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simplification of mechanical systems, which, in turn, facilitated the delivery of the side core and floor plates, and the servicing requirements necessary in a premium-grade building. ‘The large floor plates placed considerable pressure on the core planning, particularly the coordination of services from [this] single-sided core,’ says Simmons. ‘We achieved this and delivered [the] UFAD HVAC system – an important consideration to ensure that the indoor environment quality (IEQ) for occupants matches the building’s premium-grade status. ‘Correctly designed and installed UFAD buildings consistently score highly on occupant satisfaction surveys when compared to other HVAC systems,’ says Simmons. ‘In Melbourne’s climate, this system provides considerable energy savings compared to other conditioning approaches. A lot of coordination work was required between the building services and structural engineers to ensure that the single-sided core worked for the floor-plate size and floor-to-floor height constraints.’ ‘The UFAD system reduces air volumes by over 30 per cent on conventional systems and provides better IEQ and floor flexibility, with services reticulation through the subfloor zone,’ says Wijewardane. ‘Sequencing of the UFAD system installation and the provision of hold points and test points during its construction were key to ensuring that installation costs were minimised. ‘In this system, air is distributed throughout the building from air-handling units (AHUs) – these are located within level one and rooftop plant rooms. In total, there are 14 AHUs providing outside air to the net lettable area (NLA) of this building. Seven AHUs provide outside air to the low-rise (Business Centre level 2 to level 10) and a further seven AHUs provide outside air to the high-rise (north-east zone levels 9 and 10, and level 11 to level 18). These units are zoned to provide air to each of the key perimeter orientations, and two internal zones per floor. Therefore, each AHU serves multiple floors.
‘The mechanical ventilation system has been designed to deliver a 100 per cent improvement on the minimum outside air requirement as per AS 1668.2-1991. Occupancy of the tower is defined as one person per 10 square metres for office NLA – this corresponds to the provision of outside air at 1.5 litres per second per square metre, which exceeds best practice. As per AS 1668.2-1991, the minimum outside air requirement for this development is 7.5 litres per second per person, and 171 Collins Street exceeds this requirement.’ Simplicity was a major focus of 171 Collins Street’s construction. The practical approach to sustainability is evidence that a wellconsidered, efficiently planned building and systems design can deliver a cost-effective, world-leading sustainable building that sets a high standard in energy and water efficiency. ‘In order to reduce potable water consumption by building occupants, [we] incorporated water-efficient fixtures and fittings, rainwater collection and re-use, as well as greywater recycling,’ says Wijewardane. ‘The 171 Collins Street development has a total roof area of 2975 square metres, which has been designed to collect
and drain rainwater into a 155,000-litre rainwater storage tank. Prior to use, the harvested rainwater undergoes adequate treatment, consisting of an initial firstflush diversion system, followed by micron filtration and ultraviolet disinfection. Following treatment, the rainwater is then reticulated to the 20,000-litre header (break) tank located on the roof, where it is stored with treated greywater prior to being used in the cooling towers. ‘Greywater is recovered from all the showers (no sinks) within the office building, and directed to the greywater treatment plant,’ says Wijewardane. ‘Following extensive treatment to Class-A water-quality requirements, the greywater is fed for toilet flushing and cooling tower requirements. In the event of the mixed water source becoming exhausted, automatic mains backup from the 60,000-litre potable cold water tank situated on the roof activates, and continues to supply the non-potable water demands. ‘The building includes the provision of six cooling towers for heat rejection purposes. The water supply to the cooling tower and toilet flushing has been supplied from three different sources: treated rainwater,
Facility PerspectiveS | VOLUME 8 NUMBER 4
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