Wooden skyscrapers may help in slowing down global warming, but they are so much more

UNBC’s Wood Innovation and Design Centre is entirely out of wood, proving the potential of high-rise wooden buildings that have the added benefit of sequestering carbon. Photo credit: Ema Peter

Large timber constructions are not only getting taller, stronger, and safer. They may also help us cool the planet and slow down global warming.

In Prince George, Canada, the Wood Innovation and Design Centre at the University of Northern British Columbia (UNBC) is an eight storey building standing 30 metres high – and constructed almost completely from timber in 2014, making it one of the tallest wooden structures in the world.

In total, with the construction of the Wood Innovation and Design Centre the university managed to avoid releasing over 400 tonnes of carbon dioxide into the air by forgoing energy-intensive steel and concrete, as well as sequestering an additional 1,100 tonnes of carbon dioxide from the atmosphere; the equivalent of offsetting the emissions from 160 households a year.

Building with wood has its roots in ancient times, but it is only in the past twenty years that architects, engineers, and scientists have begun to recognise its potential ability to hold off global warming. According to research conducted by Chad Oliver, a forest ecologist at Yale University in New Haven, Connecticut, United States (U.S.), the construction industry can curb up to 31 per cent of global carbon emissions by substituting steel and concrete with timber from sustainably managed forests. With enough time, enough carbon dioxide can be pulled from the atmosphere to potentially start reversing climate change.

“It’s the plywood miracle,” Christopher Schwalm, an ecologist from the Woods Hole Research Centre in Falmouth, Massachusetts, U.S., said to Nature, the international journal of science. “This is something that could have a significant impact on the riddle that is global environmental change.”

Already, there is a resurgence in the construction of tall wooden buildings: In 2015, Norway set a world height record for wooden buildings with a 52.8-metre tower; in September 2016, the 53-metre student dormitory, Brock Commons, in the University of British Columbia, Vancouver, Canada, broke that record with other tall wooden buildings up in Portland, Oregon, and in the pipeline in New York City; this year, Austria is set to break Brock Commons’ record with the 84-metre HoHo building in Vienna.

In recent times, political interest in wooden construction has heightened, mostly due to the economic benefits for the communities surrounded by woodland. However, turning this pioneering trend into a global movement will not be easy: Building costs, more often than not, are high, and the global construction industry relies heavily on concrete and steel, especially when it comes to big and tall buildings.

Additionally, the benefits of building with wood that can be given to the climate are all dependent on the assumption that the forests the timber is harvested from are sustainably managed. Harvesting timber, especially those in developing countries afflicted by illegal logging practices, can negatively impact forest ecosystems.

As Oliver put it to Nature, “If we’re going to cut wood, we’ve got to do it in a way that not only sustains the forest but also sustains the biodiversity and everything else.”

Image credit: Nature


The strength of timber
When Buddhist monks completed the pagoda at the Learning Temple of the Flourishing Law in Ikaruga, Japan – 32 metres high – in 607, steel and concrete were simply not options. Instead, they placed their faith in wood. Four centuries later, in 1056, when they built the Sakyamuni Pagoda in Yingxian, China, the monks reiterated their trust in wood, constructing a marvel that rose 67 metres high, a massive achievement realised a millennia ago.

The fact that both these pagodas still stand tall today is nothing less than a tribute to the durability, endurance, and strength of wood. As a building material, they are stronger than steel and concrete, with the added advantage of being far better at withstanding earthquakes. But wood has gained a poor reputation over the years, due to the devastating blazes that ravaged cities such as San Francisco, London, and Rome before modern fire-suppression strategies came into being.

As a matter of fact, fire wood maintains its structural integrity much better than non-flammable alternatives modern building codes favour. While it does char at a rate that is predictable, it does not weaken like concrete, or melt as steel does.

“The fact that it actually can withstand fire better than steel took a long time for people to realise,” Guido Wimmer, chairman of a master’s programme in wood engineering in UNBC observed.

According to Nature, the current era of tall wooden buildings that we are living in now began some two decades ago, where researchers in Austria’s Technical University of Graz conducted a simple experiment that resulted in the discovery of cross-laminated timber (CLT). Produced by gluing layers of standard planks perpendicular to each other, the alternating directions of the grain negate the failings and weaknesses of any individual plank – and put the strength of conventional plywood to shame.

Additionally, it can be cut to sub-millimetre precision or created as large as is needed in the factory, hastening construction and lowering waste. With the strength of these engineered panels, there is no theoretical limit to how high wooden buildings constructed of these materials can go.

“It transforms wood from a suburban material to a very urban material,” Michael Green, the architect behind UNBC’s design centre told Nature, and one of the foremost advocates for wooden buildings.

But in the long run, the economic viability and performance of these wooden structures are still an open question. Wood is vulnerable to mould and water damage, to name a few, and there will be a higher risk of fire during the time of construction. For instance, in September 2014, a wooden sustainable chemistry building under construction at the University of Nottingham, United Kingdom (U.K.) was levelled by an electrical fire, mostly because the fire doors and windows had not been in place to contain the element.


Carbon sequestering
One of the main benefits of building with wood is that by sequestering carbon, it helps to ameliorate climate change and global warming. Oliver’s research suggests that humanity only harvests approximately 20 per cent of global forest growth annually, and more timber can be extracted without lowering the overall amount of carbon forests have sequestered away.

