The Burn Building Limits

The number of structure fires that each individual firefighter is able to experience continues to decrease. According to the National Fire Protection Association, there were 573,500 fires in 1995, 511,000 in 2005, and 475,500 in 2016. Couple that with the fact most organizations do not participate in acquired structure burns anymore (see “The Acquired Structure Training Effect,” FireRescue, June 2017), and you have a real dilemma trying to create realistic experience.

There are only a couple types of burn buildings being used today, and each jurisdiction makes selections based on a host of variables—one of the most notable being cost. I want to encourage the decision makers to put mission as the number one factor when determining what type of burn building to invest in. In other words, what is it that you are trying to accomplish with the burn building? In previous decades that mission may have been different than what it is or what it needs to be now. With a higher number of actual structure fire responses and the use of acquired structure live burns, many burn buildings were built only to provide a place that reduced the logistical requirements of having to rely on acquired structures, provide a multiuse building that was in the control of the department to be used any time needed, and serve as a place to practice the tactics involved in firefighting.

Types of Burn Buildings

Class B burn buildings use gas-fed props and artificial smoke to provide a very controlled environment that can be logistically managed with a very small staff. In the hands of an experienced instructor who understands fire behavior, water application, and ventilation, these props can provide a great setting for getting in those initial repetitions on interior attacks. They are, however, limited to the scenarios that the props were designed for and, let’s face it, the heat, flow paths, and other realistic components are missing. It is my opinion, based on experiences with these types of buildings, that, in the hands of very experienced instructors (experienced in real fires, that is), they are very useful in the initial basic firefighter courses and provide easily repeatable and safe fire simulations with minimal staff. However, they are extremely expensive to build and to maintain. I can’t count the number of them I have seen across the country that no longer function because no one planned for the upkeep and maintenance of these complex systems. Many have now been converted to “smoke houses” with no live fire component, and some have been converted to use as Class A buildings.

Class A buildings are typically built for instructors to build fires in designated areas. The standard fire load is wood pallets, either straw, hay, or excelsior. These buildings get better marks in being able to create heat and flow paths. However, they do not provide realistic fires that require substantial fire flow to knock down or extinguish. Instructors are known to have students open the nozzle and quickly shut it down so that the fire and bed of coals are not extinguished. This is done so that the next fire is quickly set and the conditions are ready for the next group to rotate in. For inexperienced firefighters, the actions they take stick with them no matter how many times the instructor says, “Now you would really flow more water if this was in a real structure.” Time and time again, we see firefighters flowing little blasts of water when they need to open that nozzle up and overwhelm the environment with the heat absorbing effects of gallons per minute.

While the conditions in these structures are more realistic with regard to heat, smoke, and flow path, the fire itself doesn’t spread, rarely are gases burning, and the water flow needed to improve conditions is very minimal. For the purpose of this discussion, I am including the “Flashover Chamber” in my classification of Class A burn buildings.

Several training groups and organizations do use Class A buildings with wall and ceiling build outs that allow for hidden fire, the need for overhaul, and all the other work that comes along with a real fire. The use of oriented strand board in fuel packages and the use of low flow nozzles are helping to create a better realistic experience—but there are still limitations.

In both the Class A and B buildings, one of the most unrealistic tactics practiced is that of ventilation. These limited fuel packages or gas-fed fires don’t pack the energy of a real house fire and rarely reach the ventilation limited stage unless special fire loading, construction, and fuel packages are used. In the majority of these burn building fires, ventilation of any type is always successful at releasing the heat without leading to any problems. Because the fires are not ventilation limited or oxygen deprived, there is no problem. If we luck up and get to a real fire that is not ventilation limited, then the tactics we practiced work fine. However, our members may not recognize when the conditions are not like those in the burn building. Again, we remember what worked the last time we were in a similar situation. For many, that similar situation is that they are both fires. If we are only pulling from the slide tray of burn building fires, our members don’t fully understand the real effects and when and how to coordinate ventilation with fire attack. The role of a competent, up-to-date instructor cannot be emphasized enough for these training buildings.

Understanding the Limits

Understanding the limits of these buildings is critical to both fire service leaders and instructors. Many fireground problems experienced by departments can be traced back to a lack of understanding of these limitations. In the absence of real fire experience, the instructors naturally begin teaching from their actual experiences, which may be limited to primarily the fires in these Class A and B burn buildings. Tactics begin to be discussed and tested in these buildings. Soon, we find we have unintentionally started to adapt our older tactics and take some shortcuts that make it easier for us to operate in our artificial environment.

Burn buildings and flashover chambers are a great place to practice the mechanics and get repetitions in for fire behavior and tactics training. They are NOT the place to develop the tactics. The conditions created by fires in either type of burn building are not realistic compared to what the firefighter will encounter in the field, and they should only be used as a tool to create “live fire simulations” that allow for some visual stimulation and the opportunity to master hose stretches, coordinate between units, and rehearse through the steps that must be taken to deploy our resources. Over the years, several tactics developed in burn buildings have swept through the fire service only to dissipate after being attempted at real fires with REALLY different results. Why? Because the variables in actual structures are not present in burn buildings. The fire behaves differently because of the type of construction and the fuel load. As instructors, we need to create conditions to mimic the real fire environment as closely as possible and we need to get creative to develop special effects that cause it to at least look like it is supposed to. This is important to building visual cues for the student to recall when needed later.

The Future

Research is currently underway to compare burn building fire environments with actual data captured in acquired structural burns. This research will hopefully lead to new designs, fuel packages, and technology that will lead to better live fire training for our members—training that will add more realistic conditions while balancing safety and exposure. The answers we seek may require a level of creativity and outside technological influence the likes of which we haven’t seen yet. In the meantime, work on the basics, have discussions with your instructors about what you are actually accomplishing in your burn buildings, and continue to practice established tactics without trying to develop new tactics there.

By David Rhodes

David Rhodes is a 32-year fire service veteran. He is a chief elder for the Georgia Smoke Diver Program, a member of the Fire Department Instructors Conference (FDIC) International Executive Advisory Board, a hands-on training coordinator for FDIC, an editorial advisor for Fire Engineering and the UL Firefighter Safety Research Institute, and an adjunct instructor for the Georgia Fire Academy. He is a Type III incident commander for the Georgia Emergency Management-Metro Atlanta All Hazards Incident Management Team and is a task force leader for the Georgia Search and Rescue Team. He is president of Rhodes Consultants, Inc., which provides public safety training, consulting, and promotional assessment centers.

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February 2018
Volume 13, Issue 2