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February 13, 2021
Stairwell and elevator pressurization systems are essential to life safety. But how can you know whether your systems are up to code and providing adequate life safety? In this blog, we look at how to analyze stairwell and elevator pressurization using CONTAM.
There are a couple of ways to analyze pressurized stairwells, pressurized elevator hoistways, and smoke control systems for protected corridors and egress paths. However, the most appropriate approach in order to ensure project success, implementation and acceptance is through a computational network model such as CONTAM.
CONTAM is a building airflow and contaminant dispersal model developed by the National Institute of Standards and Technology (NIST). CONTAM analyses are an approved method for analyzing and sizing smoke control systems as recognized by NFPA 92, Standard for Smoke Control Systems, as referenced by the IBC.
CONTAM is the preferred approach to perform a complete analysis of the interactions between multiple smoke control systems operating in a building, or simply one system’s interactions with key building components. This is because general rules of thumb and algebraic equations may not be appropriate once multiple systems are incorporated into a design, or unique building features such as a stairwell door open to the exterior or communicating spaces.
Fire protection engineers utilize CONTAM for two main purposes. The first is to determine what specific smoke control system design will be appropriate to achieve the intended design conditions for each system evaluated (i.e. ground floor lobbies, external vent, simple system). Once an appropriate method is determined, the final capacities of supply and exhaust fans and locations can be determined through an iterative modeling approach, taking into account sensitivity evaluations such as variance in external temperatures, wind and building construction.
A CONTAM model can greatly assist your design team by ensuring that all aspects of a smoke control system operate as intended and meet design criteria. Effects that one system has on another, such as the difficulty in balancing stairwell pressurization with an elevator pressurization system, can be accounted for in the model.
In addition, further analysis can be conducted on atrium smoke control systems, coupling results from a fire dynamics simulator (FDS) or other computational fluid dynamics (CFD) model into CONTAM to examine the impact that this additional system could have on stair pressurization. These models can greatly assist your team in providing a compliant smoke control system for your project, making the acceptance and commissioning of the systems significantly smoother.
In order to analyze your stairwell and elevator pressurization systems, you need a fire protection engineer who has hands-on experience with CONTAM modeling services. That way, you can determine whether your building has the appropriate design to keep your occupants safe. Using this approach mitigates the stories of failed testing causing days or weeks of commissioning.
In a project that received national headlines, it appears that CONTAM or a more scientific approach was not utilized to size and evaluate the smoke control systems at the University of Wisconsin-Madison. This resulted in a significant delay in the building opening, additional cost implications and an inconvenience to the university.
Performance Based Fire can provide CONTAM modeling services for your project in a timely and cost-effective manner. Contact us to learn more about this service offering.
