Smoke Vent Failure Points To Bigger Problems

Posted in The Industry on September 08, 2018


There has been widespread criticism of the smoke ventilation system at Grenfell Tower, but its apparent failure is not quite as clear-cut as many might think.

Grenfell Tower residents and firefighters reported finding it almost impossible to navigate the stairwells during the horrific fire that engulfed the building due to the huge amount of smoke billowing around inside.

While much of the focus in the aftermath has been on the cladding and why the fire was able to travel so quickly up the outside of the structure, the fact that the smoke ventilation system appeared to fail was a huge source of concern because firefighters struggled to get people out once the delayed decision to evacuate was made.

Therefore, the public inquiry quickly commissioned an interim report by Arup fire engineer Dr Barbara Lane to look into what went wrong.

She established that the installed system was not compliant with the building regulations and that the original system designed by Max Fordham had been changed at some point. She also concluded that the system was not properly commissioned.
This actually raises more questions than answers. There should have been testing and service records in order for the system to be signed off under the terms of Regulatory Reform (Fire Safety) Order. It is also not clear why she thinks the system did not comply with the Building Regulations.

Protected

Dr Lane also stated that fire safety measures at Grenfell were designed for a single fire on a single level and therefore "could not have protected lobbies and the stair from smoke generated by fire on multiple levels". That is standard practice and, therefore, to be expected.

Most fire safety systems are designed to work floor-by-floor and this is stipulated in Approved Document B that accompanies the regulations. It, therefore, appears that it would be more accurate to say the design intent was fine and that the installed system had absolutely no chance of keeping the stairwells free of smoke because the fire was raging on multiple levels and moving at rapid speed up the outside of the building.

The fact is that the Grenfell fire was unprecedented and no smoke control system would have been able to cope with the extraordinary circumstances caused by a fire spreading so quickly up the outside of the building. Sprinklers would not have coped either.
In suggesting, however, that the original design was changed and something different installed she goes to a much deeper problem, which was also highlighted by the Hackitt Review and is more to do with the need to establish professional competence.

The implication is that 'value engineering' of original designs may have led to changes to the fire safety systems and these could have left residents exposed to increased risk.

The 'race to the bottom' in a bid to undercut prices at the expense of doing the right thing is far too commonplace and compromises too many well-intentioned building services designs.

This does not mean, however, that all these safety measures are not essential – most fires will not be as extraordinary as Grenfell and, in the vast majority of cases, the way we design and install fire and smoke control systems in the UK will work perfectly well.

Therefore, the inquiry into what went wrong at Grenfell should not automatically lead to new regulations and new methods of providing fire and smoke control in buildings. Rather it should prompt a re-examination of how our existing standards and regulations are being applied and enforced.

This means the building engineering sector has to increase its focus on professional competence and make sure that people are only working on aspects of building design for which they are qualified. They also need to know what they are looking at and do not, therefore, 'value engineer' out critical elements that might compromise the safety of the building.

Banning

The London Fire Brigade is clear on this point too and has spotted the inherent danger in the inquiry focussing too much on specific technical aspects of the Grenfell tragedy. It has just written to the Ministry of Housing, Communities and Local Government warning that it needs to go much further than simply banning combustible materials used on building exteriors.

"While we are supportive of an initial ban, this is a short term solution that won't fix what is essentially a broken system," it told the department. "The banning of flammable materials is an important step in reassuring the public, but it is only part of the problem that needs to be rectified.

"A ban must be followed up with a concerted effort to implement the other reforms suggested in Dame Judith Hackitt's independent review of building regulations and fire safety to ensure we have a robust system of testing and regulation and that only competent persons are making decisions about the materials we use in and on our buildings in the future."

In other words, if you are going to make changes to the fire safety system during construction or refurbishment you should make sure a fully competent engineer reviews those changes first. If the prime motivation for the changes is to save money, then think again.


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