An overview of fire alarm notification strategies

A review of several fire alarm notification strategies that are permitted by the IBC, NFPA 101 and NFPA 72

According to the 2024 Edition of the International Building Code (IBC), it’s purpose is, “to establish the minimum requirements…for providing a reasonable level of life safety and property protection from the hazards of fire, explosion or dangerous conditions.”

One of the primary ways the IBC establishes a reasonable level of life safety is by requiring a means to make building occupants aware of the presence of smoke, fire or other related hazards and, in certain cases, providing further instructions regarding how to respond to such hazards. This concept, which the IBC calls “occupant notification,” has existed for decades, but continues to evolve with the advancement of fire alarm technologies and the increasing complexity of the built environment.

Full building notification

Full building notification (also referred to as “total evacuation”) is the most-common notification strategy used in fire alarm system design. The concept is quite simple: upon receipt of an alarm signal, all notification appliances in the building operate simultaneously. The intended outcome is that all occupants in the building immediately begin evacuation. This strategy is the standard requirement for notification in both the IBC and in NFPA 101: Life Safety Code. Full building notification can be implemented in all types of fire alarm systems, including conventional, addressable and emergency voice/alarm communications systems.

The full building notification strategy is the simplest, from both a design and installation standpoint. Since any alarm signal results in notification throughout the building, the fire alarm sequence of operations is straightforward and there is minimal programming needed at the fire alarm control unit (FACU). Full building notification also has the design advantage of having no requirement for pathway survivability, assuming there is no occupant relocation.

However, there are a variety of situations where full building notification may not be the best option. High-rise buildings or buildings with a large total occupant load pose a particular challenge, since it may take a considerable amount of time to fully evacuate such a facility.

Partial notification

Partial notification (also referred to as “partial evacuation” or “selective notification”) involves notifying only certain areas in a building. Generally, occupants who are closest to the location of the fire or other hazard are notified and instructed to evacuate the building or, potentially, to relocate to another portion of the building.

Partial notification systems have the advantage of notifying a small portion of the building population, allowing for specific messaging and instruction to be provided. This also allows for easier evacuation for those occupants, who otherwise may have been impeded by evacuating occupants from other areas of the building. The fire alarm system can also be used to notify occupants outside of the fire area to defend in place or avoid certain areas of the building.

In high-rise buildings, partial notification is frequently used to notify occupants on the fire floor as well as one or two floors above and below the fire floor. In buildings with large footprints, partial notification can be used to only notify occupants located close to the fire threat. Health care facilities often utilize partial notification, along with other strategies described in this article.

Partial notification is specifically permitted by the IBC and NFPA 101 in the following situations:

• In high-rise buildings, where notification is required on at least the alarming floor, the floor above and the floor below.

• Where total evacuation of occupants is impractical due to building configuration.

Other partial notification approaches could be used when specifically approved by the authority having jurisdiction (AHJ).

From a design and installation standpoint, partial notification is more complex than full building notification. First, the responsible engineer must determine the extent of the partial notification strategy based on the building and local code/AHJ requirements. This functionality must then be clearly documented in the fire alarm sequence of operations. Second, during installation, the FACU must be programmed correctly so that activation of an initiating device results in notification only to the intended notification zones. In larger facilities, this could involve a substantial amount of programming. Finally, the testing of fire alarm systems utilizing partial notification can be more involved since the testing must verify that each initiating device results in notification to only the intended notification zones.

Private mode signaling

According to NFPA 72: National Fire Alarm and Signaling Code, private mode signaling is a notification strategy where audible or visual signaling occurs “only to those persons directly concerned with the implementation and direction of emergency action initiation and procedure in the area protected by the fire alarm system.” Essentially, fire alarm systems operating in the private operating mode only notify people who are responsible for carrying out the building’s emergency action procedure.

The most common use of private mode signaling is in institutional and health care occupancies, where many occupants are incapable of evacuating themselves. For example, in a hospital emergency department, private mode signaling may be programmed to only notify a nurses’ station instead of the entire department and patient rooms. The personnel at the nurses’ station would be notified and could implement the emergency action plan in response to the threat or hazard.

Private mode signaling is permitted in Group I and M occupancies by the IBC, and is permitted in NFPA 101 where, “occupants are incapable of evacuating themselves because of age, physical or mental disabilities, or physical restraint.” When used in health care facilities, the private mode signaling design must typically also comply with centers for Medicare and Medicaid services and NFPA 99: Health Care Facilities Code requirements.

It’s important to note that most facilities do not exclusively use private mode signaling. In health care facilities it is common to use private mode signaling in certain areas, such as emergency departments or operating rooms, and use public mode in other areas, such as cafeterias or waiting areas. Because of this complexity, the engineer must coordinate the design of the fire alarm system with the emergency action plan for the building. This coordination must occur early in the design process, since areas designated for private mode signaling will have a reduced number of notification appliances and it’s required that the configuration is incorporated into the facility’s emergency response plan.

Positive alarm sequence

A positive alarm sequence is a method that allows for a temporary delay in notification while an investigation is conducted. When an initiation device activates, a signal immediately occurs at the FACU, where qualified and trained personnel have up to 15 seconds to acknowledge the signal. If the signal is not acknowledged within 15 seconds, the fire alarm notification sequence commences immediately. If the positive alarm sequence signal is acknowledged, an alarm investigation phase begins and the qualified personnel have up to 180 seconds to evaluate the fire conditions.

If the qualified personnel determine that there is no fire threat, they can reset the system within the 180 second period and building occupants will not be notified. However, if the system is not reset, or a second detection device activates within the 180 second period, the fire alarm notification sequence commences immediately.

