Fresh Thinking

Prefab-ulous

The clever use of prefabricated services modules as part of a major mechanical services upgrade to a commercial building in Sydney has the property well on its way to achieving ‘A’ Grade status.

Originally built in 1906, the former woolstore at 235 Pyrmont Street has become a much-sought after commercial address.

Featuring an internal design that melds the building’s heritage features with modern office amenities, the eightstorey building has been maintained by A.G. Coombs for a number of years.

With the existing base building open-circuit condenser water cooling plant approaching end-of-life, A.G. Coombs was successful in tendering for a design and construct (D&C) principal contractor role direct to owner Kador Group to revitalise the mechanical services.

The $4.5 million project included new chiller and boiler plant on the roof, and progressive works to be staged over a number of years to phase out the existing condenser water system to the new chilled water system.

“The client’s end goal was to have the mechanical services meet the compliance requirements of the Property Council of Australia’s ‘A’ Grade level,” says Gary Economos, General Manager for A.G. Coombs NSW. Central to A.G. Coombs’ tender were a number of value engineering initiatives that would reduce project cost and improve energy efficiency, including the offsite prefabrication of a drop-in rooftop plantroom constructed under COVID-safe conditions.

This approach required a number of modern construction technologies to be adopted, including building information modelling (BIM) and 3D point cloud scan that digitised the project environment.

The digitised construction model was also used to determine set outs for pipe supports, equipment plinths, new wall locations, new floor waste and skid plinths. These parameters were then set out on site using a Trimble laser to an accuracy of 2mm, significantly reducing the amount of time-consuming work required on site and limiting the noise disruption to neighbours.

The design of the modular plantroom was completed concurrently to the Development Application (DA) process, with offsite prefabrication commencing well ahead of the scheduled site start date.

Within days of the DA being approved, the three 6m x 3m plantroom modules were craned into place on the building’s rooftop. The application of digital tools and prefabrication also enabled A.G. Coombs to complete the installation of two chillers, three cooling towers and ancillary plant – as well as 80% of the pipework – within just a few days.

“This strategy de-risked the project in a number of ways, particularly given the uncertainty of the program with respect to the timing of Council approval, and avoided the delays that would have resulted from the introduction of COVID-19 restrictions,” says Gary.

Since the completion of the rooftop works in mid-2020, A.G. Coombs has continued working with Kador Group and project manager TSA Management to progressively refurbish the mechanical services across the building.

“As principal contractor, A.G. Coombs presented a clever, turn-key solution that overcame a number of challenges and will contribute to Kador Group achieving our ambitions for the property,” says Richard Poore, Manager of Development and Projects at Kador Group.