- By Witt
- In Case Study, PSB
123 Victoria Street – London
PSB UK Ltd has been requested to provide a smoke ventilation strategy for the smoke control at the Land Securities project at 123 Victoria Street, London.
There is a requirement to protect the “Fire-Fighting” stairwell lobbies via a natural smoke ventilation shaft: this will be achieved by a BRE79204 compliant solution. In addition, due to the location of the development, the smoke control requirements of LDSA section 20 apply.
The objective of this report is to support the Building Regulations application for the scheme.
Typically the report provides commentary on smoke extract design strategy issues.
The proposals presented in this report are primarily based around BRE79204 rep[ort, an alternative smoke control system for BS5588-5 fire-fighting shafts
Compliance with BRE79204
The system proposed is fully compliant with the requirements of BRE79204, comprising of a system as follows when read in conjunction with the following notes.
The smoke shaft should be closed at the bottom and have a single opening at the top too allow ventilation of the smoke.
As the bre79204 design of a smoke shaft has been modelled using CFD for buildings up to at least 101 storeys in height, no further CFD modelling is required.
The ventilator used to vent smoke from the lobby to the smoke shaft should be an automatically opening Vent (AOV) (With manual override), activated on detection of smoke within the fire fighting lobby, via the buildings fire alarm system.
The lobby ventilator has a geometric free area of at least 1.5m² that comprises of a smoke damper and grill over with the minimum dimension of both the width and height of the ventilator being 1m.
The stairwell ceiling ventilator with a geometric free area of at least is a 1m² AOV is (with override controls to open and close the vent.
The system is activated on detection of smoke within the fire-fighting lobby derived from the buildings fire alarm system.
Component Details
Control Panel
The control system will require a fire signal per floor (upon fire open VFC) from the buildings addressable fire alarm system. Theses will be derived from smoke being detected at all levels being protected by the smoke control system (and possibly the stair if deemed required.
The control panel will be supplied by a generator backed essential 230v 10A single phase supply and has batteries to provide secondary power in the event of mains failure.
Note to reduce the risk of incorrect operation etc there are no local switches adjacent to the corridor/lobby vents) to provide manual operation. A Single fireman’s override switch at the panel is to be installed in an unobscured position. On activation of the switch override facility will be provided via a touch screen HMI giving manual operation of “opening all vents” or “closing all vents”.
