Computer fire modeling uses complex mathematical tools to analyze the fire and life safety in buildings. Modern computer fire modeling is capable of many things, including:
- Predicting fire growth & behavior
- Evaluating occupant egress
- Analyzing smoke control systems
- Predicting detector actuation time
- Providing plausible post-fire timeline of events
Fire modeling is particularly valuable when comparing the relative outcomes of two different possible scenarios. Earlier this year, the National Institute of Standards and Technology (NIST) used detailed computer fire models to determine the critical impact that the presence of wind can have in relation to the behavior of fire and safety of firefighters, even indoors. Because wind has long been recognized as a contributing factor to fire spread in wildland fires, those that fight wildland fires are trained to account for the impact of wind in their tactics. However, while wind is also recognized to impact structural firefighting, standard operating procedures have yet to be adjusted to address the hazards that can result inside a structure from wind.
At the request of the Houston Fire Department, NIST developed fire models comparing the fire dynamics (behavior) with and without the presence of wind as a contributing factor. NIST used Fire Dynamics Simulator (FDS) and Smokeview for this study. FDS is a computational fluid dynamics (CFD) model that emphasizes smoke and heat transport from fires. Smokeview is used to visualize the results of FDS. Data collected from a fatal 2009 residential fire in Texas was used in order to complete the study. The fire killed a 29-year veteran firefighter captain, as well as a probationary firefighter.
The first fire model was designed to incorporate the actual conditions firefighters faced, including the contributing factor of wind, while the second model omitted wind altogether. The model with wind indicated that the fire followed a wind-driven flow path that rapidly increased temperatures, in excess of 260 degrees Celsius, in some areas where firefighters were working. This hazardous flow path did not develop in the model where there was no wind present. As a result, the temperatures and conditions where the firefighters were working were significantly less dangerous in the scenario without wind.
According to the NIST report, the results of the fire models are a clear demonstration of the impact of wind as a contributing factor to structural fires and how rapidly it can cause changes to the thermal environment. In addition, “the simulation results emphasize the importance of including wind conditions in the scene size-up before beginning and while performing firefighting operations and adjusting tactics based on the wind conditions”. To read about this study in detail, please visit the NIST website.
These are no longer necessary:
By Jeff Harrington, CEO and Founder of Harrington Group, Inc.