How to properly integrate fire alarm systems and HVAC systems

Organizing the coordination with the engineering team is key to a successful system integration project.
By Wayne D. Moore and Larry D. Rietz, JENSEN HUGHES December 13, 2017

This article has been peer-reviewed.Learning Objectives

  • Explain the purpose of fire alarm-HVAC system integration.
  • Recognize how the electrical and mechanical engineers and contractors work together for successful system integration.
  • Understand NFPA 72: National Fire Alarm and Signaling Code to ensure code compliance with system integration.

For engineers, coordination is a term that is critical when integrating a fire alarm system with an HVAC system or building automation system (BAS). Although for contractors installing the systems, this can be difficult. However, coordination at the design stage of the project can help ease the process for everyone involved.

The reason for any fire alarm to connect with an HVAC system or a BAS is strictly to control the spread of smoke from the fire source on a floor (or given area) to all of the other floors (or areas) in a building. For example, a small fire occurred in a newly opened 5-floor apartment building in the state of New York. While a building tenant was washing clothes in the laundry room located on the 1st floor, the clothes dryer was not drying clothes to the tenant’s satisfaction. The tenant decided to place a towel above the dryer to cover an air intake into the dryer plenum. As the tenant waited in their apartment, the towel heated, crystalized, and produced a sizable amount of smoke, although without much actual flame. Figure 1: This graphic is a typical fire alarm sequence-of-operation matrix. A good, detailed fire alarm sequence-of-operation matrix will detail how all inputs and outputs relate to each other. Courtesy: JENSEN HUGHES

The smoke entered the HVAC ductwork, activating the smoke detectors on the 4th- and 5th-floor corridors, which then caused total evacuation of the building. By the time the fire department arrived, the smoke in the corridors on the upper levels had dispersed and neither the fire department nor the tenants could locate the source of the smoke. At about the same time, the tenant on the 1st floor found the burned towel and other minor damage from the now self-extinguished fire and told the fire department what happened. (The fire was not large enough for sprinkler activation, and there was only heat detection in the laundry room.) The building owner replaced the faulty dryer and repaired the minor damage. However, in this example, the transmission of smoke to the upper levels could have been avoided with properly installed and maintained duct-type smoke detection. In this case, the building was small. High-rise and other complex buildings offer different challenges.

As another and more tragic example, on Nov. 21, 1980, a fire on the 1st floor of the MGM Grand Hotel and Casino in Las Vegas sent smoke through the stair and elevator shafts, resulting in significant smoke and loss of life on multiple floors of the building stairwells. Whether on a small or grand scale, smoke movement through HVAC system ductwork presents a significant risk to building occupants.

 Figure 2: This is an HVAC control switchgear with fire alarm control relays located directly adjacent. Proper installation of control relays in accordance with NFPA 72 is critical to proper HVAC interface. Courtesy: JENSEN HUGHESCoordination at the design stage

While model building codes and installation standards have attempted to adequately address this issue, much of the real “coordination” is still left to installing contractors who are often forced to address integration issues that they either know little about, have little direct control over, or even worse, have not budgeted for appropriately. It is important to remember that the engineers involved in the design of these two systems have the responsibility to do the same. Coordination at the design stage will help the installation stage go smoother.

Traditionally, integration between fire alarm systems and HVAC systems has been limited to dry-contact-type relays. This approach allows the fire alarm system to do what it does best (detect, notify, and activate emergency controls) while allowing an HVAC system or BAS to do what it does best (manage the air quality of the building). It also allows individual skilled contractors to focus on their own specialty with fairly limited coordination and interface.

In many ways, NFPA 72: National Fire Alarm and Signaling Code reflects this traditional interface view. The code requirements for emergency control of HVAC systems is found in Section 21.7 of the 2016 edition of NFPA 72, where it states that the “provisions of Section 21.7 shall apply to the basic method by which a fire alarm system interfaces with the heating, ventilating, and air conditioning (HVAC) system.”

