The building automation system can control all aspects of a building or campus, including its fire alarm system. This outlines best practices for integrating a fire alarm into a BAS.
The responsibilities of a chief building engineer are becoming more challenging as technology advances. Bigger and taller buildings are being constructed with an increasing emphasis on energy efficiency and comfort, and the ever-increasing demand to keep construction costs and operating expenses down. In addition, building codes are changing the way these buildings are constructed in order to improve safety with an eye on new construction methods and materials.
There is also the somewhat traditional mind-set among those within the design and engineering community that building automation and fire alarm systems should maintain a significant level of separation with minimal connectivity or interaction. Most of this belief stems from the fear of the unknown and the desire to mitigate risk along with the old adage of “This is the way we’ve always done it.” In reality, the integration of building automation and fire alarm systems can result in overall reduction in equipment, installation, and maintenance costs while still maintaining the level of safety required for these systems to operate.
With the advent of smart building technology, heating, cooling, electrical, lighting, security, and other systems need monitoring and intercommunication for optimized efficiency and operation. With sophistication comes the need for a building automation system (BAS) to allow for nearly seamless operation of these various interrelated equipment.
Like BAS, fire protection and alarm systems have also evolved into sophisticated computer-based systems, which integrate fire detection and emergency communication systems as part of overall building operations during an emergency event.
Often fire protection and alarm systems must interact with other building systems to provide a proper level of protection. While the fire alarm system is fully capable of performing and initiating the necessary actions to accomplish the fire alarm and building systems’ responses, efficiencies can be obtained by integrating with the BAS. These efficiencies include minimizing additional equipment, expediting system acceptance testing, reducing installation costs, and sharing and consolidating information at a central location where all of the building systems can be precisely monitored during emergency incidents.
Smoke control systems are a good example of the marriage of building mechanical systems with fire protection/fire alarm systems. Fans are starting or stopping, dampers are opening or closing, and doors may be closing or unlocking while elevators being recalled. Although both the BAS and fire alarm systems have specific tasks to perform, there is a certain level of priority and sequences that must be followed. Failure to follow the proper priority or sequence may not only be non-code compliant, it may also lead to equipment damage or risk to human life. For example, if a smoke control fan operates before dampers open, ductwork may be damaged or door opening forces may be increased beyond acceptable levels for egress.
Communication
When the fire alarm system takes control of equipment that is not a listed component of the fire alarm control unit, the fire alarm system must either override the natural operating mode of the building equipment or pass off that command via a simple switch or data communications to the building mechanical systems. Likewise, each manufacturer’s BAS has its own protocol for monitoring conditions and communicating operational commands to maintain the proper building environment and efficiency. There are also standard open communication protocols such asLonTalk and BACnet that can be used to communicate with a multitude of equipment from various manufacturers in order to achieve an integrated building system.
The communication protocol for a fire alarm control unit to communicate to and from its indicating (input), initiating (output), and sometimes notification appliances is typically an analog or digital communications signal carried over what is referred to as a signaling line circuit (SLC). Because communications signals are typically proprietary protocol, each SLC is dedicated to a specific manufacturer’s equipment and cannot include connection of incompatible devices that use a different signal protocol.
Therefore, in order to integrate system alarm and control functions with the BAS in a manner other than relay logic, fire alarm system manufacturers had to also design and support the open communication protocols used for building automation, in a manner that would not compromise the integrity or the operation of the fire alarm system. This process of sharing information between both fire alarm and BAS came to be known as bridging, or open gateway processing. Because of the strict code and listing requirements of fire alarm systems, much of this communication has been primarily limited to one-way communication. However, some manufacturers of both fire alarm and BAS do produce equipment such as gateways that are listed for bi-directional communication with their equipment.
The use of these open gateway processors has the potential to eliminate the need for costly interface equipment and enclosures. A single gateway can replace hundreds of conventional or electronic relays and input sensors for control and monitoring while also eliminating the need for multiple wire terminations that can decrease the potential for system failure points.
How to know whether to integrate
There are advantages and disadvantages to consider when determining whether to integrate a BAS and a fire alarm system. The most common consideration is when the building has a complex smoke control system. An integrated system is also seen in facilities involved in process control that may be affected by a fire alarm event. For the purpose of this article, when used primarily in controlling the spread of smoke, integration of the various systems that normally have independent connections helps to facilitate improved communication, redundancy, and cost savings. Additionally, the building engineer will have the ability to determine from a single source what is causing the mechanical equipment to operate, shut down, open, or close.
Take a case of a building with separate building automation and fire alarm systems: When the building engineer receives a call from an occupant complaining about increased temperature or whistling air within the ductwork and finds that the fan is shut down or a damper is closed, the building engineer is more apt to call a controls contractor to investigate the problem before he calls their fire alarm service provider. Should the problem be related to an override of controls by the fire alarm systems, not only does the building engineer have to wait for the controls contractor to diagnose the problem, he also has to call the fire alarm contractor to come out and fix the problem. This process can take time to correct; meanwhile, building occupants are uncomfortable and inconvenienced.
Sometimes this can even lead to finger-pointing between the two service providers as to whose problem it really is. In this scenario, the fire alarm control of a fan or a damper is required to be ahead of the hand-off-auto switch for the power to the equipment so the inadvertent shutdown of the equipment does not inhibit the operation of the fire alarm feature. A failure of the fire alarm system control relay could shut down the fan or close the damper without an alarm being present on the fire alarm system or fault condition occurring on the fire alarm control unit.
