Jane Embury looks at fire compartmentation in new tall buildings
The 20th anniversary of 9/11 is fast approaching.
In the wake of the Twin Towers, their replacement, the One World Trade Center opened in 2014.
Although 9/11 was a manmade disaster, the Grenfell Tower fire again underlines that tragedies in tall buildings do happen.
In the wake of Grenfell, the government has moved to tighten up fire and building safety.
In particular, we’ve welcomed the appointment of a specific person who will be responsible for safety from the design stage onwards.
His or her responsibility will extend throughout the building stages, up to ten years after completion.
But we’ve also warned that evacuation estimates for tall buildings can be overly optimistic. A lesson from 9/11 is that people don’t immediately evacuate when an alarm sounds.
But another tragedy from Grenfell Tower is that it’s once again been a case of “codifying by catastrophe.” Too often, it takes tragedy to learn lessons after the event, rather than anticipate fire safety issues.
As the construction industry recovers from the pandemic, it’s worth remembering that London is planning a huge expansion of tall buildings.
According to New London Architecture’s annual review of skyscrapers over 20 storeys or more, there are 587 tall buildings in the pipeline in London.
Of those, 310 have been granted full planning permission. A total of 35 tower blocks were completed last year.
A 42-storey tower at Paddington’s Merchant Square was finished last year. It has 436 flats and is now west London’s tallest apartment building.
Nine Elms saw the completion of an even taller skyscraper – the 53-storey One Thames City.
East London, has the largest number of tall buildings in planning – mainly in Tower Hamlets, Newham and Greenwich. Most will be residential.
The tallest building in the USA, the home of the skyscraper, is the One World Trade Centre, at 541 metres. It stands as a memorial and a reminder of all the lives that were lost on 9/11.
But that will eventually be dwarfed by the Jeddah Tower in Saudi Arabia – the first habitable building to pass the one kilometre mark. Work has paused because of Covid-19 and no completion date has been set.
Construction will reputedly require 500,000 cubic metres of concrete and 80,000 tons of steel.
It will be 173 metres taller than Dubai’s Burj Khalifa, currently the world’s tallest building.
Building the Jeddah Tower, as with any tall building in a hot climate, involves great challenge. Not least how to pump wet cement half a mile upwards.
Design of the new ultra-tall buildings was first influenced by a report from the US National Institute of Standards and Technology (NIST) into the collapse of the Twin Towers. The towers were just over 400 metres tall.
The report found that “the towers withstood the impacts and would have remained standing were it not for the dislodged insulation (fireproofing) and the subsequent multi-floor fires.”
Subsequent reports have highlighted the need for continued research into sustainable materials, technologies and design strategies in tall buildings on fire and life safety performance.
That research continues – for example into appropriate cladding in the wake of the Grenfell Tower fire.
We have also publicly raised concerns about how fire regulations were being applied across parts of the Middle East. We have also changed our certification processes. Now, we only issue site-specific fire certifications.
Our primary business at Wrightstyle is the supply of integrated glass and steel framing systems. Each system is tested as one unit. In a fire situation, if one of those components fails, they both fail – with potentially catastrophic consequences.
As we build the new generation of super-buildings, fire safety takes on a whole new dimension. Beyond sprinkler systems – how do you tackle a fire a kilometre up in the sky?
The most effective way of dealing with fire in tall buildings is by fire compartmentation. In other words, keeping the fire contained in one protected area and preventing it from spreading.
It’s an issue we’ve written about many times before, most recently here.
A rule of thumb for fire safety in supertall buildings is that any fire should be able to burn itself out, without external intervention, and without building collapse.
That allows for a safe and orderly evacuation, although some can be “defended in place.” These might include the elderly or infirm.
Over the years, we’ve seen the good, bad and the ugly of fire safety design.
We hope that the new cities in the sky have fire containment strategies to ensure everyone’s safety.