
By Matthew Trudeau
The tragic fire at Grenfell Tower in 2017 brought up a lot of important conversations about building evacuation, especially around shelter in place vs. evacuate. The fire, which claimed 72 lives, brought into question many fire and life safety considerations, including keeping people in place and the severe consequences if the building can no longer protect occupants in a fire. While this specific building configuration and the systems inside are different from high-rises in Canada and the United States, these lessons carry over to all building types. Whether to shelter in place or evacuate is a vital consideration for officers in command of a fire scene.
- Grenfell Report: Fire Service Needs to Be Proactive in Assessing Risks
- Lessons Learned from the Grenfell Tower Fire
- The Grenfell Tower Fire and Fire Safety Materials Testing
The difficult decision of whether an incident commander (IC) decides to keep occupants inside a structure or evacuate can fundamentally change the outcome for many people and the entire incident action plan (IAP) and have significant consequences. Leaving occupants to shelter in place relies on the IAP working, enough staff to make it happen, building services operating, and sometimes luck. Evacuating a large building with hundreds or thousands of people is a large endeavor, taking a lot of resources away from fire suppression and other fireground tasks.
Unlike the United Kingdom, the building code and building’s life safety system operate differently in the United States and Canada—they are much more robust and contain more redundancies overall. Many codes in Canada, for example, have specific provisions around exterior cladding and its fire resistance to prevent exterior flame spread and limit combustibles as well as stricter exit requirements for residential and high buildings.
A fundamental understanding of the intent of fire and life safety systems can provide clarity for ICs on what the building is trying to achieve:
- Notifying all occupants of a problem: notification by fire alarm system, water motor gong flow, and smoke alarms.
- Getting occupants away from the problem: exiting, means of egress, and minimum number of exits and fire escapes.
- Giving occupants time to get away from the problem: fire resistance ratings, maximum occupant loads, available time to evacuate vs. required time to evacuate, fire separations, sprinkler systems, compartmentalization, and smoke control systems.
To further increase the safety of these systems, redundancy is built into each of them. Multiple systems are in place to help people be aware of a fire condition, such as fire alarm and voice notification systems. The multiple interconnected systems that make up a fire alarm also have redundancies in how they are wired, protected, and backed up in case of a power loss; monitoring heat, smoke, water flow, ignition, and spark; and monitoring all its circuits for grounds, opens, and short circuits.
Many tragic events have occurred where only a single exit was available for egress during a fire. In Canada, for each increasing number of people inside a building, a minimum number of exits is required by the building code to ensure adequate exiting: One exit is required for up to 60 people inside assembly occupancies, two exits for 61-300 people, three exits for 301-1,000 people, and so on. Each exit has specific requirements for hardware, travel distance, width, and slope.
Giving occupants time to get out is an important consideration for those who can, which is an important distinction. There is a specific occupant group made for those people who can’t evacuate for numerous reasons. Door closures, fire resistance ratings, fire separations, sprinklers, travel distance, occupancy limits, and flame spread ratings are all to limit smoke and flame spread so that people have time to evacuate or be rescued by firefighters.
The question for an IC is when to keep people where they are and when to force an evacuation. The most direct answer is when the fire grows past designed levels. What does that mean? What does that look like? How do you know what the building is capable of protecting? What size fire is too big?
An evacuation can mean many things depending on the building type and classification. The general definition is moving people from a direct hazard cause by heat, smoke, and fire to outside the building to a municipal roadway. There are many cases where this isn’t possible. Codes take this into consideration to evacuate persons to the next best available option.
Engineers will design spaces and floor areas for the fire risk and hazard of the intended use. For a large open office space, a fuel load, a designed sprinkler area, an exiting plan, and other factors will be determined to be expected in that area, with a built-in safety margin. A fire size will be predicted to occur within this area in megawatts, with a safety margin, to try and protect occupants of this fire size and contain it to the area of origin.
To further complicate things, this changes for each occupancy, building, and age of the building. Fire resistance ratings, sprinkler systems, and fire separations have prescribed fires that the assemblies are required to withstand under certain conditions for a certain time based on code requirements of that building code year. Over time, those have changed to accommodate increased risk, major fires and deaths, or changes in how we use spaces.
The intent of this engineering strategy is to predict fire behavior patterns under “normal” conditions that would occur most often, plus the addition of a safety margin. Numerous factors can severely impact this original design criteria, including the following:
- Changes to the occupancy without a permit (changing an office to twice the occupants and desks).
- Changes of use (changing the office to a nightclub).
