In the world of firefighting, knowledge and tactics are always evolving, and the importance of staying informed cannot be overstated. The task of ventilation (horizontal and vertical) in residential structures has seen significant advancements through extensive research conducted by the UL Fire Safety Research Institute (FSRI). This research has shed light on the intricacies of ventilation and its profound impact on fire dynamics.
While the core task of ventilation remains largely unchanged, our understanding of when, where, and how to perform ventilation has undergone a transformation. We now have a comprehensive grasp of both the positive and negative effects of ventilation on fire incidents.
Historical Perspective
In the past, firefighters learned to prioritize early and frequent ventilation, with the belief that more ventilation is always better. These practices were largely based on anecdotal experience and lacked a solid foundation in scientific data. Fire service members were left without a clear understanding of the actual impact of ventilation on fire dynamics.
The fire service’s ongoing evolution relies on scientific insights to enhance our understanding on the fireground. One of the crucial shifts in our comprehension of ventilation is the realization that it does not equate to cooling, as previously believed. This misconception was rooted in two primary assumptions: first, that vertical ventilation lifts the neutral plane, and second, that ventilation creates a cooling effect due to the influx of fresh air into the building.
However, modern research contradicts these assumptions, revealing that ventilation primarily fuels the fire. This actually leads to increased temperatures. This misconception was also rooted in our experience. We have all been in a position and called for vertical ventilation. Once the “lift” began, we felt the “relief” or cooling of the environment. This lift, as we call it, is actually a greater influx of air providing for the misconception of relief or cooling.
Figure 1. Placement of Vertical Vent Hole: Pre-Vertical Vent
Pre-Vertical Vent
- Bi-directional flow at the front door and in the flow path to the fire.
- Heat may prevent engine from advancing if proper mapping is not possible.
(Source: All figures courtesy of UL-FSRI.)
Figure 2. Placement of Vertical Vent Hole: Temporarily Post-Vertical Vent
- Bi-directional flow at the front door can become mostly intake.
- Temporary lift may allow engine to advance for proper mapping.
- Improvement limited to flow path (not remote spaces).
Figure 3. Placement of Vertical Vent Hole: Post-Vertical Vent
- Without proper mapping, flow path may return to bi-directional.
- Fire will grow and move in flow path to firefighter location.
Today, with the clearer understanding of flow paths, it is easier to understand why this misconception existed—thus, the phrase “ventilation does not equal cooling.”
The Catalyst: UL FSRI
The pivotal turning point in our understanding of ventilation came through research conducted by the UL FSRI. Its groundbreaking technical report, titled Study of the Effectiveness of Fire Service Vertical Ventilation and Suppression Tactics in Single Family Homes, played a pivotal role in reshaping our approach to ventilation. This research has been consistently validated through various studies and live fire tests, including collaborations with the Fire Department of New York (FDNY) on Governors Island.
Coordination: The Key to Effective Ventilation
The primary objective of ventilation is to control a building’s behavior. This increases firefighter safety and creates a safer environment for potential victims. Door control plays a pivotal role in this process as well, keeping the fire in a ventilation-limited state until firefighters are ready to proceed. Effective coordination between ventilation and fire attack is essential. Here are a few pointers for the ventilation crew to follow:
- Make sure the charged hoseline is in place.
- Check to confirm the entry door is unlocked/forced but controlled in the closed position.
- Be ready to create an opening.
Controlling the door limits the fresh air available to the fire, reducing the flow path. This door control is a critical component of coordinated ventilation and fire attack. Once water is applied to the fire, it is no longer ventilation-limited, and it allows for more rapid and safer ventilation. However, achieving proper coordination may pose challenges due to staffing levels.
Vertical ventilation control does not mean you report to the roof and wait. You can still cut your ventilation hole. However, hold off on the task of “pushing through” the ceiling until water is in place, flowing or directed to by the engine company. Tactically, the same discipline is necessary for the outside vent (OV) firefighter, the firefighter who is tasked with horizontal ventilation by “taking the windows.” The OV must still negotiate and access his position and be prepared to take the windows. However, the windows should be kept intact until either directed by the inside team or until water is flowing into the area.
Door Control: A Critical Task
Door control is a fundamental aspect of modern firefighting, but it comes with its own set of challenges. Firefighters often carry wedges for door control, a time-honored practice that emphasizes the importance of maintaining door integrity. Designating a firefighter to control the door at the primary entry/exit point is a common approach. This firefighter evaluates conditions and ensures that the door remains open to control the flow of water. Effective communication with the hose team is essential for successful coordination.