Figure 3: This is a poor example of fire alarm control unit wiring, including a wired relay providing HVAC shutdown and off-site supervising station connection.  Poor workmanship results in poor emergency control interfaces. Courtesy: JENSEN HUGHESAs such, many long-standing code requirements remain. For instance, any listed appliance or relay connected to the fire alarm system used to initiate control of protected-premises emergency control functions must be located within 3 ft of the controlled circuit or appliance (NFPA 72-2016, Section 21.7.2). Installing the wiring between the fire alarm control unit and the relay or other appliance must be monitored for integrity.

This requirement can be avoided if the fire safety function is wired in a fail-safe fashion. For example, if the fan that needs be shut down when the fire alarm system smoke detector actuates shuts down automatically if the circuit wiring controlling the fan is cut, then the system is wired in a fail-safe mode and the circuit wiring controlling the fan does not have to be monitored for integrity. This is another instance where coordination between the design engineers is important.

Also, a contractor is allowed to program smoke detectors mounted in the air ducts of HVAC systems to initiate either an alarm signal at the protected premises or a supervisory signal at a constantly attended location or supervising station (NFPA 72-2016, Section 21.7.4). Design engineers performing this work should be aware of this allowance and not specify that an alarm should occur from a duct-type smoke detector. However, beyond these and a few other requirements, NFPA 72 code is rather silent on fire alarm and HVAC interfaces. This is particularly true when an integrated BAS will be used.

Building automation and integration

Figure 4: A typical fire alarm system duct smoke detector on a return air HVAC duct.  Such duct detection is the most basic form of HVAC interface, providing shutdown of the air handling unit upon detection of smoke. Courtesy: JENSEN HUGHESBuilding automation is not a new concept, but it is experiencing difficulties in becoming the norm rather than the exception. BAS appeals to building owners because they can visualize the potential for the BAS to save money and create efficiencies. BAS can provide savings in the initial installation and in future updates. The future updates may become necessary to take advantage of future savings. However, it is often the future updates that can cause difficulties where the BAS has been integrated with the fire alarm system.

As previously noted, the construction process traditionally requires that each of the specialized construction trades complete their tasks essentially independently of each other. However, close coordination between the responsible contractors is required to ensure that the BAS will do what it is supposed to do. The wiring is the backbone of successful coordination. This is why a contractor must truly understand the operational requirements of the BAS before the first cable is installed. Here is where the engineer must ensure that the BAS operational characteristics are explicitly spelled out to ensure everyone involved in the project (including the owner) understands the BAS operation.

As with any complicated wiring system, it’s important to understand the details. Unlike most signed contracts, a contractor should not take an agreement to wire a BAS lightly. It is important that both the engineer and the contractor follow a few key rules, which are outlined below:

  • The contractor should ensure he or she understands how the engineers want the system to work and determine whether or not they have developed an operational matrix to aid in that understanding.
  • The engineer and the contractor need to research the specified products that will be supplied to ensure the products will actually perform as the manufacturer’s marketing and sales people say they will.
  • Inevitably, contractors are going to submit a different vendor if the specifications allow for an “or equal” product. The engineering team must decide whether or not it is in the owner’s best interest to allow for substitutions, and they must verify that the chosen vendors, and even the specific technicians for the job, can make the specified or substituted product meet the operational requirements. Additionally, the engineering team and the contractors must be in attendance for the required acceptance testing, balancing, and commissioning to ensure the integration has been completed according to expectations.

While current practice involves the installation of separate building systems for fire alarm, HVAC control, security, lighting control, and building process automation, the long-term goal of BAS is to seamlessly integrate all of these systems into one BAS. The major drawback to this concept comes from the fact that the suppliers of these systems must maintain their own systems. In the fully integrated BAS scenario, someone must have sole responsibility to ensure interoperability of all of the systems. Some suppliers have recognized the need for interoperability of their systems with other manufacturers and have developed software solutions. Electrical contractors with a strong background in communications may hold an edge when installing BAS, and the engineer may want to include those qualifications as a requirement in the specifications. But inevitably, providing specific training for the contractors for more efficient installations will become imperative.

