In early 2007 Myer kicked off a staged refurbishment of the Melbourne Bourke Street outlet, requiring new building services throughout.
NDY was appointed to undertake the design, documentation and construction phase administration of the Building Services for the project for the following disciplines: Mechanical, Electrical, Communications, Fire protection, Lifts, Acoustic, Fire Engineering, Security, and Lighting.
One of the key design features of the development was an inclined atrium, open on all sides, which linked all floors from ground to level six. This presented numerous challenges to the fire protection and fire engineering team, specifically:
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detection of smoke from a fire at the base of the atrium
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fire suppression of a fire at the base of the atrium
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minimising the spread of smoke from a fire from one floor to the next.
A traditional approach to smoke detection would not work in this scenario, so a performance based design solution was engineered, consisting of various different forms of fire detection within the atrium, all working simultaneously to provide early warning of fire. Flame type detectors were installed at the base of the atrium, while a series of aspirated smoke detectors and beam type smoke detectors were installed within the atrium at various levels.
Myer also wanted to use the atrium void for display purposes, such as large hanging displays and so beam detectors were strategically placed within the atrium void, concealed within the escalators.
Triple waveband infrared flame detectors were installed due to their superior false alarm immunity. The optical sensors and filters within the flame detectors have been carefully selected to ensure the greatest degree of spectral matching to the radiant energy emissions of a fire.
The Xtralis VESDA product was selected for the aspirated smoke detection system, which utilised a high-efficiency aspirator to draw air through a distributed pipe network and then through a laser light source, able to detect smoke from a fire at the earliest stage using the light scatter principal of smoke detection.
Due to the size of the atrium and expected fuel load at the base, a traditional automatic fire sprinkler system was not deemed adequate. Consequently a deluge type automatic fire sprinkler system was designed. Upon sensing a fire at the base of the atrium, a fast acting deluge valve is programmed to automatically release water into a network of fire sprinkler pipework, with open nozzles around the atrium base and effectively deluging the fire with water. Simultaneous activation of two detection systems was employed to minimise the risk of deluge system activation from a false alarm.
Thirdly, to reduce the spread of smoke to multiple floors through the atrium, a series of both glazed and plasterboard smoke baffles have been integrated into the architectural design. In addition, a smoke exhaust system, also linked to the fire detection and alarm system has been incorporated into the top of the atrium, capable of exhausting 140,000 litres/sec.
The fire engineering team utilised computation fluid dynamics (CFD) software Fire Dynamics Simulator (FDS) to model the movement of smoke within the building, determine suitable size smoke exhaust fans and rationalise the smoke baffle design.
