Special Consideration
Notification challenges in large assembly occupancies
BY WAYNE D. MOORE
Assembly occupancies can often present many different challenges to occupant notification. NFPA 101®, Life Safety Code®, or building codes provide limited prescriptive design guidance to assist designers in addressing these challenges. The type of occupant notification most often used in assembly occupancies generally relies on an emergency communications system. Although using such a system would seem both obvious and relatively easy to design for an assembly occupancy, each type of assembly occupancy presents unique requirements that any system design must meet to provide effective notification.
For example, the building codes require that communications systems in stadiums, arenas, and grandstands use a performance-based design. Additionally, due to a 2008 U.S. Federal Court case, the systems must meet accessibility requirements. This means that persons with hearing impairments who attend events at stadiums, grandstands, and arenas require a means of equivalent communications in lieu of the public address system. As you might guess, the occupant notification will present specific challenges due to the number and diversity of those attending the events.
To comply with the federal law, the codes now require captioned messages in these occupancies in addition to the voice messages. These text messages must be delivered at the same time as the pre-recorded or real-time voice messages. Additionally, because these messages can also include real-time messages explaining the actions the occupants need to take in the event of an emergency, the requirements of NFPA 72®, National Fire Alarm and Signaling Code, apply to the captioning systems.
Such a captioning system falls within the scope of Chapter 24, “Emergency Communication Systems,” in the 2016 edition of NFPA 72. The code defines an emergency communications system (ECS) as a system designed for life safety that indicates the existence of an emergency and communicates the appropriate response and action. A review of the Chapter 24 requirements reveals that the broadcasted messages must correlate with an emergency response plan developed during a risk analysis by project stakeholders. The fire code official must approve that plan.
Because these systems fall under the category of mass notification systems, subsection 24.3.11, “Risk Analysis for Mass Notification Systems,” also applies. This subsection states that “each application of a mass notification system shall be specific to the nature and anticipated risks of each facility for which it is designed,” and that “the detail and complexity of the risk analysis shall be commensurate with the complexity of the facility for which the mass notification system is designed.”
The facility's risk analysis must also take into account certain types of potential events—the code acknowledges that these events do not necessarily include all possible scenarios, but rather the general categories of events that the risk analysis shall consider. Those events include natural hazards caused by geological, meteorological, or biological events; human-produced hazards from accidental or intentional events; and hazards caused by technological events.
Obviously, the risk analysis for large assembly occupancies like stadiums must include a review of the extent to which occupants and staff receive notification based on the particular event. The results of this review will become the basis for development of the ECS provisions for the facility’s emergency response plan.
The important take-away from these notification requirements is that designing emergency communications systems for large assembly occupancies requires a strong communications systems background, as well as a thorough knowledge of the code.
WAYNE D. MOORE, P.E., FSFPE, is vice president at JensenHughes.