Even if the wood was simply burned for the production of energy, the carbon dioxide the tree had absorbed earlier over the years released back into atmosphere, allowing the forests to re-grow will gradually pull that carbon dioxide back in and out of the air and thus making the concept of carbon-neutral wood energy a function of time.

“Just the fact that you have solid wood means that you are keeping carbon dioxide out of the atmosphere,” Oliver stated.

Even without including the carbon sequestered in the wood, construction with wood gives more than emissions savings. According to Nature, when researchers calculated the environmental impact of UNBC’s Wood Innovation and Design Centre, they accounted for the transport and manufacture of every material used, all the way down to the glue – gleaned from fossil fuels – that bound the plywood together. On a whole, the emissions associated with the construction of the building was 12 per cent of what would be emitted from the construction of a concrete building, mostly due to the vast differences in the usage of fossil fuels.

“When you compare a wood building with a concrete building, wood wins every time,” Jim Bowyer, an emeritus engineer from the University of Minnesota in St Paul, said to Nature.

UNBC’s Wood Innovation and Design Centre might boast an extraordinarily low carbon footprint at the beginning, but over time, its environmental impact will nonetheless grow as its cooling, heating, and lighting requirements generate and emit greenhouse-gases. Daily use of energy and maintenance of the building produce 80 to 90 per cent of the total lifetime emissions for a regular building, and the Wood Innovation and Design Centre is unfortunately not exempt from that. As a result, the benefits it brings to the climate over the long term are relatively modest at best.

Fortunately, cutting-edge buildings today integrate on-site renewable energy generation with energy-efficient designs and technologies to remove emissions over the structure’s lifetime. In such cases, the embodied emissions from the building’s construction materials – which make up 100 per cent of the structure’s impact on the climate – will give wood an important edge over other building products.

“We’re moving towards really low-energy buildings,” Jennifer O’Connor, president of the non-profit research organisation based in Ottawa, Canada, Athena Sustainable Materials Institute, told Nature. “Quite frankly, if we are going to make a difference, then we had better start looking at those embodied emissions.”


Playing a long game
Presently, the movement for building with wood is concentrated mostly in North America and Europe. According to Bowyer, more than 80 per cent of houses in the U.S. are already wood-based. However, with the country’s timber industry extracting approximately a third of total annual forest growth, there is room to expand wood construction to mid-rise commercial and industry buildings without bringing down the volume of carbon currently held in the forests.

Bowyer is spearheading an expert assessment mustered by the American Wood Council, an industry body based in Leesburg, Virginia. Already, the team had found that the U.S. has the ability to roughly double the amount of sequestered carbon in buildings a year, thus negating the emissions from nine additional coal-fired power plants.

In contrast, European builders still rely heavily on concrete and steel. But in 2010, the Finnish government published a report estimating that a small four per cent increase per year in construction with wood throughout the nations in Europe will avert 150 million tonnes of carbon emissions – an amount almost as much as what the Netherlands emits a year.

But to have an impact that can be felt from all corners of the globe, the movement has to expand to developing counties, where forest management remains an uphill battle. Tropical forests are ravaged and wiped out for agriculture. For example, Indonesia has struggled time and again to bring the palm-oil industry’s demolition of rainforests to a halt, and in Brazil, while huge leaps have been made in forest management over the past ten years, growing demand for beef and soya beans are once again leading to land-clearing in the Amazon forest.

Fears that rising wood construction will negatively affect some of the world’s most valued ecosystems are also increasing. “I’ve seen enough abuses of what you would call the wood-product sector that I’m leery of sweeping solutions that make big assumptions,” William Laurance, a tropical ecologist from James Cook University in Cairns, Australia, said to Nature.

Oliver, however, sees wooden construction as an opportunity for developing countries to establish sustainable industries that protect forests, especially if they are sought alongside efforts to boost governance. The challenge is that vital ecosystems in the managed forests must be protected and secured, including forest clearings and old-growth habitats.”It should all be pre-planned and transparent,” Oliver stated. “That’s kind of a utopia, but you’ve got to dream.”

Now, he is working closely with the United Nations Development Programme (UNDP) to devise an extensive and comprehensive forest-management plan that would initiate modern construction with wood in Turkey. Government figures show that the nation brought up 956 million sqm of building space in the decade between 2004 and 2014, but only 0.13 per cent of that total was framed with wood. Yet, according with Nuri Özbağdatlı, UNDP’s expert in forestry in Ankara, Turkey, 27 per cent of the nation consists of forested land, and seven million of Turkey’s poorest citizens reside in those areas. “We want to create a new value chain for wood,” he explained to Nature. “It will start with the forest villages and end up with the construction sector.”

As the wooden construction industry continues to mature, it will be faced with one final obstacle: What will happen when a building is decommissioned and torn down. Buddhist pagodas have the ability to last for centuries, but the general assumption that dogs many modern buildings is that one day, when they have outlived their usefulness in a few decades, they will be replaced.

If the wood is dumped and left to rot, the carbon it has sequestered away will slowly leak out and rejoin the atmosphere. But if the wood is reused and recycled, the benefits to the climate will remain locked in the wood.

Wood advocates are promoting long-term strategies that include recycling and various other carbon-neutral choices, but according to Green, if properly maintained, there is no reason why a wood building cannot stand as long as a Buddhist pagoda. It is just a matter of understanding wooden construction. Green said, “This is the only hope of accelerating this to be competitive with concrete and steel, which have a 150-year head start.”


Source: Nature