Additionally, interior firefighters should prioritize closing doors as they advance toward the fire. This limits flow paths and fire spread, reducing the risk of getting trapped. If staffing does not permit a dedicated door control position, the hoseline can often keep the door from closing completely. It is critical for firefighters to recognize the door as a vent opening.
This tactical mindset enhances firefighter and victim safety; however, it goes against many of our tactical mindsets. When door control is deployed, our ability to see clearly as we navigate the dwelling diminishes. This, in turn, presents challenges that prevent some firefighters from seeing the true necessity.
Many firefighters are concerned that a decrease in their ability to see will slow their search or attack team advancement. This highlights the necessity for quality search training in environments where your vision is impaired. This also highlights the necessity for training moving hoselines in similar environments—not just parking lots!
Key Findings of UL Ventilation Research
- Fire Intensification with Ventilation
- A fundamental revelation is that providing a ventilation opening allows the fire to grow more rapidly. Ventilation offers the fire more oxygen, accelerating its heat release rate (HRR). It’s essential to recognize that modern interior furnishings are major contributors to this increased HRR, making it impossible to reduce temperatures significantly through ventilation alone.
- Coordination of Ventilation and Fire Attack
- A critical shift in tactics is the necessity for coordinated ventilation and fire attack. The era of spontaneously breaking windows or creating openings during a walk-around is over. Effective water application is key to fire control, allowing safer and more controlled ventilation.
- Fire Attack Crew Entrance as Ventilation
- A simple but crucial principle is that if firefighters force the door, they must also control it. This requires an understanding that there’s an average of 100 seconds to apply water before flashover becomes a real danger once an opening is made. This average depends on many variables, including room size, interior finishings, amount of fuel, and distance from ventilation opening.
- External Water Application for Self-Vented Fires
- When the fire has already self-vented through a window, the best approach may be to apply water from the exterior to “soften” the target before entering the structure. This minimizes the risk of the fire spreading to the attic if vinyl soffits are present or autoexposing to upper floors. It’s worth noting that putting water into a fire environment with a straight stream pattern doesn’t push the fire but instead reduces interior temperatures, enhancing victim survivability.
- However, it is also important to remember that if the fire is venting from the rear of the structure, it may be faster to stretch via the inside to knock down the fire. This highlights the necessity to train for both interior attack and external water application. You must have a clear understanding of the time it takes you and your crew to get water onto fire in many different scenarios.
- Vent-Enter-Isolate-Search (VEIS) Protocol
- During initial VEIS operations, refraining from breaking glass with the ladder is critical. Breaking the window should be the last step before entering the structure. Quick isolation by closing the interior door is essential for safety once firefighters have entered the room via the ladder. Proper communication, coordination, and assessment of interior conditions enable search crews to make tactical decisions and navigate through the structure efficiently.
Alternative Door Control Devices
In the quest for effective door control, various devices and methods have emerged. Dr. Michael Reick’s invention, the door curtain, has gained traction in Germany and is an option for departments with limited staffing. During testing, this curtain technology demonstrated its ability to control the flow path, limit air flow, and slow fire growth. All of these provide valuable time for firefighting operations.
Many departments do not have the necessary staffing to position a firefighter in the door control position. Each department operates differently and has different challenges. However, each department needs to prioritize achieving door control using the resources they have available.
Looking Ahead
Modern firefighting tactics require a comprehensive understanding of ventilation, coordination, and control. Ventilation is no longer a standalone tactic but must be carefully timed with water application. The 100-second window from ventilation to flashover emphasizes the critical need for precise coordination. Door control, whether achieved through wedges, designated firefighters, or innovative devices like the door curtain, plays a pivotal role in firefighter safety and the success of interior firefighting operations.
While traditional ventilation practices still have their place, the evolving science of firefighting necessitates a thoughtful and coordinated approach to keep firefighters and civilians safe on the fireground. Recognizing the positive and negative effects of every action is key to controlling fire behavior and ensuring a swift and efficient response to fire incidents.
REFERENCE
Gray, Sean, and P.J. Norwood. The Evolving Fireground: Research-Based Tactics. Fire Engineering Books, 2018. bit.ly/49YBgzd.
P.J. NORWOOD is the director of training for the Connecticut Fire Academy. He is a retired deputy chief from the East Haven (CT) Fire Department. He is on the Fire Engineering/FDIC Advisory Board and serves as UL-FSRI Technical Panel member, Fire Dynamics instructor, and Training Advisory Committee member.
SEAN GRAY is a captain with Cobb County (GA) Fire and Emergency Services and has been in the fire service since 1993. He has been a member of multiple technical panels involving fire safety research and is an appointed member of the UL FSRI Advisory Board. He coauthored the book The Evolving Fireground (Fire Engineering) and speaks nationally on research-based tactics.
