Melbourne developer James Dibble has submitted plans for the world’s tallest hybrid timber building in South Perth. 

Standing at 183-metres, the $350 million apartment block will be titled C6, after the periodic table’s symbol for carbon, and will be located at 6 Charles Street close to the Perth Zoo.

It will include about 7400 cubic metres of timber in its construction, making up almost half of its total structure at 42 per cent, plus steel, concrete and other materials.

Grange Development teamed up with architectural firm Elenberg Fraser, as well as engineers Vistek Structural Engineers and Norman Disney & Young, to develop the concept.

If it is approved, the building will be Australia’s second carbon-negative building after the Atlassian tower and stand three metres taller. It will achieve this through an embedded power network with wind and solar power, and a biophilic design featuring 3500 square metres of floral, edible and native gardens.

The Grange Development apartments will include 245 one, two, three and four bedroom apartments over 48 levels, an open-air public piazza and an entertainment precinct. Construction will begin at the end of 2023 with a two year time frame. 

The tallest standing building in the world is currently Mjøstårnet in Norway, with 18 floors and 85.4 metres. The tallest hybrid timber building currently under construction is Ascent Milwaukee in Wisconsin, USA, which will be 87 metres tall once completed. As you can see, C6 will cast a shadow over its contemporaries. 

Buildings made from engineered timber have a significantly lower carbon footprint than other structures, both during construction and operation. Construction of the building’s core will sequester over 10.5 million kilograms of carbon dioxide, compared to a traditional concrete structure of similar scale.

“The built environment is one of the three major drivers of catastrophic climate change, alongside transport and agriculture,” said James Dibble, founder and director of Grange Development. 

“The property industry is lagging dangerously behind.

“If we get this right, we should never have to rely on building another solely concrete or steel tower in our lifetime.”

Robert Svars, the general manager at Vistek Structural Engineers (which was responsible for the timber part of the engineering), said that the building would be a beacon for others to follow. 

“No one is really making inroads in construction at the large and dramatic pace that needs to happen,” he said. 

“Timber as a building material has been around for centuries, but only recently has mass timber construction and fabrication methods made it a viable option en masse,” Mr Dibble said.

Principal architect Reade Dixon said that the hybrid timber design was a challenge.

“It is new ground for engineering at this scale, which is why this has never been done before.”

“It’s about managing the unknown unknowns and risk,” Mr Svars said. “All materials are widely used, but it will be a unique design process as we don’t have project precedents we can rely upon.” 

“When you mix materials, you have issues about concrete and wood behaving differently over time, with shrinkage rates and so on. Design must have constructability at the front of mind and take a holistic look, and the structural engineer must be hands on. Timber calls for integration with the architects. 

“Everyone has to work together.”

On the theme of working together, design decisions were made through close consultation with a fire engineer and local fire authorities. You might think a timber building would be likely to go up in flames, but Mr Svars says that is not the case. 

“It’s not necessarily an increased risk over conventional structures. But it’s a different risk. Timber doesn’t lose strength under heat, while steel does – dramatically.” 

Another challenge they are working on is the material sourcing to supply them with the mass of timber needed at such a large scale. They are looking at suppliers in Western Australia and Victoria. They are even conducting a transport carbon assessment to decide whether it might be lower carbon to ship from Europe. 

As for concrete, they are exploring whether it might be possible to use low carbon concrete to reduce embodied carbon in the building. 

“We are still exploring options to reduce embodied carbon in the building. We are looking at creating a better recipe,” Mr Dixon said. 

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  1. This is a debacle. Architects have fallen for a marketing campaign by the timber industry that is based on misquoting and misusing the science on timber production vs. carbon sequestration and greenhouse gas emissions. In the US, 97% of building construction is residential, the vast majority of which are single family homes, the vast majority of those being wood-framed. As if we’re not using *enough* wood in construction!
    And all this demand has been driving the destruction of forests, especially for conversion to fast wood plantations which, overall, have been shown to *not* sequester carbon in the long-term.
    The math used to say that they do is a mere snippet of a longer equation, where the original destruction of the forest is ignored, the loss of soil and root-mass carbon from successive harvests is ignored, what happens to the wood when buildings are demolished is ignored, and the loss of biodiversity is (which has also been shown to be a significant factor in carbon flux) is ignored. In fact, a graph of carbon flux for a site going from natural forest to fast wood plantation, into numerous harvest cycles shows a significant flux of positive emissions — even without the methane emissions generated from the landfill disposal of harvested wood products. Fast wood plantations don’t recover the carbon lost from initial clearing; forests have to reach 150 years or more before they start recovering the lost carbon.
    If the overall management system yields a positive flux for carbon emissions, it makes zero sense to focus on a narrow clip of the equation that might show a brief negative flux. In truth, one is getting nowhere and even going backwards.
    Indeed, one recent study showed that the last 70 years of ‘forestry’ in Europe (that is, repeated harvesting of fast wood plantations, with continued conversion of what little natural forests are left) has had no positive effect on climate change mitigation. That is, overall, it’s not yielded on molecule of carbon sequestered from the atmosphere back into the land for the long-term.
    All this additional demand for wood will lead to even more clearing and conversion of natural forests, which are needed to continue to sequester carbon. One thing that we *must* do to sequester carbon is leave natural forests alone to sequester more. Older forests have been shown unequivocally to sequester more and more carbon as they age. We also need a massive, global program to restore natural forests where they were, and help that along with natural techniques, such as applications of plant-based wastes (for instance, applications of coffee grounds have been shown to greatly speed recovery of cleared forests in the tropics).
    in the meantime, we need to build less, use only 100% post-consumer recycled materials (such as steel, aluminum and plastic), eliminate our use of single-use paper products). We need to give natural forests a break, adhere to Slow Wood™ criteria, and reduce demand for wood products — not increase it!

  2. There is an alternative to timber from trees, is still a timber, is stronger than timber AND steel AND concrete, and more sustainable than timber from trees. Bamboo locks up 38 times more CO2 and grows 78 times faster than trees. See here for a new design method using engineered bamboo.