TALKING TIMBER
Wood is good
Compiled by Leon Louw
Can you imagine a 350-metre-high skyscraper made mostly from wood ? Sumitomo Forestry can . The Japanese company plans to build one in Tokyo to mark its 350th anniversary in 2041 .
This ambitious undertaking reflects a growing global trend to take wood to new heights in the built environment .
“ Mention timber buildings , and most people think of ‘ wendy houses ’ or log cabins . They think ‘ fire hazard ’. They think deforestation ,” says Roy Southey , executive director for Sawmilling South Africa ( SSA ).
In fact , the opposite is true , he says . The consumption of sustainable wood can help combat deforestation . Well-managed planted forests ( plantations ) reduce soil erosion , maintain the water balance in the surrounding areas and provide refuge for an array of species , thereby preserving biodiversity .
GOOD FOR THE ENVIRONMENT
Trees are nature ’ s biggest carbon sinks . As they grow , they absorb ( sequester ) carbon dioxide and store it as carbon in leaves , trunks , roots , and soil .
“ The procurement of renewable , sustainably produced wood by the construction sector holds the greatest potential for climate change mitigation ," says Southey .
Some 0.9 tonnes of carbon are sequestered by one cubic metre of wood throughout its lifetime . With a timber-to-steel ratio of 9:1 , Sumitomo ’ s 70-storey tower will require 185 000 cubic metres of wood , acting as storage for 166 500 tonnes of carbon .
Closer to home , South Africa has 1.2 million hectares of farmed trees which sequester around 64.8 million tonnes of carbon . These trees are planted , harvested , and replanted for the purpose of making sawn timber , pulp , and paper products , among other things .
When a harvested tree is made into a solid wood product or pulp for paper , the carbon remains locked up in those products . When the land is replanted with new trees , the carbon cycle begins all over again .
GOOD FOR BUILDING
Timber plantations represent 7 % of the planet ’ s forest areas yet provide 50 % of the wood for industrial purposes .
“ There is an exciting move by architects as they look to the forest products sector for carbon-neutral and renewable options ,” adds Southey .
Timber competes well with concrete and steel , in that it offers strength , can withstand seismic activity ( not such a big factor in South Africa ), and is much lighter to transport . “ Timber structures are often prefabricated off-site , reducing both the construction times and associated costs ,” he notes .
ANDERS VESTERGAARD JENSEN I UNSPLASH
More and more multi-storey buildings around the world are being constructed with timber .
20 JUNE / JULY 2021 // www . timberiq . co . za