Designing for Human Behavior: Fire Safety Considerations
Designing for fire safety is an integral part of the job for architects who work on commercial buildings. For one thing, addressing fire safety is mandated by building codes. And with corporate responsibility becoming increasingly important to public perception, smart businesses are taking fire safety seriously.
Many architects follow long-standing best practices when designing commercial buildings. However, studies conducted in the wake of the 9/11 attacks revealed something disturbing: Best practices are based on computer modeling. And computer models are based on the assumption that people will behave in a logical, predictable manner in an emergency.
Unfortunately, that’s not always true.
The truth about human behavior in a fire emergency
People aren’t as predictable as computer models assume them to be. Studies have identified a number of behavioral factors that can cause people to delay evacuation and to evacuate more slowly once they do take action.
Resistance to task interruption: People often delay evacuation to finish tasks, make or complete phone calls, etc.
Search for social confirmation: Especially in situations where the nature or severity of the risk is unclear, people tend to discuss the situation and to then make group decisions.
Lack of confirming information: People are less likely to respond to an alarm when they’re unable to detect smoke, flames, or other sensory cues.
Personal physical barriers: Things like poor physical condition, uncomfortable footwear, and even bad weather can cause people to delay evacuation in the hope that it will turn out to be a false alarm.
Environmental barriers: Environmental barriers that can delay evacuation include lack of training, lack of knowledge of the building, a history of false alarms, or a company culture where people fear they’ll be penalized for evacuating unnecessarily.
Factors that slow the speed of evacuation
Since evacuation plans are based on specific calculations of distance, speed, traffic, etc., changing any one of those factors can cause evacuation to take longer than expected.
And there are also a few human factors that modeling doesn’t account for. People don’t always use the exit routes that were modeled. For example, instead of evacuating by the nearest emergency route, people tend to default to the route they use when entering and leaving the building on a daily basis. Not only does this lengthen evacuation time, it also disrupts traffic projections, with some exit routes becoming congested while others go unused.
Models don’t account for other common situations in an evacuation. Whether it’s a locked door or deteriorating conditions on a staircase, occupants often react unpredictably when they encounter obstacles. Some may persist at trying to get past the obstacle, causing a “traffic jam.” Others may turn around and try to move against the flow of traffic, causing confusion and slowdowns.
To add another layer of complexity, something as simple as choice of footwear can cause people (as well as everyone behind them) to move more slowly than models predicted. In addition, people can become injured or tired during evacuation, slowing their progress.
Takeaways to Consider
Human behavior in a fire emergency is a matter of ongoing research. And, since changing one factor can influence other factors downstream, it’s hard to give definitive solutions.
But the research does point to possible approaches architects can consider:
Don’t rely entirely on traffic projections when selecting exit door and stairway capacity.
Remember that simple designs are easier to navigate in an emergency, especially if building occupants have to come up with a secondary escape route because their primary route is inaccessible.
Take a double-pronged approach: First, reduce evacuation time by providing clear cues and guidance via multiple channels. Second, provide occupants with more time to evacuate by making the most of traditional fire safety options like sprinklers, fire and smoke curtains, fire-rated barriers, emergency lighting, power backups, etc.
Choose alarm systems that reduce delay by eliminating uncertainty. The best alarms systems include voice cues that provide specific information, such as the type of emergency, where it’s located and whether the alarm is a drill or real.
Consider dynamic alarm and guidance systems that adapt to changing conditions. Intelligent Evacuation Guidance Systems, for example, use cutting-edge technology to inform people of the best evacuation route based on current conditions. If that’s not in the budget, alarm systems that allow human intervention are another option for providing dynamic guidance.
Provide “areas of rescue assistance” where occupants who may not be able to evacuate safely and quickly on their own can wait for help. (This also helps prevent backups or accidents caused by people who are moving more slowly than the crowd.)
Provide highly visible signage at all points where occupants have a choice in direction.
While these are all important considerations, a valuable step you can take is to involve a Fire Protection Engineer from the very beginning of your project. These specialists are trained in all aspects of fire safety, including the impacts of human behavior as well as the latest research. They’re your best asset when it comes to designing a building that will provide its occupants with the best possible protection during a fire.
Want more tips and strategies for designing with safety in mind? Check out these tips for assessing and improving occupant safety in your building.