Two additional issues are important in selecting a mass notification system. First is the role of NFPA 72 —the National Fire Alarm and Signaling Code, which, in part, addresses requirements for mass notification systems. Second is the critical importance of using a risk analysis.
NFPA 72 does not tell engineers specifically what to do, according to Richard Roux, senior electrical specialist and staff liaison for NFPA 72 at the National Fire Protection Association. "But it does list a number of mechanisms to get the information to where the people are." Among the options, NFPA 72 considers three layers of mass notification systems, he explains. "The first layer is basically in-building voice communication systems. Layer two covers the wide area exterior to the building, with possibly large speakers outside. Layer three is notifying by individual means, usually using cell phones."
In locations with message signs, mass notification systems may employ these to alert occupants to an emergency and the appropriate action to take. "At a football game, for instance, the Jumbotron broadcasting the game could be used to alert the crowd to an emergency and how to respond to it," says Roux. "NFPA 72 allows the mass notification system designer to develop the best solution for the facility."
"When a mass notification system is installed, the system is required to comply with NFPA 72," explains Woodward. For buildings equipped with a dedicated mass notification system, NFPA 72 provides requirements for the interface, notification, and supervision. In addition, when a mass notification system is interfaced with a fire alarm system, NFPA 72 provides requirements for this interface.
When planning a mass notification system, a risk analysis is basically mandatory. The risks identified for the mass notification system responses dictate the messages required as well as the actual system design. Risk analysis also helps establish an emergency response plan, which determines the procedures needed to protect facility occupants.
A typical risk analysis will consider the unique characteristics of the buildings, areas, spaces, or campuses being covered and evaluate the condition of the occupants. For example, are they primary-school children, or possibly residents in an assisted living facility or medical hospital? Finally, local conditions, equipment, and operations also are considered, and potential events.
These events include those listed by NFPA 72-2013: natural hazards (geological, meteorological, and biological events), human-caused events, both accidental and intentional, and events caused by technology. However, the risk analysis is not limited to this list. For example, Roux notes that the analysis may show the closest police are 11 minutes away: "That is a risk. How are we going to deal with that?"
"The risk analysis needs to cover all events that could possibly happen," says Roux. "And it needs to spell out how to deal with them. So what happens if someone breaks the glass and gets into the building or unlocks the door? What do we do if there is no power on campus?" The concept is to come up with the possible things that can go wrong and then develop a plan for mitigating them.
How Mass Notification Systems Are Used and Their Various Forms
NFPA 72, Risk Analysis Also Important with Mass Notification Systems
Tips on Mass Notification ‘Designers,’ Limitations, and Testing
Kobar Tower Attack Prompted Development of Mass Notification Systems
Combining Fire/Life Safety, Emergency Communication Systems for Mass Notification