Smoke control: Getting it right

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The International Building Code (IBC) calls for smoke control for several high-risk building conditions, including large-volume spaces like shopping malls, where many occupants may be exposed to the effects of fire.

Other system requirements
Proper documentation for the system is not only best practice, but also required by code. IBC Section 909 mandates a smoke control rational analysis accompany the project construction documents. The rational analysis is required to justify the smoke control systems to be employed, the method of operations, and the system equipment. The analysis must also cover the following topics:

  • stack effect;
  • temperature effect on fire;
  • wind effect;
  • HVAC systems;
  • climate; and
  • duration of operation.

A well-prepared rational analysis documents the basis of design. This document goes a long way toward achieving approval from the AHJ, facilitating and organizing the commissioning process, and participating in a potential third-party review. The report will be used by the design team, the contractor, the commissioning agent, and building inspectors. The absence of thorough documentation can lead to problems during construction, project delays, and cost overruns; it also creates a risk regarding life safety.

Other code requirements need to be considered during project planning. While this is not an exhaustive list, some considerations include:

  • whether the smoke control system will be operated by the fire alarm system or by the building management system (BMS)—both are allowed, but the control system needs to be UUKL listed under ANSI/UL 864, Standard for Control Units and Accessories for Fire Alarm Systems;
  • a firefighter’s smoke control station (FSCS) or smoke control panel (FFSCP) is required in the fire command center or an approved location;
  • the smoke control panel must include manual control or override of automatic control for smoke control system functions, including fans and dampers, operable doors, and vents;
  • the smoke control panel must have positive status indicators for all smoke control equipment.
  • smoke control systems need to be on standby power, with controls relying on volatile memories (control panels) supplied with uninterruptible power sources capable of spanning 15-minute primary power interruption;
  • equipment (e.g. ducts, fans, and dampers) must be listed and must be capable of withstanding the probable temperatures and pressures to which they will be exposed;
  • belt-driven fans are required to have 1.5 times the number of belts required for the design (the minimum is two); and
  • all wiring is required to be fully enclosed within continuous raceways.

Commissioning
After the system has been designed, it needs to be built correctly and approved. Commissioning is an integral part of the design and implementation process. This article presents only a brief overview of the commissioning process, which is an involved project in its own right. NFPA 3, Recommended Practice for Commissioning and Integrated Testing of Fire Protection and Life Safety Systems, was developed and introduced in 2012 to assist project teams with the process.

Commissioning actually starts during design. The commissioning team needs to be identified early, and it should include the owner or owner’s representative, the registered design professional (RDP) for the system, the commissioning agent (CxA), the third-party testing entity, the construction manager, and, ideally, the AHJ. Documents need to be produced including the basis of design (rational analysis) discussed earlier, a written commissioning plan including commissioning schedule, and the associated drawings and specifications for the system. When the CxA has been involved in the development of the commissioning plan, the whole process goes smoother.

In addition to the mechanical system tests that may come to mind when one thinks of smoke control testing, some of the commissioning begins earlier in construction. Duct pressure testing is usually done before the ducts are closed-in so the contractor can fix any deficient conditions noted during the test. Large systems should have inspections throughout the construction phase to look at the installation of dampers and fans so issues like reversed dampers are identified before the walls are completed.

Codes require the control wiring of the smoke control system to be enclosed in raceways. It should be noted this includes fire detection wiring for devices that initiate the smoke control system, and BMS wiring if the BMS system manages the smoke control. Architectural features requiring inspection include shaft integrity, firestopping, doors and closers, glazing, and smoke partitions.

Prior to acceptance testing with the AHJ, several rounds of operational testing should be performed to ensure all functions in the sequence of operations perform properly. This is where the commissioning team needs to work thoroughly, diligently, and effectively to prepare for final inspections. With the right effort and attention to detail, the approval testing should simply be a demonstration that the system functions as the commissioning team intended.

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One comment on “Smoke control: Getting it right”

  1. It’s great that you’ve mentioned how an effective smoke control system design requires the involvement of a fire protection engineer from the beginning so that everything can be done correctly. I’ve heard that our office wants to improve its emergency measures in case of fire, and what came to their minds would be to get a smoke control system. I will mention this to them so that they can consult the services of a fire protection engineer or other experts on this matter so that the job will be done correctly.

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