Analysis of Search and Rescue Tactics in Single-Story Single-Family Homes: Part IV

Early full-scale fire service research on the residential fireground has studied the impact of suppression and ventilation tactics and their impact on fire dynamics. More recent research has started to examine the impact of firefighting tactics on victim survivability in addition to fire dynamics, including the latest release of Parts I–III of the Study of Fire Service Residential Home Size-up and Search and Rescue Operations project. The current study utilizes the same structures from the first search and rescue study to answer additional fire service questions and further bolster existing research. Each fully furnished structure included four bedrooms, two bathrooms and an open-floor kitchen and living room. The structures were instrumented to quantify post-ignition toxic and thermal conditions. Temperature, velocity, pressure, gas concentration, and heat flux were measured to evaluate both fire dynamics as well as toxic and thermal exposures to potentially trapped occupants.Five experiments examined bedroom fires, two experiments examined kitchen fires, and three experiments examined living room fires. Across this series of experiments, the impact of isolation of fire and non-fire compartments, the timing of search actions relative to suppression actions, and the influence of isolation, elevation, and path of travel during rescue were examined with respect to occupant survivability and firefighter safety. The impact of different designs for building heating, ventilation, and air conditioning (HVAC) systems was also studied.Similar to previous experiments in both purpose-built and acquired structures, the data showed that prior to intervention, locations lower in elevation and/or behind closed doors had lower toxic gas and thermal exposures compared to locations at higher elevations or locations that were not isolated. Similarly, trapped occupants in areas closer to the fire experience a higher thermal threat than occupants further away from the fire. Other dependencies include the level of which the fire is on compared to the level of the occupant, and if the occupant is isolated from the flow path. Lower elevations were also shown to have lower toxic gas and thermal exposures during the removal of occupants as part of rescue operations.For scenarios where search operations occurred prior to suppression, isolation of spaces from flow paths connected to the fire compartment was shown to be effective at reducing the thermal operating class for firefighters and the toxic and thermal exposure rates compared to spaces that were not isolated. Following isolation, exterior ventilation was found to further reduce the toxic gas and thermal exposures in the protected space. Suppression, from either interior or exterior positions, was effective at reducing the thermal operating class for searching firefighters and the rate of thermal exposure increase to occupants. Following suppression, additional exterior ventilation (local and hydraulic ventilation) increased the rate at which the inside of the structure returned to a tenable environment.