International House is a gateway project in more ways than one for its owner and developer Lendlease. Situated at a pedestrian entrance to a new mixed use precinct at Barangaroo on Sydney’s waterfront, the seven-storey building consists of six above-ground levels manufactured entirely from engineered timber supported by a single ground retail level of conventional concrete structure.
I had the privilege of visiting this building while it was under construction in August 2016. It was a surreal experience to be standing on the fourth floor of a commercial tower and to realise that it was essentially complete. But for the lack of the glass facade and the floor coverings, the tenants could have moved themselves in that day whilst the floors above were still coming together like Meccano. No need for plasterers and painters and months of ‘making good’. The building was all skin and bones, unadorned, and it was great.
The exposed timber structural columns, en masse within an open plan floorplate of over 1200 square metres, form a rhythmic cadence reminiscent of the forest their raw material was sourced from. Combine the columns, the walls, lift shafts, bracing and ceilings, and there’s a lot of wood on show. It’s mainly Austrian spruce but recycled Australian hardwoods are also used in places such as the stairs and in the giant bough-like supports for the retail colonnade at street level. Given the positive effects of hanging around in wooden buildings, which include lowered blood pressure and heart rate and increased sense of wellbeing, this must be a very zen place to work.
It was a brave move on Tzannes Architects’ part to elect not to conceal the services. Instead they are all expressed – painted a unifying matt black – running across ceilings, down walls and through penetrations in the LVL beams. Those penetrations were planned early in the design process and precision-cut in the factory, avoiding clashes and keeping the structural integrity of the building intact. It’s scrupulously neat, honest, and I imagine, a dream for property managers when something needs fixing. No gib to saw through looking for the source of the issue, then repair and paint later.
Ceiling heights of 2.7m were determined by planning rules, not constraints related to the materials. The 6x9m grid is derived from the optimal spans of the timber for workspace planning.
One of the things that struck us as we stood on the site that day was how quiet it was. Here we were in the middle of a large construction site and there was very little noise and no dust or mess to speak of. Given that the building is sited at a bottleneck that channels 33,000 pedestrians per day into a shopping and hospitality precinct, the minimal disruption was a gift to the people of Sydney. Eight guys were on-site, two at street level and only six above ground to put together the prefabricated elements of a 6,700sqm building. Despite the spartan crew, Lendlease’s project manager who was showing us around, said the 11-month programme would be half that of a conventional build.
Apparently the project was originally intended to be built with a concrete frame. During the development of the design, engineered timber was substituted on an equivalent cost and building height basis. The building uses around 3,500 cubic metres of sustainably grown and recycled timber. By not using concrete, thousands of tonnes of greenhouse gases have been avoided. For every tonne of concrete formed, half a tonne of CO2 is produced. Conversely, a single tree can absorb one tonne of carbon during its growth and sequester it within the timber. There it remains when the raw timber is turned into a building material. In fact, there it remains unless the timber rots or burns, neither of which are likely or easily achieved with engineered timber (but that’s the subject of a future blog).
Engineered timber buildings can be dismantled and the materials recycled. However, Lendlease has designed and built International House with longevity in mind. In the words of architect, Alec Tzannes, they reached for a design that would “weather well, be long lasting and attractive” because “buildings that are not considered beautiful tend to be demolished, so beauty is at the essence of our concerns about a lower carbon future.”
International House, although a relatively small project by Lendlease standards, has huge significance for the Australian-born multinational. The commercial space in the building was heavily oversubscribed, the architecture has won numerous awards at a national and international level for its design and green credentials, and the sustainability story has been a PR triumph for the company. International House represents the closest net zero emission construction that has been achieved to date for commercial building in Australia, completed to A-grade standards.
Most critically, in my view, they’ve demonstrated that mass timber construction is a viable alternative to conventional concrete construction for the commercial real estate market, and that occupiers will embrace a building that smells like Christmas. In fact, anecdotally, hugging the columns at International House is not uncommon.
Lendlease backed themselves to build in a better way and it has paid off.
The company has recently lodged a planning application for a sister building to International House on a neighbouring site at Barangaroo. There’s no reason we can’t build something of this scale and quality in New Zealand. We have the materials and the know-how. We just need the will to change the game.