BAS installation and code compliance

Installing a BAS takes a team effort. This effort requires that the electrical or fire protection engineer and the electrician have some understanding and knowledge of how the electrical work interfaces with the other trades. The design engineer also must ensure that the electrician possesses an understanding of the function and operational design of the BAS.

In addition to the technical knowledge necessary to design and install the BAS, engineers and contractors must always keep code compliance in mind. Unfortunately, conflicting requirements exist within the applicable codes, and as noted, fire alarm codes remain firmly rooted in more traditional methods of integration. NFPA 72 and the authority having jurisdiction (AHJ) work in concert to regulate the design, installation, maintenance, testing, and use of the fire alarm system. Some AHJs do not want the fire alarm system integrated with any other system. They do not want the non-fire alarm systems to interfere with the proper operation of the fire alarm system, which is addressed by NFPA 72. It is incumbent, therefore, on the engineering team to ensure that the AHJ understands the operational characteristics of the integrated systems and the fact that a fire alarm signal will not be lost with the systems that are integrated.

Thus, the fire alarm system presents certain inherent obstacles for the engineering team and the contractor. NFPA 72 allows the fire alarm system to interface with other building systems as long as the integrated system meets certain requirements. These include being certain that, when other building systems share the fire alarm system signaling-line circuits, the integrated system meets the requirements established for combination systems. Essentially, this means that the fire alarm system operation takes precedence over all other BAS. NFPA 72-2016 Section 23.8.2.6.1 also requires the following:

“ … all signal control and transport equipment (such as routers and servers) located in a critical fire alarm or emergency control function interface-device signaling path shall be listed for fire alarm service, unless the following conditions are met:

  1. The equipment meets the performance requirements of NFPA 72-2016 Section 10.3.5 (Voltage, temperature, and humidity variation requirements).
  2. The equipment is provided with primary and secondary power and monitored for integrity as required in NFPA 72-2016 Sections 10.6, 10.6.9, 10.18, and 12.6 (Power supply requirements).
  3. All programming and configurations ensure a fire alarm system actuation time as required in NFPA 72-2016 Section 10.11.1. (All alarm functions must actuate within 10 seconds after the activation of an initiating device.)
  4. System bandwidth is monitored to confirm that all communications between equipment that is critical to the operation of the fire alarm system or emergency control function interface devices take place within 10 seconds; failure shall be indicated within 200 seconds.
  5. Failure of any equipment that is critical to the operation of the fire alarm system or emergency control function interface devices is indicated at the master fire alarm control unit within 200 seconds.”

In addition, the fire alarm system must have a listed barrier gateway integral, or attached, to each fire alarm control unit or group of control units, as appropriate, to prevent the other interfaced systems from interfering with or controlling the fire alarm system. Such requirements can be difficult to comply with and sometimes even more difficult to maintain over time.

Guidelines for specifying a BAS

As with any complicated system like a BAS, the engineering team and the contractor must recognize the inherent risks. First, these types of projects cannot be specified without a good working knowledge of how the equipment will work. And the contractor should not bid these types of projects without understanding the dependence they will have on the suppliers and their technicians and programmers.

The suppliers must provide the contractor with the necessary training and technical assistance to ensure an efficient installation. And the engineering team must specify that the specified manufacturers will participate in the final acceptance testing of the integrated systems. These types of integrated systems may require negotiation with the AHJ. But the wise engineer will control substitutions and realize that buying the systems based only on price is a mistake.

By taking some practical steps, the engineering team and contractors can navigate these challenges. Due to system complexity, the engineering team should be aware of the necessary testing that is required and specify the details of the testing approach to ensure the contractors involved are aware of the detail expected for the testing process. In addition, contractors may experience additional costs due to delivery delays, extensive programming, or lengthy testing and balancing time frames. In large systems where the BAS will be integrated with the fire alarm system, the engineering team should obtain expected shipping information and guaranteed technical assistance with every manufacturer specified for the integrated systems. The contractor, on the other hand, must make sure purchase orders and agreements are written with specific guaranteed delivery schedules and a guarantee that technical assistance will be available during construction and during acceptance testing. Early in the design and construction process, the engineering team and the contractor must address the addition of the communication structure for the BAS, addressing this from a contractual and operations point of view. The engineering team should ensure that the bidders for the project are proficient enough to install and maintain the integrated systems while still meeting all code requirements. Again, a contractor cannot approach this kind of project like they do other projects.

