codes is a continuation of work initiated during the 2006 code cycles. A number of changes affecting safety in tall buildings as suggested by both NIST and the Advisory Committee have already been incorporated into the 2006 editions of the codes or have been part of the code prior to this.
While a number of proposals have already been introduced, a number of other recommendations require further research if meaningful changes are to be expected. Two such areas include the determination of structural fire resistance and whether additional information from current fire resistance testing protocols can be used in the design process. The other includes our understanding of high-rise building occupant perceptions and assumptions about safety and egress. Through its Research Foundation, NFPA is working to develop a better understanding of these subjects. The results of these studies will be made available to NFPA’s technical committees for their consideration.
The official action taken by the technical committees on specific code change proposals addressed here can be found in the Annual 2009 Report on Proposals (ROP), which is due for publication June 22, 2007. While a technical committee might or might not be in favor of a specific proposal, the relevant issues can continue to be considered in the subsequent stages of the document’s revision cycle. The outcome of any proposed code changes for the 2009 editions is months away. Regardless of their outcome, the debate about the appropriateness of the relevant issues is critical to addressing the needs of high-rise building occupants, and it is essential that such debate occur and be documented.
In this Section:
|Life Safety in Tall Buildings
Changes to the 2009 editions of NFPA 1, NFPA 101, and NFPA 5000 include proposals focused on improving safety in high-rise buildings.
|Fire and Life Safety Challenges in Convention Centers
As convention centers grow larger, the fire and life safety designs of these buildings become more challenging.
Nuisance fire alarms have long been the bane of the commercial high-rise environment. Resolving the problem requires careful study and action.
|Inside Propane Tanks
NFPA’s Technical Committee is recommending changes to NFPA 58 including provisions regarding composite cylinders.