Pratley & Partners

Smoke Ventilation at Grenfell – What Went Wrong?

Friday, 24 January 2020

According to a report issued by Dr Barbara Lane – appointed by the Grenfell Tower Inquiry – the smoke control system was designed to operate on one floor only, the floor where smoke was detected. The system worked based on the assumption that any smoke which was detected would be evacuated, and that the fire would be contained within the flat.

It was assumed that any potential fire would start within a single flat, and on this occasion the assumption was correct. Had the fire been contained within the flat where it started, the system would have worked to specification, being originally designed to clear smoke from a single lobby.

Why Did the Evacuation Routes Fail?

The system was not designed to clear smoke from multiple floor lobbies at the same time. This single failing has been cited as a factor in preventing rapid and safe evacuation of the building. However, the tragedy was compounded by the ease in which the cladding of the building caught fire and smoke was sucked in to the building interior.

Once the smoke and fumes had contaminated the inner lobbies and stairwells of the tower, the single escape route for most of the residents was cut off. This is the single biggest issue with high rise buildings – the only evacuation route is down through the middle of the interior of the building. The problem is that if the ventilation system fails to operate as it was designed to due to external influences (non fireproof cladding as an example).

Low Rise vs High Rise Buildings

This is not such an issue in low rise building where there are potentially a greater number of fire escape routes. Low rise building tend to have a larger base footprint than high rise buildings, so the potential for multiple escape routes to be built in to the design is available.

Smoke is the Killer

Low rise buildings however still need a smoke evacuation system to ensure escape routes, lobbies and stairwells are kept clear of smoke. The primary cause of death in victims of fire is smoke inhalation. Typically the hot smoke will injure or kill by a combination of thermal damage to lungs and airways, pulmonary irritation, poisoning and subsequent swelling of airways as a result of inhalation of carbon monoxide, cyanide and other combustion by-products.

Smoke is also the primary cause of panic when there is a fire. When people panic the flight mode kicks in and that is when injuries and death may occur as a result of crush injuries caused in ‘stampede mode’ before any of the symptoms of smoke inhalation have the chance to occur.

Keeping the building as smoke free as possible when a fire does occur is an essential element in safe evacuation of the building. Fire dampening and extinguishing systems will kick in, but not before smoke has been generated by the fire.

Fume and smoke ventilation by way of a combination of natural ventilation and forced ventilation is a proven element in preventing injuries (such as the aforementioned) and death. Keeping escape routes clear allows rapid evacuation and reduces the potential for casualties, as well as keeping access clear for the fire and other emergency services.

Permanent high level window vents in a roof or atrium structure for example can be easily opened by way of electric window controls.

Does your building have adequate roof vents for rapid smoke ventilation? Are they easily accessible by manual or electrical control systems? A simple check now and, if required, installation of suitable vents and venting controls can be a life saver in the future.

Fire prevention in buildings and modern safety practices has all but banished injury and death as a result of fire. When it does occur, in a small building such as commercial offices, schools or industrial buildings, it always makes for tragic headlines, such as those when the Grenfell Tower tragedy was reported.

BY taking steps now, making sure your vents and window openers are in place and in good working order, you are taking steps to avoid the next tragic headlines being yours.


 

 

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