The engineering team faces numerous challenges to ensure they understand the integrated systems operation. Contractors who intend to enter this sophisticated market face many of the same challenges. For both the engineer and the contractor, challenges include understanding diverse and complicated systems, unique communication schemes and infrastructure, and the additional, and often time-consuming, process for system testing, commissioning, and acceptance. The engineering team must both specify and participate in the commissioning of the integrated systems.

After the contractor tests the integrated systems, the engineers also must ensure that the contractor also participates in the commissioning of the individual systems in accordance with NFPA 3: Standard for Commissioning of Fire Protection and Life Safety Systems and NFPA 4: Standard for Integrated Fire Protection and Life Safety System Testing. The contractor must verify that the systems will perform together as specified. To accomplish these goals, the engineering team must ensure that the specifications provide the contractors with clear responsibilities for the implementation of the integrated systems, to avoid poor or noncomplying system performance.

After the project has been installed, the details of the integrated design must be recorded. We know it is rare for any of these integrated systems to be installed exactly as specified. That is why ensuring all of the information about the “final” integrated system is documented in accordance with Chapter 7 of NFPA 72-2016. Providing responsible and correct documentation is probably the single most important item that, when completed, will ensure ease of troubleshooting as well as ease of upgrading the integrated system in the future. NFPA 72, Chapter 7, requires that evaluation documentation include a signed statement by the person responsible for the design, attesting to the evaluation and the resultant technical decision and deeming it reliable and acceptable for the application, which means the installed integrated system is in compliance with the design specifications. And NFPA 3 requires that the evaluation documentation (commissioning information) be retained for the life of the system. The information retained must include the system operation information, which is generally in the format of an input/output matrix. An example of a matrix of operation is shown in Figure 1.

It is advisable for the engineering team to enforce the requirements of NFPA 72-2016, Section 7.5, regarding completion documents. This section should be referenced in its entirety to make sure the contractors bidding the project understand the importance of documenting the system installation. The importance of these requirements cannot be overstated. NFPA 72-2016 Section 7.5.3 requires all systems to include the following documentation, to be delivered to the owner or the owner’s representative upon final acceptance of the system:

  1. An owner’s manual and manufacturer’s published instructions covering all system equipment.
  2. Record (as-built) drawings.
  3. A completed record of the completion form.
  4. For software-based systems, a record of the site-specific software.

If the engineering team specifies these requirements upfront, there is a better chance the contractors will know that all features and components of the integrated system will need to be recorded for review. Obviously, it is important for the engineering team to assign a competent engineer to review the drawing submissions. Preferably, this engineer will be intimate with the design and will participate in the commissioning process.

As with any specialty market, success will depend on how well one understands the market and how well one plans the design process. When integrating a fire alarm system with an HVAC system or BAS, stay focused on the goal of limiting the spread of smoke with a coordinated approach to keep things simple, where possible. And when that integration involves a fire alarm and BAS interface, the engineering team must make the specifications clear in terms of both system operation and contractor responsibility. This process will help to avoid a nightmare installation by ensuring all contractors involved have a complete understanding of what is expected, allowing them to plan accordingly.


Wayne D. Moore is a vice president with the fire protection engineering and code-consulting firm JENSEN HUGHES, located in the firm’s Warwick, R.I., office. He currently serves as a member and former chairman of the NFPA 72-2016 Emergency Communications Systems (ECS) Technical Committee and is the editor/co-editor of five editions of the National Fire Alarm Code Handbook.

Larry D. Rietz is a National Institute for Certification in Engineering Technologies (NICET) Level IV-certified fire alarm designer, is the director of the JENSEN HUGHES Denver office. Rietz currently serves on the Automatic Fire Alarm Association (AFAA) Board of Directors, as a principal on the NFPA 1616 Technical Committee, and as an alternate on the NFPA 72 Chapter 24 ECS Technical Committee.