Conclusion
Smoke control systems are complex combinations of mechanical, electrical, architectural, and fire protection components. If not properly designed and managed, they can become a problem to implement and can be very costly. Further, it may be nearly impossible to get the system to properly function if there is not a close collaboration between the architect, the mechanical engineer, and the fire protection engineer.
The complexities of modern buildings have created circumstances well beyond the capabilities of classical modeling approaches. An exceptional effort is needed to make sure design teams do not break their budget while creating an effective system that is functional, robust, and approvable.
| DOS AND DO NOTS |
|
Do involve the project stakeholders as early in the process as possible.
This should include the architect, owner, fire protection engineer/life safety consultant, mechanical/electrical engineer, and contractor. It is important for the mechanical engineer and fire protection engineer to work in concert. Perhaps most importantly, the authority having jurisdiction (AHJ) should be involved at the appropriate time, especially if computer modeling will be utilized. Presenting a Fire Engineering Design Brief that summarizes the proposed smoke control approach, types of modeling, number/nature of design fire scenarios, expected model outputs, and pass/fail criteria can go a long way in establishing a positive relationship and avoiding surprise requirements/requests after all the modeling has been completed.
Do choose a smoke control approach appropriate for the application.
This author was retained during construction of a project where the contractor was attempting to achieve a pressure differential between two large-volume spaces. The pressurization method was the wrong approach for this building, and achieving the pressures proved unfeasible. One should involve a fire protection engineer or smoke-control-savvy mechanical engineer and create the right game plan from the beginning.
Do not spend a lot of time creating complex computer models too early in the design process.
The design will change. Programming will be updated. Horizontal openings will move, grow, and multiply. One should hold on the computer modeling until the schematic design is finalized. A relatively stable BIM model can be used to import the geometry into a fire modeling program instead of building it painstakingly by hand.
Do use defendable and appropriate design fire scenarios.
National Fire Protection Association (NFPA) 101, Life Safety Code, lists eight scenarios that are required to be considered for performance-based design. Along with design fire locations, the maximum size and characteristics of the design fire are important. Just because fire test data may be available for a burning chair, is that a severe-case fire for the space in question? Documentation of these assumptions and inputs tie in to the aforementioned Fire Engineering Design Brief to be presented to the AHJ early on for its buy-in.
Do not put all the exhaust in one place.
Even if the exhaust volume satisfies the hand calculations, providing all 200,000 cfm in one corner of the atrium will probably not be effective for a design fire in distant locations. Firstly, concentrated exhaust can create plugholing, where the exhaust is so strong it pulls fresh air in through the smoke layer and therefore renders the system useless. Secondly, if smoke is required to be pulled long distances across a ceiling, it entrains more air and creates more smoke, so the original design exhaust volume may prove inadequate. Distribute exhaust inlet locations as broadly as possible to create an even exhaust scheme. Computational fluid dynamics (CFD) modeling illuminates these issues.
Do look and plan ahead for the testing and inspection process.
If possible engage the commissioning agent during the design phase to coordinate and communicate the design of the system, establishing a commissioning plan in the process. It is important to define not only what is being tested, but also the schedule, order, and the pass/fail criteria.
|
Brian Kuhn Jr., PE, LEED Green Associate, is a fire protection engineer and life safety consultant with Simpson Gumpertz & Heger based in the firm’s Boston headquarters. His primary interests and capabilities are in the fields of computer fire, smoke and egress modeling, structural fire protection, and code consulting for various occupancies. Kuhn works with architects, structural engineers, and building scientists on a variety of fire and life safety building performance issues. He has a master’s degree in fire protection engineering and a bachelor’s degree in mechanical engineering, both from Worcester Polytechnic Institute. He can be reached via e-mail at bdkuhn@sgh.com.
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.
Thanks for this article. your insights of the requirement of smoke control system for underground carpark less than 9.m, is it required or not? and will the ventilation system be adequate.