Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction
Under the United States Department of Homeland Security (DHS) Assistance to Firefighter Grant Program, the Study of Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction (Horizontal Ventilation) examines fire service ventilation practices and the impact changes in modern home geometries have upon fire behavior. Through this research, needed empirical data is developed to quantify the fire behavior associated with these scenarios and develop practices to reduce firefighter injury and death.
Two houses are constructed in UL’s large fire facility in Northbrook, IL. The first is a one-story, 1200 ft2, 3 bedroom, 1 bathroom house with 8 rooms. The second is a two-story 3200 ft2, 4 bedroom, 2.5 bathroom house with 12 total rooms, and features a modern open floor plan, two-story great room and open foyer. Fifteen experiments are conducted varying the ventilation locations and the number of ventilation openings. This includes ventilating the front door only, opening the front door and a window near and remote from the seat of the fire, opening a window only, and ventilating a higher opening. One scenario in each house is conducted in triplicate to examine repeatability.
The results of these experiments enable the fire service to examine and update current thought processes, tactics, standard operating procedures and training content.
There has been a steady change in the residential fire environment over the last several decades, including larger homes, open floor plans and increased synthetic fuel loads.
These experiments provided significant insight into the impact of the modern fire environment and ventilation practices on fire behavior. The results have been translated into tactical considerations for the fire service.
The three key findings that drove the tactical considerations are:
- Number of Ventilation Openings: The amount of air and the location that the air supplied to a ventilation-limited fire changes how much energy a fire generates and how fast it generates it.
- Location of Ventilation Openings: Ventilating remote from the seat can increase the potential for spread the fire to uninvolved parts of the house by creating a flow path (and source of air) between the fire and the ventilation opening.
- Height of Ventilation Openings: One must also consider how the cool air enters the room as the hot gases are leaving the room. In a ventilation-limited fire, the available fuel needs the air entering the room to transition to flashover. Post-flashover, the burning will take place at the ventilation locations, leaving the room fully involved in flames
The tactical considerations provide guidance on the proper use of ventilation as a firefighting tactic to mitigate the risk of firefighter injury and death associated with improper ventilation practices.