Physics says a skyscraper can be made of wood. There are also some good reasons it should be. Handled properly wood can be the most ethical and sustainable building material there is. And no, fire isn't a deal breaker
Standing side-by-side in Sydney’s Barangaroo precinct are two new office buildings that are part of an international architectural revolution. What makes them unique in Australia and uncommon around the world is that they are commercial buildings made almost entirely out of wood. Walls, floors, ceilings, roof, lift shafts and stairwells, all made of wood.
The architect who has put hundreds of hours of his life into creating these buildings is Jonathan Evans. A gently spoken man, he wants his wooden buildings to be a strong statement about a better way of doing things.
“We were looking for a renewable material that could build our cities, not just our homes,” he says. “We want to bring our cities more into a natural cycle with the environment.”
Go to a high vantage point and view a modern city and what you see is, in effect, a vast landscape of concrete and steel. In a carbon-aware world, most people know that steel production is energy-hungry, but the lesser known but much bigger villain is cement.
Producing a ton of cement sucks in the energy equivalent of more than 180 kilograms of carbon-heavy coal. A necessary chemical reaction in the process also produces huge amounts of CO2 so overall, nearly a ton of CO2 enters the atmosphere.
To understand the implications, consider that cement is the second most used substance on Earth after water, and if the cement industry was a country, it would be the world’s third largest emitter. This makes cement a problem. Wood could be part of a solution.
“We do require shelter,” says Evans who even as a child roaming the bushland around Newcastle, knew he wanted to be an architect. “So why not make our shelters beautiful and generous and connected and harmonious with nature?”
Evans has developed his more human-focussed approach to architecture over his 22 years as a director in Sydney’s highly regarded, boutique architecture practice, Tzannes (Founding Director, Alec Tzannes is also an alumnus). On turning 40, Evans decided to extend his thinking with a Master of Design Science in Sustainability, “Now I’m taking what I learned in theory and through research to the industry,” he says. “But people can be suspicious of architects selling a dream.”
Luckily, Lendlease, the property and construction company developing the Barangaroo precinct, weren’t suspicious. They welcomed the level of ambition and what the idea of a wooden building offered.
While Evans wants to see the substance of future cities change dramatically, those cities may not look all that different.
Based on physics, there is no reason why a wooden building can’t be a skyscraper. In fact, a word already exists for it; plyscraper. In Norway, there is an 18-storey wooden hotel, and the Sumitomo Forestry company in Japan, plans to celebrate a future anniversary by building a 70 storey all-wood building in Tokyo; a true vote of confidence in the robustness of wood, considering Japan’s seismic disposition.
Evans is dubious about some of the other more show-pony projects being announced internationally, “It can be green-spin,” he says. But in terms of industry world best practice, Evans’ Barangaroo buildings, International House Sydney and Daramu House stand as multi-award winning examples.
The Barangaroo locals probably noticed how different those sites were from their steel and concrete counterparts. With fewer concrete truck deliveries and mixers, they were certainly quieter. The only concrete used is for plinths which are the points of ground contact, preventing termites and damp rising into the wood.
And for those concerned by the fire risk, you’re certainly not alone. It’s a question Evans has answered often.
“We went through every challenge that timber might present,” he says. “The CSIRO and others have tested the burn rate of the timber, and ultimately, the building needs to achieve the same fire performance as any other form of construction. NSW Fire and Rescue were given all the available testing data and analysis and gave the project their tick of approval.”
Since the wooden elements were delivered precisely pre-cut, there was less noisy on-site drilling and cutting. The sites were also tidier and less hazardous because there were no piles of raw materials sitting around or being worked on, and nearly no waste.
Construction also happened more quickly. Piecing together pre-cut building elements is faster than mixing, forming and reinforcing wet concrete, then waiting for it to dry and achieve strength. Are the elements of a wooden building more expensive than concrete and steel? Yes. Is wood construction more expensive? It’s actually possible to build more cheaply by maximising the benefits of pre-fabrication.
“You can get off-site 3 months quicker. That’s a lot of money saved there,” says Evans. “Not putting in ceilings and wall finishes because wood is an attractive feature, is another cost and material saving.”
At the centre of this work, is what’s called engineered wood. It exists in a number of forms, but Evans used two types for the Barangaroo project; Cross Laminated Timber (CLT) and glue laminated timber (Glulam).
They were produced in a largely automated factory in Austria, where CLT was invented in the 1980s. The factory uses only farmed softwood from nearby forests and it glues the relatively short and thin pieces of timber into a cross-layered and super-strong product. Evans describes it as ‘infinity long’, like an endless tree truck that can be cut to any length with virtually no waste.
“It’ll attract more investment and more jobs and trigger the planting of new forests to take up more carbon dioxide.”
Provided with an information-dense 3D building plan, the factory produced the exact lengths of CLT specified, with all ducts and other necessary access points incised, ready for a huge, flat-pack delivery to Sydney. Of course, Evans would have liked it all to happen in Australia, and that is now a possibility, with an engineered wood factory recently opening on the border of NSW and Victoria.
“Plantation softwoods can grow fast in plenty of areas around Australia,” he says. “With so many of our trees becoming low value woodchips, they could instead be redirected into these multi-million dollar buildings. It’ll attract more investment and more jobs and trigger the planting of new forests to take up more carbon dioxide.
When people in the future go to a high vantage point to view their city, Evans and others like him, want them to see a vast landscape of buildings that are like a massive, repurposed forest locking in enormous quantities of carbon. An environment built of carbon, rather than producing it.
“I’ve always thought we’ve left behind what nature could bring to our cities,” Evans says. “Maybe now, we’re finding our way back.”
Written by George Dodd
Photographs of Jonathan Evans by Louise M Cooper