Sydney’s wooden office building

We were very privileged to have Alec Tzannes, architect, speak to us at our June general meeting about the design and construction of Australia’s largest commercial building made from wood – International House at Barangaroo.

Alec is the founding director of Tzannes, an architecture and urban design practice. He is one of Australia’s most respected architects with a portfolio of private and public work spanning more than 30 years. His firm has won more than 100 local, state, national and international design awards. From 2008-2016 he was the Dean of the University of NSW Built Environment and is now an Emeritus Professor at UNSW. Within days of addressing us, the Australian Institute of Architects awarded Alec a Gold Medal, their highest honour, for his contribution to architecture in Australia.

But now to International House… It is located at the entrance to Barangaroo and is a seven storey commercial building almost entirely constructed from wood. Although mid-rise wooden buildings have been built in recent years for residential developments, they do not have large open floorpans. Designing and constructing a wooden building with 1,250sqm floor spaces without any internal walls is a different challenge entirely.

The construction almost did not proceed. Alec told the story of how Lend Lease, the developer, was persuaded to adopt the innovative design and how, to its credit, Lend Lease has commissioned further similar buildings.

Alec provided a fascinating exposition about the design considerations and process, the materials and construction methods utilised, and the sustainability of the building.

From a concrete base, the building is supported by a row of hardwood timber columns rising from metal plinths. The exterior is ironwood recovered from a wharf in Queensland.

The internal structure is a network of glued laminated columns (480x480mm) and beams (800x480mm) and cross laminated (CLT) slabs (12×2.25x.22m) of spruce, made in Austria as the process was not available in Australia at that time.

All the timber is renewable structural material with FSC certification. The timber volumes were 2,400m3 of glulam, 900m3 of CLT and 150m3 of hardwood – the equivalent of 1,840 spruce trees or 6 hectares of forest. Australian radiata pine forests can apparently grow International House in 2.5 hours! The building contains 50% less carbon than the equivalent concrete building. It took only a small crew to put the building together like a meccano set and it was a pleasure to work at the site during its construction.

Alec talked about the delightful smell of the spruce forest and the absence of concrete dust, noise and volatile organic compounds. This was confirmed by a friend who was a sub-contractor and worked on the project.

The benefits of having exposed timber and natural materials in a work environment have been well documented. Higher personal productivity has been demonstrated aswell as a greater sense of optimism and creativity with reduced stress and improved air quality. One of the other wonderful attributes of this building is that it can be completely dismantled and re-used. As the need and desire for sustainability in constructions increases, the ability to re-use materials has to be a core element of design.

International House won the prestigious 2017 Athenaeum & European Centre design award for international architecture and the Australian Timber Design Award. We congratulate Alec and his firm on their innovative and sensitive work and perseverance in designing this building and bringing it to fruition.

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