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On a prime corner at the ‘Paris’ end of Collins Street in Melbourne’s CBD, the T&G Building underwent a refurbishment that brought the historic neo-renaissance 1920s building into the 21st century.
A Melbourne icon, the renovation and modernisation of 161 Collins Street’s 10 storeys of commercial space has created a world-class office environment. Working with architects Bates Smart, Arup provided multidisciplinary engineering to redefine the confusing multiple entrances to create clear central access and create 4,000m² campus-style floor plates designed around the upgraded atrium.
Positioning for potential upgrade
Arup undertook a due diligence survey of the property for Pembroke as part of its purchase of the building in 2015. With Bates Smart, Arup identified potential upgrade options while the building was tenanted which would reposition it as A Grade space, improve energy performance and deliver high quality space and improved amenity.
Increasing visibility and permeability at street level
A focus of the refurbishment was increasing visibility and permeability at street level by removing portions of the structure at each of the three main entrances. Three major transfer structures were introduced, one on each elevation, to realise the full potential of the redevelopment. Due to the unique nature of each area, different transfer structures had to be optimised. Staging of works, particularly completion of transfer structures, was critical to maintain the construction programme.
Project Summary
4.0Star NABERS Energy rating upgraded from 3 Star
4,000m2 campus-style floor plates
42,500m2 net lettable area
“Together with Bates Smart, our targeted engineering interventions have brought to life Pembroke’s vision for the building, reduced its environmental impact and futureproofed it to compete with the next generation of building stock. ”
Nick Adams Melbourne Building Services Leader
Giving space back to pedestrians
The most ambitious transformation was the Flinders Lane/Ramsden Lane entrance. Previously a carriageway to the basement level carpark, Arup’s structural engineers designed for the alteration of the entire southern entry point, where more than three floors of boundary wall were removed to create a new pedestrian entry. Some 300m2 of floor area were demolished across two levels to create a three-level void at the southern façade, with the boundary wall demolished for this opening. An existing light well lends natural light to the space and enhances the connectivity between Collins Street and popular Flinders Lane.
Upgrading assets and improving energy efficiency
As part of the upgrade, all major, ageing mechanical plant systems were assessed for condition and performance. Plant equipment at the end of its life or no longer energy efficient was replaced, including central chiller and boiler plant. On-floor works were minimised to reduce impact on tenants, with the works focused on replacing existing fan assisted, electric reheat VAV boxes with an efficient low temperature VAV system. This improved thermal comfort for tenants and enabled air handling unit air flow rates to be cut, greatly reducing energy consumption.
The acoustic design also mitigated unwanted noise from plant equipment and services. We also replaced all lighting, halving lighting power density.
These works significantly improved energy performance, lifting the NABERS Energy rating from 3-stars to 4.0-stars, while the works also resulted in the building achieving a 3.5-star NABERS Water rating.
Designing a WELL ready building
A key feature was providing a WELL enabled building for tenants. The base building design was informed by the WELL Silver Core and Shell v1 rating tool, which led to implementing a range of health and wellness features. These included high-grade filtration to air handling units, post construction testing of air and water quality and best practice levels of thermal comfort. Redundant air risers were repurposed for outside air and exhaust systems, improving air quality on floor.
Meanwhile, Arup’s facade team designed a new ‘skin’ for the atrium interior with highly transparent replacement glass that removed obstructive fins. This enhanced daylight and views, making the most of the unique full height atrium at the building’s core.
Arup’s team also worked with the project team to deliver an action plan so that wellness features were maintained during the ongoing operation of the building. It was also brought up to modern tenancy expectations by adding significant end of trip facilities including 16 showers and 194 bicycle racks. There are new club-style concierge services for tenants.
Supporting multiple tenancies
Arup’s team has also supported several fitouts within the building including Regus, Google, Treasury Wine Estate, GFG Alliance, Bottega Veneta and two high end food and beverage tenancies for the Mulberry group. The success of the redevelopment is highlighted by the calibre of the clients which have taken space in this iconic building with large 4,000m2 floor plates being adapted for their specific needs.
Modification to the tenancies included the addition of intertenancy stairs by Arup’s structural engineers to create connection across two or more floor plates. These stairs were designed to work within the constraints of the existing structural system, and as required, localised works were undertaken to strengthen the base building structure to accommodate new stairs. The stair voids were bespoke solutions to ensure that buildability, architectural and structural considerations were all met to achieve the best outcome for the building and tenants.
