Ventilation is how members of the fire service can make a fire building do what we need it to during a fire situation. Firefighters and officers on the scene cannot control the time the fire has been burning, the fuel load or the type of construction material used to build the building.
What we can control is how we coordinate and control the ventilation of the building. Fires are hotter today then they were 20 and 30 years ago due to increased use of plastics and synthetic materials. Fires are hotter because plastic furnishings and contents burn two to three times hotter than natural materials and the newer buildings are constructed tighter, holding in the products of combustion. Plastic produces 500 times more smoke than natural material and what is smoke? It is unburned fuel waiting to ignite when the right mixture of oxygen, heat and fuel is reached. This does not always make for a safe or easy entry into the fire building. The question now has become, how have our tactics and procedures changed with the changes in the fire environment?
The basic premise of ventilation at a fire is to remove the products of combustion from the structure. This tactic has one main benefit, which is to protect the firefighters and officers inside the building trying to extinguish the fire because we let the fire, heat and smoke out of the building. If we do not have a place to push the heat and smoke out of the building and we introduce water to extinguish the fire then all of the heat and smoke will be coming back on the interior team. That will not only be dangerous, it will possibly also allow the fire to spread to uninvolved areas of the structure. If we do not create a path for the smoke and heat it will create it owns path and we might not like the results.
Ventilation must be coordinated and controlled. Does your department have procedures to control your venting? A review of your department's Standard Operational Guideline for ventilation may be necessary. The way we make the fire building behave and do what we want it to is if we use proper ventilation techniques that are coordinated and controlled. The ventilation must be controlled by someone. Some departments use the incident commander to coordinate and control the venting and others use the first officer inside the structure. Either way the ventilation is controlled by some who has been in communication with the officer in charge of the inside team, so the ventilation decisions are made with the knowledge of conditions inside.
Members must have knowledge of fire and smoke behavior and understand what the smoke is telling them. Smoke that rises rapidly is under high heat and is ready to ignite. The deeper and richer the color of the smoke is the more fuel it contains and the fire is in close proximity to this smoke. As the smoke travels away from the point or room of origin the smoke will cool and the cooling will allow the fuel contained in the smoke to be deposited on walls and ceilings. The deep color will start to reduce. If we work with the firefighters and officers in our department to understand the smoke, we will be able to recognize what the fire is telling us.
Ventilation can also be overcome by factors outside of our control. Some fires will self vent and sometimes the windows will fail. These problems might be recognized early by doing an aggressive and proactive size-up, but we might not always recognize them. Wind is a factor that can overcome all the ventilation that we attempt. Wind can intensify the fire to epic proportions and has been a contributing factor in past line-of-duty deaths. The firefighter assigned to the venting position on the exterior of the building should understand the importance of the wind and communicating the presence of wind to the interior fire forces. Even if the exterior firefighter does not vent a window, they should pass on the information about the severity of the wind outside the fire building to the interior team. Then, should a window fail that information will help insure that the interior team will have a path of retreat or an area of refuge. The importance of the information cannot be overestimated.