ADVERTORIAL Sawmilling SA
Taking timber to new heights
A report by global design, engineering and architecture firm Arup, Rethinking Timber Buildings: Seven perspectives on the use of timber in building, states that global carbon dioxide emissions have increased by almost 50% since 1990, with the global construction industry alone producing around 15% of these emissions. Furthermore, an estimated two billion square metres of new building stock are needed every year between 2019 and 2025, especially for housing.
When you consider the findings of the more recent Intergovernmental Panel on Climate Change Assessment Report which states that climate change is widespread and rapidly intensifying, the built environment holds the mantle for sustainable and swift climate action. How? By using more wood. For many years, wood has been viewed as an inferior building material reserved either for the very poor or engineered for the ultra-rich. It’s been labelled a fire hazard, weak or the cause of deforestation.
Aiming high with a lower footprint
Many people associate wood with rudimentary shelters or ‘wendy’ houses; for some it’s a luxurious log cabin nestled on a hillside with a view of the ocean. But for professionals and architects who are drawn to the wonders of wood, the sky is quite literally the limit. The presence of wood even makes us feel better due to ‘biophilia’, a hypothesis popularised by biologist and author Edward Wilson. As humans, we have an innate tendency to seek connections with nature and other forms of life. The world’s tallest mass timber building is the 18-storey Brock Commons Student Residence in Vancouver, Canada. In 2018, Sumitomo Forestry announced its plans to build a 70-storey hybrid timber skyscraper to mark its 350th anniversary in 2041. Dubbed W350, this lofty tower of lumber reflects a growing global trend to take wood to new heights in the built environment.
Green cred
But mention of timber buildings, and most people think ‘deforestation’. Roy Southey, Executive Director of Sawmilling South Africa, says: “There is no doubt that concrete, steel
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and stone are good building materials, but it takes something special to match wood’s environmental credentials.” South Africa has 1.2 million hectares of farmed trees, and only 10% is harvested and replanted with new trees each year. This makes sustainably produced wood a renewable resource. The consumption of sustainable wood can actually help combat deforestation and local plantations are managed to stringent environmental criteria, especially in terms of water and biodiversity impacts. Sustainable forestry maintains trees in an active growing phase, optimising carbon storage. By harvesting small tracts at the right age, there is reduced risk of releasing carbon back into the atmosphere due to disturbances such as disease, decay and fire. Carbon is stored for longer when the trees are harvested and used for the production of wood products. Some 0.9 tons of carbon are sequestered by one cubic metre of wood throughout its lifetime. With a timber to steel ratio of 9:1, Sumitomo’s timber titan of 185 000 cubic metres will be a vault for 166 500 tons of carbon.
Timber ticks the boxes
Engineered wood types, such as glued laminated timber (glulam) or cross laminated timber, can match well with concrete and steel, with their competitive strength-to-weight ratios. “Along with design flexibility, longevity and superior insulating properties, timber structures are often prefabricated off-site and lighter to transport, reducing both construction times and associated costs,” points out Southey. Wood, of course, is a natural product and is thus susceptible to biological degradation. Biological degradation can occur
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