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Colt has cut the cost of smoke extraction in a new London business hotel by installing its Colt
Shaft fan-powered system.
M&E contractor Derry Building Services of Newark initially approached Colt for a pressurisation
system. Simon Palmer, mechanical contracts engineer, explained: "Colt proposed using its shaft
system as an alternative. Not only is this option half the cost, it requires a shaft of only 0.6m2
compared with 3m2 for a conventional BRE shaft. This represented an 80 per cent reduction in the floor
space required. The additional floor space available for hotel rooms will significantly increase our
client's profits".
The project involved Colt supplying, installing, wiring and commissioning its Colt Shaft for
the 205-bedroom, seven-storey Hoxton Hotel in the heart of the City of London. This is the
first contract in which Colt Shaft has been specified.
In the event of a fire, the Colt Shaft - which runs vertically through the hotel - would use a fan
system to draw smoke away from the fire fighting core to ensure access for the emergency services.
The Colt Shaft system has been approved by the London Fire Brigade for use in this application,
following tests witnessed at Colt International's facility in Havant, Hampshire.
The Colt Shaft solves two problems commonly associated with mechanical extraction. First, since
the lobby is fire rated, the area of ventilation into it is usually small, so even a small amount
of extract will cause a high negative pressure in the lobby, which could make doors difficult to
open. Secondly, negative pressure could cause smoke to be drawn into the lobby from the fire
compartment, with devastating effect.
However, the Colt Shaft overcomes excessive negative pressures without compromising the integrity
of the stairs and lobby by automatically reducing the ventilation rate when the lobby doors are
closed. It does this via a pressure sensor linked into the control system that varies the fan speed.
With all doors open, the fan runs at full speed to extract smoke discharging from the accommodation.
With all doors closed, the fan runs at minimum speed to help mop up smoke leaking past the closed
door. In intermediate conditions, the fan speed modulates to ensure adequate ventilation without
excessive depressurisation.
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The £ 17 million Hoxton Hotel, which opened on September 1, is the brainchild of Sinclair Beecham,
the co-founder of the Prjt a Manger sandwich chain, who has invested more than #1m of his own money
in the project.
The consulting engineer was Geoff Handley of Building Services Design in Monmouth. The architect was
the London-based Bell Slater Partnership and the contractor was Bowmer and Kirkland of Belper,
Derbyshire.
For more information on Colt Shaft, click here.
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