Wind Driven Fires

Wind blowing into the broken window of a room on fire can turn a “routine room and contents fire” into a floor-to-ceiling firestorm. Historically, this has led to a significant number of firefighter fatalities and injuries, particularly in high-rise buildings where the fire must be fought from the interior of the structure.

Wind-Driven Fire in a Ranch-Style House in Texas, 2009

On April 12, 2009, a fire in a one-story ranch home in Texas claimed the lives of two fire fighters. (NIOSH REPORT HERE) Sustained high winds occurred during the incident. The winds caused a rapid change in the dynamics of the fire after the failure of a large section of glass in the rear of the house.

Wind Driven Fire in Home, Texas, 2009. Aerial view of damage to the structure. Photo credit: Houston Fire Department.

NIST performed computer simulations of the fire using the Fire Dynamic Simulator (FDS) and Smokeview, a visualization tool, to provide insight on the fire development and thermal conditions that may have existed in the residence during the fire.

The FDS simulation that best represents the witnessed fire conditions indicates that the fire that spread throughout the attic and first floor developed a wind driven flow with temperatures in excess of 260 °C (500 °F) between the den and front door. The critical event in this fire was the creation of a wind-driven flow path between the upwind side of the structure and the exit point on the downwind side of the structure, the front door. The flow path was created by the failure of a large span of windows in the den, in the rear of the structure. Floor-to-ceiling temperatures rapidly increased in the flow path where multiple crews were performing interior operations. In a simulation that excluded wind, the flow path was not created, and the thermal environment surrounding the location of interior operations was improved.

Still image from FDS simulation. Temperatures at 1.5 m (5 ft) above the floor throughout the house 10 s after solarium failure. Image credit: NIST.

Wind has been recognized as a contributing factor to fire spread in wildland fires and large-area conflagrations and wildland fire fighters are trained to account for the wind in their tactics. While structural fire departments have recognized the impact of wind on fires, in general, the standard operating guidelines for structural fire fighting have not changed to address the hazards created by a wind driven fire inside a structure. The results of the “no-wind” and “wind” fire simulations demonstrate how wind conditions can rapidly change the thermal environment from tenable to untenable for fire fighters working in a single-story residential structure fire.

The simulation results emphasize the importance of including wind conditions in the scene size-up before beginning and while performing fire fighting operations and adjusting tactics based on the wind conditions. These results are in agreement with NIST studies conducted to examine wind driven fire conditions in high-rise structures.

LESSONS LEARNED

Based on the analysis of this fire incident and results from previous studies, adjusting fire fighting tactics to account for wind conditions in structural fire fighting is critical to enhancing the safety and the effectiveness of fire fighters. Previous studies demonstrated that applying water from the exterior, into the upwind side of the structure can have a significant impact on controlling the fire prior to beginning interior operations. It should be made clear that in a wind-driven fire, it is most important to use the wind to your advantage and attack the fire from the upwind side of the structure, especially if the upwind side is the burned side. Interior operations need to be aware of potentially rapidly changing conditions.

See full report, Simulation of the Dynamics of a Wind-Driven Fire in a Ranch-Style House – Texas (NIST TN 1729, January 2012)

F2009-11

Apr 12, 2009

Career probationary fire fighter and captain die as a result of rapid fire progression in a wind-driven residential structure fire – Texas

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Career Probationary Fire Fighter and Captain Die as a Result of Rapid Fire Progression in a Wind-Driven Residential Structure Fire – Texas

SUMMARY

Shortly after midnight on Sunday, April 12, 2009, a 30-year old male career probationary fire fighter and a 50-year old male career captain were killed when they were trapped by rapid fire progression in a wind-driven residential structure fire. The victims were members of the first arriving company and initiated fast attack offensive interior operations through the front entrance. Less than six minutes after arriving on-scene, the victims became disoriented as high winds pushed the rapidly growing fire through the den and living room areas where interior crews were operating. Seven other fire fighters were driven from the structure but the two victims were unable to escape. Rescue operations were immediately initiated but had to be suspended as conditions deteriorated. The victims were located and removed from the structure approximately 40 minutes after they arrived on location.

Key contributing factors identified in this investigation include: an inadequate size-up prior to committing to tactical operations; lack of understanding of fire behavior and fire dynamics; fire in a void space burning in a ventilation controlled regime; high winds; uncoordinated tactical operations, in particular fire control and tactical ventilation; failure to protect the means of egress with a backup hose line; inadequate fireground communications; and failure to react appropriately to deteriorating conditions.

NIOSH investigators concluded that, to minimize the risk of similar occurrences, fire departments should:

• ensure that an adequate initial size-up and risk assessment of the incident scene is conducted before beginning interior fire fighting operations
• ensure that fire fighters and officers have a sound understanding of fire behavior and the ability to recognize indicators of fire development and the potential for extreme fire behavior (such as smoke color, velocity, density, visible fire, heat)
• ensure that fire fighters are trained to recognize the potential impact of windy conditions on fire behavior and implement appropriate tactics to mitigate the potential hazards of wind-driven fire
• ensure that fire fighters understand the influence of ventilation on fire behavior and effectively apply ventilation and fire control tactics in a coordinated manner
• ensure that fire fighters and officers understand the capabilities and limitations of thermal imaging cameras (TIC) and that a TIC is used as part of the size-up process
• ensure that fire fighters are trained to check for fire in overhead voids upon entry and as charged hoselines are advanced
• develop, implement and enforce a detailed Mayday Doctrine to insure that fire fighters can effectively declare a Mayday
• ensure fire fighters are trained in fireground survival procedures
• ensure all fire fighters on the fire ground are equipped with radios capable of communicating with the Incident Commander and Dispatch

Additionally, research and standard setting organizations should:

• conduct research to more fully characterize the thermal performance of self-contained breathing apparatus (SCBA) facepiece lens materials and other personal protective equipment (PPE) components to ensure SCBA and PPE provide an appropriate level of protection.
• Although there is no evidence that the following recommendation could have specifically prevented the fatalities, NIOSH investigators recommend that fire departments:
• ensure that all fire fighters recognize the capabilities and limitations of their personal protective equipment when operating in high temperature environments.