Performance-Based vs. Prescriptive-Based Criteria in Building Design: Impact on Fire Alarm Systems

Steven Forrester, P.Eng Building Code Consultant, Valfor

As building code consultants, we often work at the intersection of performance-based and prescriptive-based design criteria in compliance with the National Building Code of Canada (NBC). These two approaches can have influence on how fire alarm systems are designed and implemented, impacting the work of fire alarm technicians who handle fire alarm installation, inspection, and testing.

Prescriptive-Based Criteria (Division B)

Prescriptive-based design, outlined in Division B of the NBC, provides detailed and specific requirements for fire protection systems, including fire alarm design. This approach simplifies decision-making for both engineers and fire alarm technicians by giving clear instructions for system components, their installation, and operational parameters.

For fire alarm technicians, prescriptive-based design thus offers a straightforward process. Compliance is achieved by following prescribed rules, such as the mandatory spacing of detectors, audibility levels, and system integration with other life safety features. Inspections and testing are then able to focus on ensuring that these predefined requirements are met, which reduces uncertainty but may also limit design flexibility.

Performance-Based Criteria (Division A)

Performance-based design, as described in Division A of the NBC, focuses on achieving specific safety goals without prescribing exact methods. This approach provides an opportunity for innovative design, but requires a more in depth understanding of fire dynamics, human behavior, and system integration, to meet the NBC’s performance objectives.

Fire alarm systems designed under performance-based criteria often need to account for variables such as building geometry, fuel loads, and occupant characteristics. This means that fire alarm technicians may find it helpful to consult with designers to better understand the rationale behind fire alarm system/device placements and performance targets. Inspections and testing in this scenario could involve verifying that the system meets the defined performance objectives, which might require more complex and/or customized testing methods compared to prescriptive designs.

Preparing for Alternative Solutions

When working on buildings that include alternative solutions, fire alarm technicians can benefit from preparation that enhances their understanding of performance-based designs. An alternative solution is an approach that deviates from the prescriptive requirements of the code but still meets the NBC defined safety objectives through different means. There are several steps that technicians might consider to better equip themselves for these scenarios:

  1. Develop Knowledge of Fire Dynamics and Human Behavior: Performance-based design is often based on how fire behaves and how people react during emergencies. Fire alarm technicians can explore opportunities to learn the principles of fire behavior, smoke movement, and evacuation modeling. Familiarity with these concepts can help technicians appreciate why specific fire alarm system designs are used in performance-based solutions.
  2. Collaborate Early with Designers: Participating in the design process can help fire alarm technicians understand the specific goals of the performance-based design. By doing so, technicians can stay informed about unique system features or integrations with other fire protection systems, and can better anticipate potential challenges during installation or testing.
  3. Stay Updated on Building Codes and Standards: Keeping up with the prescriptive requirements of NBC’s Division B can be beneficial for fire alarm technicians. Understanding how various fire alarm technologies support innovative designs (i.e., voice communication and smoke management systems) can better ensure that technicians are prepared to implement and test these advanced systems effectively.
  4. Enhance Skills in Integrated Testing: Performance-based designs regularly rely on the collaboration of multiple fire protection systems. Fire alarm systems frequently communicate with, but not limited to, sprinklers, smoke control systems, and HVAC systems to meet performance objectives. Fire alarm technicians should find value in developing proficiency in conducting integrated tests, ensuring that all systems work together to achieve the desired level of fire safety.
  5. Consider Specialized Certifications and Training: Pursuing additional certifications or training related to performance-based fire protection strategies would offer fire alarm technicians additional expertise that could come in handy when working with alternative solutions.

Examples of Fire Alarm Integration in Fire Protection-Based Alternative Solutions

As previously mentioned, fire alarm systems are integral to many fire protection-based alternative solutions. Below are some examples where fire alarm systems play a critical role in supporting these strategies:

  1. Smoke Control Systems: In high-rise buildings or large open spaces, smoke control systems can be used to maintain tenable conditions for occupants during evacuation. These systems often rely on fire alarm activation to control smoke dampers, fans, and other mechanical equipment. In a performance-based design, a smoke control system could serve as an alternative to traditional fire compartmentation (i.e., permit the omission of fire separations that would otherwise be required). Fire alarm systems in these examples would need to be integrated with smoke control mechanisms to ensure they function as required during a fire.
  2. Voice Communication Systems for Emergency Evacuation: Some performance-based designs in complex buildings may use voice communication systems to provide real-time evacuation instructions, instead of relying solely on alarms and strobes. Fire alarm technicians involved in these projects could be tasked with installing and testing voice communication systems, ensuring their integration with the fire alarm system is operational.
  3. Fire Suppression System Integration: Certain performance-based designs incorporate specialized fire suppression systems, such as gaseous or foam-based suppression, particularly in environments like data centers or industrial facilities. Fire alarm systems are regularly used to detect early fire conditions and trigger the noted suppression systems. In such instances, fire alarm technicians play a key role in ensuring that the detection and suppression systems are properly integrated and operate as per the intended fire protection strategy.
  4. Customized Detector Placement in Atriums: Atriums can present unique fire safety challenges, particularly in managing smoke and facilitating occupant egress. Performance-based designs for atriums may propose alternative solutions for smoke management, which could include placing smoke detectors in non-typical locations. Fire alarm technicians working in these scenarios would benefit from understanding of how these detector placements contribute to the overall fire protection strategy and their intended function.

The Importance of Integrated Testing in Performance-Based Designs

As identified throughout this article, integrated testing is often a critical step in verifying that performance-based fire protection systems achieve the required safety outcomes. This testing evaluates how well multiple systems, including but not limited to fire alarms, sprinklers, smoke control, and emergency communication systems, work together.

For fire alarm technicians, integrated testing in performance-based designs can extend beyond the standard functional tests of prescriptive systems. These tests often involve simulating fire scenarios to observe how a fire alarm system interacts with other safety systems, ensuring that the overall performance objectives are met. For example, fire alarm technicians might be required to perform scenario-based tests, such as simulating a fire in an atrium to verify that the fire alarm system activates the smoke control system as designed.

Additionally, integrated testing may involve real-time fire drills that replicate actual fire conditions. This type of testing allows fire alarm technicians to confirm that the fire alarm system, along with other systems, can manage the potentially complex fire safety strategies outlined in the performance-based design.

Conclusion

As new building technologies emerge and the scope of performance-based design opportunities continues to broaden, fire alarm technicians can anticipate working on unique fire protection strategies. The flexibility of performance-based designs provide more room for innovation, while commonly demanding a higher level of understanding and preparation from fire alarm technicians. By staying informed about both prescriptive and performance-based code requirements, developing collaborative relationships with design teams, and honing skills in integrated testing, technicians can be better equipped to navigate the evolving landscape of fire alarm system design and compliance.

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