The Official Website of Dr. John H. Klote, PE - Updated June 22, 2015
Smoke is the major killer in building fires, and smoke control
provides significant protection from the threat of smoke.
Network models are computer programs capable of simulating the pressures and airflow throughout large and complex buildings. The primary purpose of network simulations is to determine if a particular smoke control system in a particular building is capable of being balanced such that it will perform as intended. A secondary purpose of network simulations is to help size smoke control fans.
Network models for smoke control and smoke movement were first developed in the late 1960s, but early network models were cumbersome. Today, network models have advanced numerical routines and sophisticated data input and output.
In network models, a building is represented by a network of nodes (or spaces), each node is at a specific temperature and pressure. Corridors, offices, rooms, and other spaces are represented by nodes. Stairwells and other shafts are modeled by a vertical series of nodes, one for each floor. Air goes through flow paths from spaces at high pressures to spaces at low pressures. These flow paths include open doorways, gaps around closed doors, open windows, and gaps around closed windows. Flow can also happen through cracks in the construction of walls, partitions, floors and roofs.
In a network model, air from the outdoors can be introduced into any space by a pressurization system. This allows simulations of pressurized stairwells, pressurized elevators, and any other type of pressurization system. Also any building space can be exhausted. This allows simulation of zoned smoke control systems where some spaces are exhausted. Pressures throughout the building and steady flows in the paths are obtained by solving the airflow network, including driving forces such as the wind, pressurization, exhaust, and the indoor-to-outdoor temperature difference.
CONTAM is a network model developed at the U.S. National Institute of Standards and Technology (NIST), and it can be downloaded from NIST at no cost. CONTAM was developed for indoor air quality applications, but it is probably the most used computer software in the world for analysis of smoke control systems that rely on pressurization. The figure to the right is a CONTAM representation of a floor of a 15 condominium story building. Of course, all the floors in a building need to be represented in CONTAM in order to simulate the pressures and flows in the building. Chapter 14 of the Handbook of Smoke Control Engineering has more information about network models including CONTAM user information specifically aimed at speeding up analysis of smoke control systems.
Many network models including CONTAM can simulate smoke flow in a building, and this feature allows these network models to be used as part of an engineering analysis of a tenability smoke control system. Chapter 19 of the Handbook of Smoke Control Engineering discusses using CONTAM for analysis of tenability systems.
The engineering analyses of pressurization smoke control systems in complex building often need to include network modeling.
The network model, CONTAM, has graphic input that speeds up data input and reduces the potential for input errors.
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