- Changes in fire dynamics (changing wood desks to synthetic material, wind-driven fires, increased stacking effect from winter/cold).
- Lack of maintenance of fire protection systems, fire separations, exits, etc.
- Other: arson, vehicle into a building.
Many code references give time durations for fire separations: between occupancies, between floor levels, and door assemblies and materials. These ratings can vary from 20 minutes to four hours, depending on the assembly and requirement. While these numbers can be helpful, ICs should use them with caution and discretion, as there are many limitations. While these provide a minimum time threshold, it is only for very specific conditions, duration, and test methodology in laboratory conditions.
The duration given should not be a time stamp but rather an overall gauge of potential. A 30-minute door may fail earlier if it hasn’t been maintained, the heat and fire are outside of its test standard, or it’s simply not matching the perfect test standard in which it was tested against. It may last 10 minutes, it may last an hour.
A two-hour fire separation could be a solid concrete floor, a heavy timber assembly, an engineered wood assembly of varying dimensions, or standard wood construction with the addition of sprinklers on both sides. Does this mean that firefighters will be safe for two hours? Not exactly, no, because of the following:
- Fire resistance ratings are measured using various techniques including cone calorimetry and Steiner tunnel testing for flame spread.
- Sprinkler systems are designed for a specific hazard, for a certain flow and pressure, and for a specified maximum number of sprinkler heads activating at once.
- Fire separations must meet minimum duration and requirements to be a rated assembly when tested to ASTM E119 fire testing. These are all under prescribed conditions in a lab or long-standing testing methodology dating back to the early 1900s.
- These minimum test standards ensure minimum overall standards but won’t accurately tell an officer outside a fire that the floor will last one hour in a Type III building.
These historic test methods, some more than 100 years old, have shaped buildings, the materials, and how we occupy buildings for as many years.
A wide range of alternative compliance solutions have been in place for decades around the world. The mindset is being integrated into North American building design. One example is when an engineer proposes a change to a building code, changing the prescribed intent with another method. This could be replacing a two-hour fire separation with a one-hour separation and a sprinkler system to “make up” two hours. When these solutions become commonplace, they are adopted as standard requirements. These alternative compliance solutions can take vastly different forms and building changes.
Very subtle changes like the two-hour fire separation example can extend up to substantial building changes. To bypass concrete high-rise construction methods, an 18-story residential building was built in 2016 using timber construction, which never was used before in Canada at this height. Many alternative solutions were employed to satisfy the intent of the building code with different materials, tools, and compliance solutions.
ICs aren’t expected to know the design criteria of buildings, potential alternative solutions, or duration of fire separations for each structure. There are significant signs that ICs can notice while on the fire scene to give them the information they need to make decisions.
Questions the IC should ask follow:
- Is the fire being contained to a single fire compartment and not breaching a fire separation?
- Is the building sprinklered, and are the sprinklers effective?
- Is the building noncombustible?
- Is there a modern fire alarm system with voice communication and smoke control?
- Has an adequate water supply been established and put in place?
- Has the fire been burning for less than 20 minutes?
- Is the tactical plan established by the IC working and effective?
If the answers to these questions are all “yes,” then the fire is going well. The building, its systems, and the IC’s tactical plan are working and effective. Generally speaking, a building is very good at protecting occupants when the fire is in a single fire compartment on a single floor in a noncombustible and sprinklered building. This is the ideal scenario.
When approaching a building with decreasing levels of fire and life safety systems in its original design, the IC should start looking at ways these systems will fail. An old building, combustible construction, questionable maintenance, no sprinklers, a high-rise, no firefighter elevators, manual standpipes, an elderly population, and an old fire alarm system should change the response, tactical plan, and even alarm level to the building. This type of worst-case scenario needs more firefighters, and plans should be in place when this fire extends to multiple floors and numerous rescues are needed.
The IC should immediately have a backup plan in case things deteriorate for each fire or if the original plan isn’t working. If there are multiple “no” answers to the questions above, the fire may be starting to overwhelm the building and its ability to contain a fire.
While there are no hard and fast rules about when to order an evacuation, having multiple systems fail or not containing a fire should signal that the plan isn’t working and this fire may keep getting worse. A fire on the eighth story of a building might have an evacuation of the building alarm for floors 6-10 and an alert for the rest of the building, or this may signal for a full-scale building evacuation automatically, depending on the fire alarm system. This single-stage or two-stage sequence evacuation is an important consideration if people remain inside a building.
