Analysis of the Coordination of Suppression and Ventilation in Multi-Family Dwellings
Authors:   UL Firefighter Safety Research Institute, Stakes Keith , Stakes Keith , Bryant Julie , Dow Nick , Regan Jack , Weinschenk Craig 
Published: December 2021

The majority of the existing full-scale fire service research studied the impact of tactics on the residential fireground, specifically in single-family structures. This study builds upon prior research by conducting thirteen experiments in three-story, multi-family dwellings to quantify the impact of coordination between ventilation and suppression actions. Experiments were conducted in four, garden-style apartment buildings; each of which had two lower-level units, four first-floor units, and four second-floor units. The apartments shared a common stairwell that was enclosed for all of the experiments in this study. To examine the effectiveness of tactics in the fire apartment, common stairwell and applicable exposure apartments, four experiments were conducted in lower-level apartments, seven were conducted in first-floor apartments, and two were conducted in second-floor apartments including both bedroom and kitchen/living room fires. The fire size varied based on the amount of initial ventilation provided. The main control variables included the location of initial water application, the ventilation method, and the timing of ventilation relative to water application. The suppression tactics included interior water application, exterior water application followed by interior water application, and a combined interior and exterior water application. The ventilation tactics examined in these experiments included horizontal, vertical, positive pressure, and hydraulic ventilation. Similar to previous experiments in acquired single-family structures, there was no meaningful increase in temperature outside of fire rooms when ventilation tactics were executed in close coordination with (shortly after or shortly before) the onset of suppression. In contrast, for experiments where ventilation occurred with delayed suppression, temperature exposures increased throughout the fire apartment, and in experiments where the apartment door was left open, temperatures and carbon monoxide exposures increased throughout the common stairwell. Suppression actions, whether interior or exterior, resulted in a decrease in temperatures and gas concentrations at locations where occupants may potentially be located. The enclosed common stairwell, a unique feature of this experimental series, acted as capture of combustion products. Opening the apartment 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 for smoke movement into the stairwell, limiting the egress for potentially trapped occupants in exposure units. Tactics such as door control, positive pressure ventilation, and hydraulic ventilation which were used both simultaneous with and sequentially post-suppression were shown to limit gas flows into the stairwell. 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.