Fire Alarms for the Future

CSE: Have you noted any significant changes in how fire-alarm systems are set up in buildings since the events of 9/11?

HEIN: Many people are beginning to recognize the importance of fire-alarm systems as part of a comprehensive security system. We've also seen a keen interest in emergency-evacuation systems. Since the fire system supervises all audio system functions, its place in the mind of security personnel has become paramount.

Another trend since 9/11 is the increased use of CCTV equipment. Obviously, having a camera pan-tilt-and-zoom based on a specific fire detector input provides a visual indication of the location, and could give responders insight into what to expect.

CLARK: The most significant changes we've noted are those related to survivability. More often than not, we find requirements for redundant circuits, especially in voice-evacuation systems for high-rise buildings. There is also increased demand for better intelligibility or clarity in voice-messaging systems.

HEIN: Fortunately, there's been a lot of technological advances facilitating these changes. For example, audio signals can now be transmitted digitally throughout the building, but converted back to an analog signal close to the speakers. This eliminates electrical noise typical of lighting ballasts and other high-voltage circuits. It also permits multiple messages—up to eight—that can be sent over a single pair of wires.

This also allows unique voice messages to be broadcast simultaneously providing area-specific instructions based on the initiating event.

Of course, there's also been a lot of human factor interface improvements including large multi-line LCD displays, color graphic maps and closed-circuit television pictures based on alarm-specific information.

CSE: On the subject of communications, many fire devices are now intelligent and therefore have the capacity to interface with other building systems. Has the need for more comprehensive control systems pushed greater levels of system integration?

SHORT: Since 9/11, the integration of security and fire-alarm systems is becoming more common, as well as the connection of fire-alarm systems to the building automation system. It's basically owner-driven because it cuts costs, eliminating an entire cable and conduit loop since both systems are monitored and controlled over the same cables. Also by allowing fire-alarm systems to be monitored off site, the building owner does not need a separate security person monitoring at odd hours of the day.

CLARK: And in the not too distant future, users will be able to receive e-mails of alarm and trouble events on wireless devices.

SHORT: Another factor contributing to the need for greater system integration is the increasing popularity of green building design, which often incorporates large quantities of natural light. Since glass atriums are an ideal way to do so, the integration of fire-alarm systems and HVAC smoke-control systems becomes necessary. For example, beam-type detectors can be equipped with addressable control modules that are integrated into the smoke-control fans. Should the beam detectors sense any type of smoke in the atrium, they signal for the HVAC smoke control system to start up.

CLARK: There's definitely a demand for centralized command and control, especially in larger buildings. More and more, we find that the specification of the BACnet protocol is finally taking hold. Owners seem to want one-line responsibility for service of all of their building systems including HVAC, security/CCTV, card access and fire. This requirement is pushing manufacturers toward complete integration. Sometimes this is proprietary, depending on the manufacturer, and sometimes it is an open architecture using published building communication protocol standards such as BACnet or Echelon's LonWorks.

Some of the limiting factors revolve around standards issues. While customers may want to integrate their systems, the local authority having jurisdiction usually requires UL-listed components. As an example, if the fire-alarm system manufacturer offers a UL-listed BACnet gateway that permits fire signals to be transmitted to another manufacturer's HVAC system, it is only UL-listed with the fire system, not the HVAC system. Therefore, the entire system may not meet UL requirements since the dampers and fans are not cross-listed as UL-864 devices with the fire system. It is possible that the only answer is for the HVAC manufacturer is to submit their devices to UL for cross-listing with the fire manufacturer's HVAC system. But this is an expensive proposition.

MOORE: I agree that integration is the buzzword floating about the industry, and it is indeed occurring, but it should be noted that system complexities and attendant costs that result from complete building systems integration seem to be dampening the desire to "totally" integrate all building systems.

Total building systems integration will be driven primarily by perceived cost savings, but the fear of putting all of the eggs in one basket—without assurance that a single fault won't take down critical systems—will continue to slow total building systems integration.

HEIN: It takes education, including the authority having jurisdiction. The major system providers are now all offering some level of integration, and by educating the AHJs, who have traditionally resisted integrating these functions, we have seen a mind change. Moreover, many AHJs have expressed an unforeseen benefit to integrating fire systems since most security systems are active, rather than passive, making maintenance a high priority.

CSE: On the subject of education, what are some common pitfalls engineers and building owners encounter when it comes to designing and utilizing fire alarm systems?

MOORE: Not understanding the limitations of the detection portion of the system. Second, not informing owners that the building codes traditionally require only partial detection, and that required limited detection—in other words, just meeting the code—may not meet the owner's fire-protection goals.

Finally, a common engineering error is assuming the equipment can make up for mistakes in the design process.

Owners, on the other hand, often make the assumption that the AHJ will ensure that the fire-alarm system will be installed properly. The AHJ is not responsible for monitoring the quality of the installation, nor is he or she responsible to enforce the specifications of the design engineer.

CLARK: In our experience, most problems occur when the project is design-build, rather than driven from a specification. Having said that, we have also seen projects where the specification called out Class A wiring, but the electrical designer never provided a return conduit path. It is truly amazing how weekly progress and informational meetings can make or break the project.

Sometimes problems can come out of left field, when the architect objects to the color or design of a device that may destroy the aesthetics.

SHORT: Back to the notion of codes. In some states there can be contradictions. For example, in Pennsylvania, the ANSI/BOCA code indicates that sprinklers must be installed in the elevator shafts of all buildings that are "fully sprinklered." However, the Pennsylvania Elevator Code does not allow anything in the elevator shafts. To resolve this issue, a variance must be obtained from the state in order to install the system per ANSI codes.

Another common pitfall is inadequate quantities of audible indicating devices. The NFPA and ADA requires that the audible level of fire-alarm signals be 15 dB above the ambient level for the area. Many times, designers do not show enough audible horn devices to produce this output in higher ambient sound areas such as manufacturing facilities. In facilities requiring voice evacuation systems, engineers often install an inadequate number of speaker devices which creates inaudible voice evacuation messages.