With an integrated building automation and fire alarm system, this scenario plays out in a different manner. The BAS, when listed accordingly to UL Standard 864 UUKL listing, to provide code required smoke control functions, can rely on a digital alarm signal from the fire alarm system, passed through a gateway, as the only means outside the BAS to influence control over the building mechanical systems. The responsibility for fan and damper control is solely with the BAS and thus simplifies the troubleshooting process.
Because many components that affect air and smoke movement within a building are shared between HVAC and fire alarm systems, let’s take a step backward in the evolution of the building process. When building systems are being commissioned for proper operation by either an authority having jurisdiction (AHJ) or an independent third-party group, coordination must occur between multiple trades. At this point in the construction process, each trade is independently looking to complete its own scope of work and more often than not is under pressure to finish the specific scope in a designated timeframe. Sometimes this leaves a disconnect between the fire alarm and mechanical trades that results in disruption during start-up and commissioning.
The integrated system approach allows for those individuals responsible for controlling air movement to be focused on proofing and balancing the mechanical system, while the fire alarm contractors focus on the detection and annunciation of the alarm events. Much in the same manner as referenced in the previous example, the problems can get resolved more expeditiously and the systems can be brought on-line.
If we focus on the installation of a building management system (BMS) and a fire alarm system, we see many similarities. Each of these control systems is classified as low-voltage systems that communicate to their respected devices through an analog or digital signal. Their wiring methods and materials are similar, and often their respective equipment is located in the same general area and is performing the same basic functions with one significant difference: the fire alarm system uses individual point addressable monitor and control modules while the BAS uses digital input/output driver assemblies that communicate with different protocols.
Why is this important? Because the BAS still requires individual pairs of conductors to each point being controlled or monitored by the digital input/output module, resulting in more wire being needed and longer installation time.
Creating a code-compliant integrated system
When considering system integration, the ability of the BAS to control a smoke control system operation falls under the auspice of the jurisdiction’s building code, often based on the model building codes. The IBC has been adopted by a large portion of the United States and is used in this article as an example. IBC Section 909 covers smoke control systems, the procedures for determining system parameters, the acceptable methods that may be used to accomplish smoke control, and the requirements to document the system’s actual performance. It recognizes that the smoke control system is a life safety system and must maintain the same high level of reliability required for any type of fire protection or fire alarm system.
Section 909 requires smoke control systems to be initiated by sprinkler system or smoke detection system operation, depending on the type of system being designed. It also requires systems providing control input or output to the mechanical smoke control systems to comply with Section 907 (Fire Alarm and Detection Systems) and NFPA 72: National Fire Alarm and Signaling Code, and states that such systems must be equipped with a control unit that complies with UL 864 and has to be listed as smoke control equipment.
UL 864 requirements cover control units and accessories that are used to meet the requirements of many NFPA standards, including NFPA 72, NFPA 92A: Standard for Smoke-Control Systems, and NFPA 92B: Guide for Smoke Management Systems in Malls, Atria, and Large Areas. Each system is tested by UL, which then lists the complying equipment under the “UUKL” designation in the product directory. The fire alarm and building automation systems must meet these requirements and be listed in order to control a smoke control system and be configured as an integrated system.
Inspection and testing
Integrated systems require enough time to test and to verify that the system interoperability is functioning properly. It is important that the engineer as well as the installing contractor and the equipment vendors understand the impact of these requirements on providing an approved and code compliant installation.
Due to the complexity of these systems and the required integration, testing must confirm that the functions and sequences work correctly under both automatic and manual modes.
The inspection and testing of integrated systems is usually exasperating and time-consuming, and often requires multiple rounds of retesting before all the deficiencies are corrected. This is often caused due to all of these different systems being completed late in the schedule and not enough time to “get the kinks out” prior to final testing. Anything that can expedite the commissioning process is beneficial to the overall project.
One of the advantages of using the BAS as an integrated part of the smoke control system is the system’s ability to modify operating conditions to accommodate actual ambient conditions through the use of VFDs. The design of smoke control systems is based on many variable conditions, including temperature, wind conditions, and the quality or “tightness” of the construction. These conditions tend to make testing and adjusting of the smoke control system difficult at best.
Integrating BAS can help minimize test stress by adjusting the fan speed of individual fans through programming. In a situation of excessive stair pressurization, the individual fan can be adjusted to limit its airflow to the stair, resulting in a lower level of pressure affecting door opening forces. Similarly, for individual zone smoke control system performance, the fan speed can be adjusted on a zone-by-zone basis, based on the fire alarm signal received by the BAS.
The downside to this operation is that the BAS controls are typically located remotely to the fire alarm control panel and the firefighters’ smoke control panel, both of which normally reside in a fire command room. BAS controls and system components are usually located for the convenience of the building’s staff and HVAC equipment. Under test conditions, additional personnel may be required to monitor the BAS controls to make any required modifications.
While modifying fan output for each smoke zone condition is a more expedient method to obtain approval, it also provides future opportunities to inappropriately change the settings, possibly making the system ineffective. Care must be taken to limit access to this programming and provide logging procedures to document when and why changes are made.
Documentation
After all the work is done by the engineers, contractors, inspectors, and the AHJ, the integrated system operation is approved and the owner receives its total cost of ownership and, eventually, its final certificate of occupancy. However, the project is not over. It is critical that the owner receives and carefully stores all record documents related to the integrated system. As a building ages, things change and systems are modified. When changes occur, the contractors making the changes can use the documentation to maintain the interoperability of the integrated system as well as revise the drawings to reflect changes made. In addition, the modified systems should be retested to confirm their revised performance. Documentation of the testing should be incorporated with the existing record documents.
Integrating fire protection and fire alarm systems with BAS can be cost-effective and provide a more efficient operation. It is imperative that the design and installation is well planned and coordinated, and that the system is properly maintained over its lifetime.
