Grenfell: Experts’ ‘unsparing criticism’ of smoke ventilation system refurb

But counsel for the engineering firm PSB that designed the system argued that it did meet Building Regulations and that it did not accept the assessment of the Inquiry’s experts, Dr Barbara Lane and fire consultant Beryl Menzies.

In his opening statement, Adrian Williamson QC, addressing the panel on behalf of the bereaved, survivors and residents he represents, criticised what he termed as failures during the refurbishment at the design, commissioning, training and maintenance stages of the smoke control system in the building.

Lack of information

He told the Inquiry how in September 2013, in the early stages of the refurbishment of the tower, engineer Max Fordham sought test certificates for the existing system from the Kensington and Chelsea Tenant Management Organisation (TMO) and “immediately ran into difficulties”. The TMO said it was having problems obtaining information on the system from maintenance contractor RGE and it did not appear that the TMO itself held the material.

Meanwhile, Williamson said, PSB was contacted as late as November 2013, after the concept stage, and “even then only when it was belatedly identified that an engineering solution would be required”.

In 2014, Max Fordham’s Matt Cross Smith chased RGE for Grenfell’s SVS maintenance records. But, he said, RGE explained that as they did not believe the system worked, they could not test it.

A report eventually obtained by Cross Smith contained errors and did not answer his questions. Williamson said: “RGE had paid little attention to the upkeep of this system which was critical for safety, and which was in a state of neglect following the combined inattention of the TMO and their maintenance contractors. It is apparent that the situation remained unsatisfactory throughout 2014, and that the team working on the refurbishment were struggling to get on top of the automatic opening ventilation (AOV) issues.”

Design criticisms

Williamson was also critical of the system designed by PSB as part of the refurbishment. He said: “There are a number of different, recognised mechanical smoke control system design options that could have been adopted by PSB and which would have been compliant with both the Smoke Control Association (SCA) guidelines and Approved Document B (ADB). These options were not considered by PSB, however. There does not appear to have been any formal consideration of the suitability or advantages or disadvantages of any of the recognised design bases which Dr Lane sets out in her reports. The Inquiry’s experts have indeed been unsparing in their criticisms of the work done on the SVS.

“PSB’s design proposal was performance−based and only adopted the appropriate air flow criteria across the stair door from the [British] standard. It did not adopt the recommended pressure differential criteria in the various spaces as mandated by the standard, nor the recommended fan temperature which was appropriate for extracting smoke and hot gases from the fire zone, as Ms Menzies points out. The dampers serving the lobby smoke control at every level were required to be smoke control dampers by reference to the SCA guide and the British Standard. In Grenfell Tower, the minimum required fire resistance duration was E60S to comply with the ADB. PSB did not specify smoke control dampers, and instead specified a product rather than a fire performance. This was the Gilberts Series 54 damper.”

Williamson said that an analysis by Dr Lane found that these dampers have “never been fully tested” to the relevant standard for fire dampers, nor formally classified as such.

He continued: “A fire damper is in any event the lowest possible damper standard required in the ADB, and is expressly cited as inappropriate for use on protected escape routes. Dr Lane concludes that the dampers installed across the system were non−compliant with British Standards.”

Alleged building control failings

Meanwhile, Williamson also highlighted Menzies’ criticism of building control’s approach to the commissioning of the system. He highlighted Menzies' assertion that building control did not accept the commissioning certificate for the renovated SVS and that there was no indication that further commissioning of the amended smoke control system was undertaken. He said: “Building control took a characteristically hands−off attitude. As Ms Menzies puts it, there was on their part a failure not to require further commissioning and not to have witnessed a further demonstration. Ultimately, Ms Menzies’ view is that a completion certificate for the refurbishment works should not have been issued by building control.”

The Inquiry also heard Williamson claim that maintenance of the new system was “equally inadequate”. Just a week before the fire, on 6 June 2017, subcontractor JS Wright notified PSB that it had received a defect notice from refurbishment main contractor Rydon that the AOVs were not opening up and requested an appointment be arranged to attend to resolve the matter.”

Work to repair the fault was booked but not carried out before the fire.

Williamson concluded: “It is likely that all the failures that I have highlighted, and which are set out in detail in the expert evidence, contributed to the system not functioning on the night of 14 June 2017.”

In her opening statement, Stephanie Barwise QC, representing the bereaved, survivors and residents, said that PSB had demanded an opportunity to challenge Dr Lane’s evidence but “has not availed itself of the opportunity…which it has thus far been afforded”.

She continued: “Importantly, Dr Lane alerted PSB to two specific points: first , the system as designed was not a pressure differential system as defined by ADB2 and BS EN 12101−6, and was therefore a bespoke system; second, that as the performance criteria of the system were not defined, she was unable to confirm that the system complied with the functional requirements of the Building Regulations. That was throwing down a gauntlet to PSB to justify its system. PSB, however, failed to pick up the gauntlet, in that even now, after two witness statements from its principal designer, Mr Mahoney, the explanation for his chosen design, including the assumed design conditions and performance standard he hoped to achieve, are nowhere set out. PSB has therefore had since April 2018 to explain the basis of its design and yet has failed to do so.”

PSB's response

But Lee Bennett, representing PSB said the company had only had little time to examine the expert smoke control reports. He also described the system designed for Grenfell Tower by PSB as a “reasonable design response”.

Bennett said: “Expert reports on smoke control have been disclosed to core participants only very recently. Disclosure was completed on 9 June 2021. The reports of Ms Menzies and Dr Lane comprise 765 pages of detailed expert evidence. I’m not looking for sympathy, but this chronology does place PSB and its witnesses, from whom the Inquiry wishes to hear, in a difficult position, with exceptionally short time to consider that material. Evidently, from the written and oral submissions that the Inquiry has received, some core participants are wedded entirely to the assessment provided by Dr Lane, and their submissions are, in effect, an articulation of the contents of Dr Lane’s report. Now, PSB continues to review the detail of those reports but, to be clear, PSB does not accept the assessment made by Dr Lane and will look to challenge it.”

Bennett said that where Building Regulations applied to PSB’s SVS at Grenfell Tower, it did comply with the relevant requirements of schedule 1. He said: “We submit that the system provided, so far as was reasonable, in the context of an existing legacy residential building, ‘appropriate means of escape’, which is B1, and, secondly, reasonable facilities to assist firefighters , which is B5."

When it came to testing and commissioning of the system, he added: “Whilst acknowledging that the paperwork and record−keeping was less than optimum in relation to the testing and commissioning process, PSB presently considers that the testing and commissioning of the system was completed satisfactorily.”

He added: “PSB is confident that a complete and objective view of all the evidence ought to result in the conclusion that the system did operate on the night of the fire , at least during the period when the circumstances remained within the designed−for conditions.”

The Inquiry continues.