Building the future with nature’s help
• Can wood buildings be part of SA’s climate change solution, asks Alf James
A quiet revolution in construction started about a decade ago in Europe and has now spread to North America and the rest of the world: the building of multistorey structures in wood, according to Brand Wessels, senior lecturer at the Department of Forest and Wood Science at Stellenbosch University.
He says in 2010 the tallest wooden building was completed in London — it was an apartment block of nine storeys. However, the current record holder is an 18-storey building in Vancouver, Canada.
“Prominent architects such as Michael Green from Canada and Michael Ramage of Cambridge University predict the 21st century will become known as the century of wood construction, similar to the 20th century being the century of concrete and steel skyscrapers.
“Some think that our cities of the future will be built nearly entirely from wood,” he says.
But what triggered this revolution? Wessels says first, the development of high strength wood structural materials such as crosslaminated timber, glued laminated timber and laminated veneer lumber. More importantly is the demand from society for environmentally responsible choices in all our materials and activities.
“This is where wood has a huge advantage over other materials. Trees absorb CO2 from the atmosphere. Most of the carbon is fixed in the tree in the form of wood, while oxygen is released into the atmosphere.
“Wood in buildings is, therefore, a type of carbon storage facility. Constructing a wooden building such as the 18storey residence in Vancouver is equivalent to removing 511 cars from the road in a year.
“A wood building can also result in energy saving due to its good insulation properties. Wood is 400 times better than steel and 10 times better than concrete (per volume) in resisting the flow of heat due to its low conductivity and good insulating ability, which can lead to significant energy savings,” says Wessels.
“Given that the construction and use of buildings is responsible for an estimated 27% of all CO2 emissions in SA, building with wood can play an important role in climate change mitigation.”
However, SA does not have a wood-building culture.
“We build less than 1% of our residential houses in wood compared to countries such as the US and Canada where more than 95% of residential structures are wood.
“The question is whether wood has a realistic future as a building material for South Africans? While this question will be settled by the developers and owners of buildings, the scientific community has a role to play in making sure information is available for users to make informed material choices, especially in terms of environmental impacts of materials,” says Wessels.
Finally, there is the question of whether there are enough wood resources in SA to sustain a significant share in the construction market. Wessels says recent modelling studies show we will be able to construct up to 20% of residential housing in locally produced wood-based materials. However, it will require significant changes in wood resource use in SA.
“There are several economic and technical challenges to make that a reality. But it is possible,” says Wessels.