Analysis of the Coordination of Suppression and Ventilation in Single-Family Homes
Authors:   UL Firefighter Safety Research Institute, Regan Jack , Bryant Julie , Weinschenk Craig 
Published: December 2021

Prior full-scale research with the fire service was primarily designed to isolate specific tactics, most often either ventilation or suppression, which allowed researchers to develop science-based recommendations related to the specific components of fireground operations studied in relatively controlled conditions. The current project went beyond earlier research by conducting twenty experiments in eight acquired, single-family residential structures and that combined fireground tactics to quantify the impact of coordination between ventilation and suppression actions. This experimental series included second-story bedroom fires (14 experiments) and first-floor kitchen fires (6 experiments). The main control variables studied included the position of initial application of water, the ventilation method, and the timing of ventilation relative to water application. The ventilation tactics examined in these experiments included horizontal, vertical, positive pressure, and hydraulic ventilation, while the suppression tactics included both interior water application and initial exterior water application followed by interior water application. While some elements of the experiments (e.g. structure floor plan and weather) resulted in increased variability, the lessons learned highlighted the importance of having a systematic approach to the implementation of tactics. Most importantly, there was no meaningful increase in temperature outside of fire rooms when ventilation tactics were executed in coordination with (shortly after or shortly before) the onset of suppression. The effectiveness of suppression actions in extinguishing the fire were dependent on the ability of those actions to 1) cool surfaces in the fire room and 2) wet unburned fuel. Exterior suppression actions on second-floor bedroom fires resulted in a decrease in temperatures throughout the second floor, followed by regrowth prior to final suppression through interior streams. When exterior suppression was performed on first-floor kitchen fires, where more complete fuel wetting was possible, regrowth was not observed prior to interior suppression. When surface cooling or fuel wetting are not possible due to the elevation of the fire room, missing ceiling, or obstacles, firefighters should consider alternative means of water distribution to improve the effectiveness of suppression actions from outside the fire room. Suppression actions, whether interior or exterior, generally resulted in a decrease in temperatures and gas concentrations at locations where occupants may potentially be located. Conditions improved most quickly at locations closest in proximity to the inlet of the flow path established between the front door and the fire room. For this reason, opening an exterior door to gain access should be thought of as an important ventilation action, both in terms of its potential to cause fire growth and its potential to improve conditions for potentially trapped occupants. After effective suppression, structure ventilation operations should similarly be cognizant of gas flows, with the aim of establishing flow throughout all areas where occupants may be located.