In the first part of this article, Jane Embury looked at a worrying trend by some contractors to reduce fire glazing specifications from 60 to 30 minutes. Here she looks at other evacuation factors, including research from 9/11.
Earlier this week, I raised the issue of some contractors compromising on fire safety.
Their justification is that, if a building can be safely evacuated in 30 minutes, there is no need to specify fire glazing safety to 60 minutes. The cheaper option will be more than sufficient, they would argue.
Wrong. As much as two-thirds of the time it takes people to exit a building after an alarm is start-up time. That’s time spent dithering or looking for more information.
If there’s no visible smoke or fire, people will assume the alarm is some kind of test or mistake. Even if they do take it seriously, they don’t know which might be the safest route.
Nor might they evacuate until co-workers also evacuate, or if their boss tells them to evacuate. Nobody wants to appear scared in front of colleagues.
But it’s when danger does become apparent that the psychology of evacuation becomes more complicated. For example, what if someone encounters smoke during their evacuation? Will he or she choose to go through it, even if they know it’s the quickest route to an exit?
Research indicates that most people, understandably, will be disinclined to move through smoke if it seems to them to be “thick” or “black.” There is also the assumption that there’s no smoke without fire.
(In fact, smoke inhalation kills more people than fire).
There are other factors at work, such as familiarity with the escape route. Research suggests that people are often more likely to use a distant, but familiar, exit than an unfamiliar exit nearby.
This was often attributed to panic. Social scientists now agree that seemingly-irrational flight behaviour to a more distant exit is perfectly rational. They are rationally seeking an exit with which they are familiar.
Group dynamics also plays a part; how a number of people, in different states of fear, influence one another.
Evidence suggests, for example, that people evacuate buildings alongside colleagues with whom they have an emotional attachment.
In a shopping centre that social dynamic may be familial, with parents trying to control small children. How does the family group react, when each member is instinctively responding in a different way?
All of those factors, and many other variables, can influence how levels of protection should be applied within buildings.
The risk assessment should not only calculate the time it will take to evacuate along designated or undesignated routes. It should also build in additional time to allow for the elderly or infirm, or the simply complacent.
Those escape routes – even if they’re not designated escape routes – and the likely numbers of people using them, will also have an impact on the size of intermediate and exterior doors.
The psychology of fire can have terrible consequences, as a study found on the 9/11 evacuation of the World Trade Center.
Those involved gave four factors that affected their decision to begin evacuating. One, a perceived ability to walk down multiple flights of stairs. Two, experience in evacuation, including knowledge of stairwell locations and if they led to street level exits. Three, concern over leaving their work areas without the approval of managers. Four, information about what had happened and what floors were involved.
The research also suggested that many people delayed their evacuation to, for example, make a telephone call or shut down their computer.
On top of indecision about what exit route to take, progress was also slowed for some with poor mobility or, simply, inadequate footwear.
It provides a stark example to use behavioural science as well as computer modelling to design a more predictive evacuation model.
As a company that understands fire dynamics, we have steel glazing systems – doors, screens, and curtain walling – that can provide up to 120 minutes of fire resistance. Those protect against fire, radiant heat and smoke.
Our compatible systems, with the glass and steel framing systems tested together, are accredited to EU, US and Asia Pacific standards.
Our strong advice is to always specify the glass and steel as one unit. In a fire situation, the glass will only be as protective as its frame, and vice versa. Specify each component separately, and you run the risk of one failing. If one fails, the whole fire protective barrier fails.
Fire can be friend or foe. Controlled, it can warm us and cook our food. Uncontrolled, it can be extremely dangerous, and the safest strategy is to move away from it as quickly as possible.
That’s what fire alarms are meant to warn us to do, even if human psychology delays our response times. It makes our advanced glazing systems even more important.
They contain fire away from escape routes and give everyone more than enough time to escape. Containment also limits damage by fire, smoke or the water from fire hoses. It therefore allows for business continuity.
So: to all those contractors who are considering cutting a fire specification from 60 minutes to 30 minutes. Do you still think it’s a good idea?