The use of a positive alarm sequence can be helpful in buildings where evacuation of occupants is particularly challenging. The alarm investigation phase allows for qualified personnel to confirm the presence of fire or another threat before commencing building notification and evacuation.

However, a positive alarm signal is clearly not appropriate for all facilities. The use of a positive alarm sequence is limited to facilities where qualified and trained personnel are available to respond. NFPA 72 defines a qualified professional as “a competent and capable person or company that has met the requirements and training for a given field acceptable to the AHJ.” Many facilities do not have qualified personnel available to respond at all times, and therefore cannot utilize a positive alarm sequence. Engineers also must give careful consideration to the potential risks of delaying occupant notification and the commencement of evacuation. Unless other fire protection and life safety systems are present, such as automatic sprinklers and fire resistance rated construction, the risks of this delay could outweigh the potential benefits.

Historically, use of a positive alarm sequence has been limited to fire detection devices such as smoke or heat detectors. However, starting in the 2022 edition of NFPA 72, manually activated initiating devices, such as a manual pull station, can be included in the positive alarm sequence, if approved by the AHJ.

A positive alarm sequence is permitted by NFPA 101 in select occupancies, but it is not specifically referenced or permitted within the IBC. Full requirements can be found in NFPA 72 Section 23.8.1.2. In all cases, approval by the AHJ is required.

Presignal feature

Fire alarm systems with a presignal feature are programmed so that an initial fire alarm signal sounds only in certain, constantly attended locations, such as a control room, control office or fire brigade station. If applicable, the signal also transmits to a remote supervising station. Upon receipt of this initial alarm signal, the intention is that qualified personnel would immediately begin investigation to confirm the presence of a fire threat. Typically, the responding fire department or fire brigade also commence their response plan upon receipt of this initial signal. While this initial response occurs immediately, occupant notification does not occur unless it is manually initiated, typically at the constantly attended location.

The presignal feature can occasionally be confused with a positive alarm sequence, but one key difference is the reliance on manual activation of the notification system. A presignal feature fully relies on manual activation, whereas the positive alarm sequence initiates notification automatically if the initial signal is not acknowledged within 15 seconds or if the system is not reset by qualified personnel within 180 seconds.

For the same reasons as a positive alarm sequence, use of a presignal feature is not suitable for all buildings and occupancies. The IBC specifically requires AHJ approval to implement a presignal feature in a fire alarm system. The new occupancy chapters in NFPA 101 do not permit a presignal feature, however, it is allowed in certain existing occupancy chapters.

Alarm verification

Alarm verification is a feature to reduce unwanted alarms from smoke detectors. When a fire alarm system is programmed to use alarm verification, acceptance of a valid initiation signal from a smoke detector can be delayed by up to one minute. Practically, if a smoke detector is programmed for alarm verification, upon initially detecting smoke, the detector will reset for a specified amount of time of up to one minute. If a sufficient concentration of smoke is still present after that specified amount of time, the FACU will accept a valid alarm initiation signal and proceed with initiating the notification sequence. If there is an insufficient concentration of smoke after the specified amount of time, no notification will occur.

The alarm verification feature is typically not programmed initially, rather only when unexpected or transient conditions are causing unwanted alarms. Alarm verification is not intended to compensate for improper design of a fire alarm system, such as using the wrong type of detector in areas prone to nuisance alarms. This feature can only be used on smoke detectors and is not appropriate for other types of initiating devices.

Alarm verification is permitted by NFPA 72, but is not directly referenced in the IBC or NFPA 101. It is important to note that the fire alarm signal verification concept referenced for supervising stations in Chapter 26 of NFPA 72 is different from the alarm verification strategy for smoke detectors described here.

Technically, an alarm verification feature is not an overall notification strategy; rather, it is a feature that results in delayed detection, resulting in a corresponding delay in notification.

Implementing fire alarm notification strategies

When designing a fire alarm system, the responsible engineer must consider the characteristics and needs of a specific building and its occupants, the capabilities of the fire alarm equipment being considered and the presence of other fire protection and life safety systems. Most of the notification strategies described in this article require AHJ approval, so the engineer must also take appropriate steps to present and defend the desired strategy in order to facilitate acceptance. Meetings with the AHJ before the permit submission may be necessary to obtain approvals.

Another important consideration is the delay in notification involved with several of these strategies. It is likely an inappropriate and risky approach to combine multiple design choices into one strategy if both involve a delay in notification or fire department response. Such a compounded delay could expose occupants to harmful or untenable conditions in a building. Conversely, an alarm verification feature could easily be combined with a partial notification strategy in a high-rise building, since occupants within the selected zones would be notified immediately upon receipt of a valid alarm initiation signal from a smoke detector.

Many buildings will require fire safety, evacuation and lockdown plans per Section 404 of the International Fire Code. These plans need to contain key information related to fire alarm notification and response. For example, fire evacuation plans are specifically required to contain information explaining if the design is utilizing full building or partial notification. Similarly, the plan must contain the preferred and alternative means of notifying occupants of a fire or emergency, and how those emergencies will be reported to the fire department. While these plans are required once the building is complete and occupied, planning for the implementation of these strategies must coincide with the design of the fire alarm system itself.

Conclusion

There are numerous fire alarm notification strategies that engineers can use to provide a fire alarm system that meets the needs of a particular facility while also providing the required level of life safety and fire protection. Full building notification is the most common notification strategy, but may not be the best solution in all cases. Partial notification and private mode signaling may be a better strategy in certain buildings and occupancies. In some situations, the use of a positive alarm sequence, pre-signal feature or alarm verification feature may be appropriate when approved by the AHJ.

The codes and standards referenced in this article are based on the most recent published editions. However, your project or jurisdiction may fall under a previous edition or could be impacted by local amendments. Always check for which code editions are applicable to your project and whether the AHJ amends the requirements.