The new incoming British Standard 9999 is a leap forward in fire safety – but it still contains hidden dangers for both firefighters and the public – according to Manchester-based smoke control specialists Fire Engineering Associates.

For, although Section 28 recommends properly designed and installed pressure differential systems for firefighting shafts in buildings more than 30 metres high, and basements more than 10 metres deep, it allows natural ventilation as an alternative method in smaller commercial and residential buildings.

“And that’s where the danger comes in,” says chartered engineer and FEA associate Jim Wild – a fan engineering consultant who specialises in fire smoke control systems.

“Natural ventilation systems have been around since 1971 and they have been criticised from the beginning. The idea is to allow smoke to get into the escape or entry route and then be ventilated … which is not a good start.

“This method is also very susceptible to external wind conditions and early research showed that, even with the very best alignment of vent outlet with prevailing wind, smoke remained in the escape routes on almost 50% of occasions.

“The recommendation that natural vent outlets only be located where they are always subject to negative wind pressures is very difficult, if not impossible, to achieve in built up areas – and historically such recommendations have often been ignored.

“For all these reasons firefighters could, even now, still find themselves having to enter smoke-filled buildings – which is very dangerous. It would have been safer if the new standard had excluded this natural ventilation option altogether.”

Occupants of a building could be endangered, too – because BS 9999 does not clearly recognise that EN12101 Part 6 also applies to escape shafts. So it does little, as yet, for escaping occupants. Hopefully, this will be dealt with in future revisions.”

Overall, BS 9999 – which comes into force in April – is “wonderful news for the industry and we welcome it almost unreservedly,” says Fire Engineering Associates Technical Director, Dave Ogden whose experience in pressurisation systems puts him in a narrow band of smoke control engineers whose contemporaries, more typically, have natural ventilation backgrounds.

“A pressure differential system is the only method where the object of the design is to keep smoke out of the escape routes,” he says. “Unfortunately, design failure in early systems gave pressurisation a bad name but Fire Engineering Associates has always supported it because, correctly designed and installed, it is easily the best form of protection.”

Dave has been behind more than 100 pressurisation systems from Fire Engineering Associates over the last decade – often involving several integrated stairwells. These have included Ontario Tower, in London’s Dockland, which has two pressurised systems – a fire fighting shaft covering 30 floors and a escape stair of 21 stories.


Issued on behalf of Fire Engineering Associates Limited, Unit Nine, The School House, Second Avenue, Trafford Park, Manchester M17 1DZ; Tel: 0161 8727760
Press enquiries: Graham King – tel: 0161 976 2729, 07850 280213, e-mail:

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