Suburban Firefighting: UL Study on Ventilation and Fire Behavior

By Jerry Knapp

In December 2010, Underwriters Laboratories (UL), under the direction of Steve Kerber, published a study entitled “Impact of Ventilation on Fire Behavior in Legacy and Contemporary Residential Construction.” The results of this study should cause you to consider changes in the way you approach the most dangerous fires we face: house fires. In this short column, we cannot even scratch the surface of this ground-breaking report, nor can we explore in detail the supporting data it contains. I urge you to go to the UL Web site and spend some time exploring this valuable research project. What we will do in this column is introduce this report to you so you can consider reviewing the strategy and tactics you use for house fire search, rescue, and fire suppression operations. This project is best described in a paragraph from the executive summary.

Under the United States Department of Homeland Security (DHS) Assistance to Firefighter Grant Program, Underwriters Laboratories examined fire service ventilation practices as well as the impact of changes in modern house geometries. There has been a steady change in the residential fire environment over the past several decades. These changes include larger homes, more open floor plans and volumes and increased synthetic fuel loads. This series of experiments examine this change in fire behavior and the impact on firefighter ventilation tactics. This fire research project developed the empirical data that is needed to quantify the fire behavior associated with these scenarios and result in immediately developing the necessary firefighting ventilation practices to reduce firefighter death and injury.

It seems to me the most pressing question of firefighter survival this report examines is this: We all know and accept the fact that house fires have changed over the past 30 years because of construction, furnishings, size, and shape of homes. So, what happens when we apply old legacy strategy and tactics to modern house fires, and why do we still do it? Additionally, we know from experience if we vent the fire building without water on the fire, we will see a dramatic increase in the fire–but how much, and how soon?  The most startling results of UL’s excellent full-scale live burns of one- and two-story homes include the following:

1. In a one-story home, firefighters have approximately (on average) 100 seconds from the time we open the front door (we never think of this as ventilation, but it is) until the place lights up and the conditions inside become untenable.

2. In a two-story home, we have approximately 200 seconds until the house becomes untenable when fire has spread from one room of fire. These numbers, of course, are based on test data, and if firefighters or occupants open other windows and doors, the times to untenability are significantly lower and less predictable.


(1) You entered the front door of this private dwelling for a search for reported victims. The living room suddenly went to flashover while you were searching. If you are surprised that this happened, it is likely you will die here. Your turnout gear is saturated with heat, simply passing that heat on to your skin. The 2,000ºF heat of the fire easily burns your skin when it reaches around 124ºF. Painful burns make rational thoughts impossible. We must understand the deadly house fire to ensure our survival.

Consider what happens if we apply current strategy and tactics. We arrive to find smoke venting from one or more windows and reports of people trapped in a single-family home. Current practices have us force the door and enter the home for a search. Search teams (truck company members) enter without a hoseline and conduct an aggressive and rapid primary search. In a two-story home during nighttime fires, searching the upstairs bedrooms is a priority, so we often dash up the stairs. If water is not applied with the time frames listed in the points above, the search team(s) will likely be caught in untenable conditions and will be attempting to bail out windows in a last-ditch effort to save themselves. Case histories prove that often it is luck that determines if they survive or not.

What does this mean to us on the fireground? A reasonable person could conclude the following: Assume a house fire is going to flash over, and plan for it; interior overly aggressive search tactics we know and trust may be just too dangerous to use now (under some conditions. It is absolutely critical to get decisive amounts of water on the fire to ensure the safety of our members.

Taking these thoughts a few steps further, maybe we should consider using vent-enter-search (VES) techniques as a good alternative to forcing the front door and dashing up the stairs. VES, developed and used by the Fire Department of New York, increases the safety of members by having them enter through the second-floor windows and conduct a search operation while already in an area of refuge–a bedroom with a closed door separating them from the active fire. This may be especially important in understaffed crews and departments that cannot deploy enough personnel to conduct an effective interior search-and-rescue operation and simultaneously deploy and advance a hoseline. Like everything we do on the fireground, VES is not a silver bullet and must be used based on appropriate size-up of the life hazard to occupants, life hazard to firefighters, fire situation, and fire building characteristics.

For those fortunate departments that roll out fully staffed, the benchmark of 100 and 200 seconds to flow decisive amounts of water must be made a standard operating procedure (SOP) and a constant training objective. Sure, you say, any engine company can do that, but can they really? Can they do it every time? The only way to ensure it is to make it a training objective, train to the standard, and evaluate the performance to be sure the standard is being met. Consider some of the variables firefighters must contend with when deploying hoselines–long stretches down driveways; garden apartments; cars with tires that seem to just grab hoselines; fences impeding the stretch; preconnected lines that may be short; dead loads that have to be estimated properly. Don’t forget overcoming problems such as kinks, couplings hung up on door frames or steps, and so forth. It is easy to sit in the office and say, “Hell yea, we can do that!” It is another thing to actually test it in training or on the fireground.

This has been just one little glimpse into a research project that both confirms what we already know and puts forward some good scientific data to help keep us out of the burn units. I urge you to read and study the report and compare your current SOPs to the data in the report. Firefighters’ lives depend on matching our strategy and tactics to the situation.

JERRY KNAPP is the assistant chief for the Rockland County (NY) Hazmat Team and a training officer at the Rockland County Fire Training Center in Pomona, New York. He is a 35-year veteran firefighter/EMT with the West Haverstraw (NY) Fire Department, has a degree in fire protection, and was a nationally registered paramedic. Knapp is the plans officer for the Directorate of Emergency Services at the United States Military Academy in West Point, New York.

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