Evacuating hundreds of people creates its own challenges in getting them out. Is this a seniors building? Are the HVAC systems pressurizing the stairwells keeping the means of egress clear? Have fire operations used both stairwells for fire attack? Can people on the upper floors be evacuated safely? Is there enough staffing on scene to facilitate this? Consider the building, the fire conditions, the occupancy, the egress route, and the resources before attempting a full-scale evacuation.
A full-scale evacuation in a three-story building with 50 people in the middle of summer in an average apartment complex can take place right away because there are no mobility concerns, exit concerns, or additional challenges associated with it. Get everyone out and focus efforts on fire attack and containment.
An incredibly helpful component when faced with a full-scale evacuation is the voice communication system integrated with modern fire alarms systems, if available at a building. The ability to select and page individual floors or the whole building and know the floor layout with exit locations can provide crucial information to occupants of large buildings to give them details on where to go and how to evacuate.
Where these systems are not in place, evacuations are done based on risk and resources available. Units directly impacting the fire area should be prioritized to get people out of the structure by interior or exterior means. Units sharing a common wall with a fire unit should be prioritized based on fire growth or smoke conditions. The next immediate consideration would be the fire floor, two floors above, and two floors below. The sequencing of evacuating these five floors and sending alert tones to the rest of the building is built into many new buildings. Get the people at the highest risk away from the fire and let the remaining people stand by for more instructions.
One Unique Consideration
Care facilities offer a unique set of challenges to overcome during a fire. Many terrible tragedies occurred through the 1970s, 1980s, and 1990s, requiring all care facilities and B occupancies (National Building Code of Canada) to be noncombustible and sprinklered. The major reason is the restriction in evacuation of occupants who are simply not able to leave. They could be immobile in a hospital bed, a prisoner in a jail, or without the mental capacity to leave and institutionalized. Overall, B occupancies are the following:
- Detention: jails, prisons, and holding cells.
- Care: homes for the elderly with restricted mobility and care aids, recovery centers, laboratories, and clinics with incapacitated persons.
- Treatment: hospitals, offices with same-day surgery and recovery.
Care facilities including hospitals or anywhere people are housed where they are reliant on others for their care and well-being are designed to keep them there as long as possible with the least amount of movement.
Hospitals especially don’t want to fully evacuate. The intent is always to horizontally evacuate people to the next fire compartment as the staff needed to completely remove all occupants would be overwhelmed. A single person in a hospital bed may require numerous people to move based on the medical condition. This is the reason all care facilities are required to be of noncombustible construction and be sprinklered to limit and contain fires as much as possible due to people not being able to evacuate normally.
Each care facility will have trained staff and a fire safety plan they are required to follow during certain emergencies. Jails, while noncombustible, still have evacuation plans to first contain the fire and then evacuate inmates to another holding area inside or outside and progressively farther away from the fire in a courtyard or holding area.
While there may be unique and one-off situations, the intent around a shelter in place vs. evacuation order remains the same for the IC. Is the current IAP working in containing and limiting the progress of the fire or are the conditions continuing to deteriorate? Is the fire getting better or worse? Are there multiple “no” answers, making the conditions worse? Are resources becoming overwhelmed on scene? When things are going bad, it’s time to resort to basics:
- Notify occupants to get out and where to go.
- Give them a way out: ladder, aerial, stairwell, means of egress.
- Give them time to get out: protect means of egress and exits with water, close stairwell doors to prevent smoke migration, pressurize means of egress, and provide additional rescue teams to people who need assistance.
The considerations discussed here mostly focus on the building, code requirements, and how those two become affected in a fire. This doesn’t take into consideration human factors, the people inside the building and fire crews fighting the fire. Two different departments, both going to an identical fire, may have two different outcomes based on staffing, experience, resources, and tactics.
A small department with mutual aid coming from a significant distance and with only a few trucks on scene might have the best option to contain the fire as they evacuate as many people as possible. A large, fully staffed urban department might have the significant resources to make an aggressive fire attack, keep people where they are, and contain the fire. Same fire, different strategy.
There are no hard and fast rules to complex situations where lives are on the line. Unfortunately, the right decision will be known only after the event is over. The IC will resort to his level of training and experience under extreme stress and make difficult decisions that benefit the greatest number of occupants inside.
Matthew Trudeau has been in the fire service for 23 years, the past 10 years with Vancouver (BC) Fire Rescue Services as a firefighter, fire prevention inspector, and captain of public information. He has a diploma in fire protection technology from Seneca College, a degree in fire science and emergency management from the University of Cincinnati, and a master’s in mechanical engineering with a graduate diploma in fire science from the University of Waterloo.