Now and later
The 44-storey Chifley North tower is one of the more prominent commercial office buildings on the central Sydney CBD skyline. Designed by New York architects Kohn Pederson Fox and built in 1992, the tower sits on a three-storey, mixed-use podium – Chifley Plaza – that spans the entirety of the city block. In August 2019, Charter Hall Group partnered with the property’s owner, GIC, to acquire the lease-hold of Chifley Tower and set about planning the addition of a second office tower on the site. To be known as Chifley South, the new tower will add more than 50,000m² of premium grade NLA commercial office space, while a new seven-storey podium will integrate the new building with the existing Chifley North tower. In preparation for this development, A.G. Coombs has been engaged by main contractor Built to design and construct a central mechanical services plantroom that will serve both the existing tower, and new buildings. The 1,055m² plantroom space, constructed in the existing basement carpark, accommodates eight centrifugal water-cooled chillers – six main-load chillers with a capacity of 2.5MW each and two low-load chillers of 1400kW each. Each chiller set is served by two condenser and two chilled water pumps, all in duty-duty arrangement.
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Building Efficiency
A small 50kW after-hours chiller and associated fan coil units maintain conditions in the new plantroom. The tower’s existing cooling towers, which have been upgraded, will provide heat rejection until the new cooling tower plant is constructed as part of the Chifley South development. After becoming involved in investigation works during the tender process and identifying the latent conditions in the existing building, A.G. Coombs developed an alternative methodology for the connection of new chilled water and condenser water pipework into the HVAC system serving the Chifley North tower. To avoid disruption to tenants, pipework connections and cut-over works have been carefully planned and completed during long weekends when building occupancy is at its lowest.
Additionally, spatial restraints in the plantroom – combined with the size of pipework required to meet necessary flow rates – has demanded precise planning of pipework reticulation and assembly on site. Practical completion of the new central plantroom is expected by early 2024 ahead of the future development commencing. “A.G. Coombs’ active role in rationalising the new mechanical service plant design, and the team’s ability to complete potentially disruptive works on time while minimising the impact on tenants, has been of great benefit to the project,” says Marty Brooks, Project Manager at Built.
Coordination of services with other trades has also been critical, with A.G. Coombs taking the services lead on the project. “It is a complex and unique project in that the existing tower does not have any pressure breaks,” says Patryk Dykas, Project Engineer at A.G. Coombs. “Main chiller plantroom located on the bottom of the building is exposed to pressure of 2800kPa. All equipment, pipework, couplings and valves are required to be rated for this high operating pressure.”
2023-2024
commercial
Central to the redevelopment of Charter Hall’s Chifley Square precinct in Sydney’s CBD is the construction of a new central mechanical services plantroom.
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