Jun 16, 2017 03:44 PM EDT
Modern high rise buildings are supposed to be able to withstand fires and, more importantly, contain them inside the unit where the fire started. So what happened in this week's fire that engulfed the Grenfell Tower in London? Several factors seem to be at play. By understanding them, we can take steps to insure that this type of tragedy never happens again.
Firefighters and experts say that the exterior cladding, an aluminum composite material builders added in the 1970s as part of a refurbishing, are to blame for the quick spread of the fire to other floors of the building. The panels were supposed to provide insulation from weather and improve the exterior appearance of the building. However, when a refrigerator on the 4th floor malfunctioned and caused an electrical short, the resulting fire it was able to crawl up the outside of the building within minutes and spread quickly trapping residents inside and engulfing the building in flames. Because it was a hot night, many windows were open, allowing the fire to re-enter the building at several points.
The only escape route in the building was lone the central fire stairwell. Some residents escaped using this route. Some residents were told by emergency services over the phone to "put towels around doors and stay put until help arrived." This would work if the building had been compartmentalised, preventing the spread of the fire from floor to floor. Grenfell Tower was not well compartmentalized, and many who received this advice and followed it are likely dead.
The death toll is expected to climb to over 100 with some bodies charred beyond recognition and unable to be identified even by DNA evidence.
Residents had complained for years about safety concerns in the building, including shoddy maintenence and smoking electrical equipment as well as inadequate areas for emergency vehicles to access the building. Concerns fell on deaf ears according to residents. It was revealed on Friday that building management had ordered a cheaper, less fire-resistant cladding than one available from the same company that would have cost only 25 cents more per square foot.
Part of the reason that the insulators are to blame for the quick spread of the fire is that they are usually foamed hydrocarbons which "burn pretty well" according to Alexander Morgan, head of the Applied Combustion and Energy Group at the University of Dayton Research Institute and editor in chief of the Journal of Fire Sciences. If a fire in a single unit spreads out a window, it can catch these panels on fire pretty easily and spread the blaze to other parts of the building. Planning documents detailing the recent refurbishment of the block did not refer to a type of fire barrier that safety experts said must be used when high-rise blocks are re-clad.
The key is to "layer in systems" says Robert Solomon, a fire protection engineer with the National Fire Protection Association. "Automated sprinklers, a robust fire alarm system that includes emergency voice evacuation system. You'll get some verbal instructions, and then once the fire department arrives they can use that system to provide real-time information."
The Grenfell Tower did not have a central fire alarm or adequate fire sprinklers installed.
Egress is the most important factor in any high rise building fire. The Grenfell Tower had only one stairwell for 600 residents, including many seniors with limited mobility. This is one area in which Britain lags the developed world -- almost every other developed country requires a minimum two stairwells for egress in buildings of this kind. A spokesman for the Tall Buildings Fire Safety Network said his "foreign colleagues are staggered" that the United Kingdom lacks this most elementary requirement for building safety.
"If you have a building that wasn't built to allow that kind of strategy, then you need to look at other means, like a good egress system," according to Carl Baldassarra, head of the fire protection practice at the engineering firm Wiss, Janney, Elstner Associates.
Egress is a complicated issue in fire safety. Crowds of people pour down a staircase with others joining at the entry for that one staircase at each floor. Add emergency crews and first responders trying to go up the same staircase. The bottleneck is inevitable.
Several options have been put forward in the past as ideas for a speedy egress. Slides, zip-lines and other ideas have been floated, but none has been proven to be effective.
This is a developing story.
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