As a construction material, wood can do something competing materials can’t: wood grows back, steel and concrete don’t. Wood grows more than we harvest in our forests. Additionally, CO2 is absorbed in growing trees, where it stays through harvesting and the wood product’s lifetime.
Wooden buildings store carbon for decades, or even centuries, keeping carbon dioxide out of the atmosphere where it could add to global warming. And when a wooden building is taken apart, it is not waste but a recyclable, reusable material, still storing carbon. The carbon content is only released into the atmosphere as CO2 when the wood eventually decomposes, or is burnt for bioenergy. By then, new trees will have grown, and are ready to absorb that CO2 back in.
Building with wood brings many advantages. The manufacture of timber produces considerably less CO2 than steel and concrete. The use of massive wood such as pre-fabricated CLT and LVL elements significantly reduces the carbon footprint of a new building frame. In logistics, timber weighs less than reinforced concrete, which allows timber to be transported by fewer trucks or railway, thereby reducing transport-related emissions. Additionally, building with wooden elements can reduce construction time, site waste and noise.
In northern and central European markets, the number of multi-storey apartments made with a wooden frame is increasing, both as a total and as a percentage of new construction. In Sweden, for example, the number of new apartments built with a wooden frame increased by around 5% from 2015 to 2016.
So far, the tallest building in the world with a wooden frame, currently under completion, is Mjøstårnet in Norway, rising 66 meters and 17 stories and hosting offices, hotel rooms and apartments. The Japanese “W350” project is on the drawing table, a proposed 70-storey skyscraper with wood making up 90% of the construction material.
New innovative solutions in massive wood make it possible to use wood in high-rise buildings and city centres. Massive wood elements made from a light but strong wood open the way for taller wooden high-rise buildings than ever before.
The Light House Joensuu is an excellent example of how high-rising construction can be sustainable and quickly implemented.