Trees ingest carbon while they grow and a primary source of this are the decayed limbs of dead trees. Once a forest is mature, it essentially sustains itself. Suffice to say, the sourcing, development and lifespan of wooden buildings is much, much closer to carbon neutrality than steel or concrete.
In the UK, between 15%-30% of new homes built annually use timber frame construction. This captures more than 1m tonnes of CO2 a year. Sustainability experts are now excited about the potential scale of carbon benefit if this is extended to the commercial real estate sector.
And scale is not a problem for wooden buildings – or more accurately, cross-laminated timber (CLT) – which layers strips of wood to create an extremely strong and, perhaps surprisingly, very fire-resistant material.
The trend is spreading worldwide: at 29-storeys, the playfully named, WoHo tower, designed by the Norwegian firm Mad Architects, will be one of the tallest wooden buildings in Europe, rising 98m over central Berlin (pictured above). Over in Japan, by 2024, Sumitomo Group hopes to use CLT to build a 70-storey wood skyscraper in Tokyo.
The concept is also being looked at in the UK. Architectural practice, PLP, has produced conceptual proposals for a 1m sq ft mixed-use tower and mid-rise terraces within the Barbican complex in central London that would rise to around 1,000 ft.
Of course, the resilience of tall buildings remains a sensitive subject in the UK following the Grenfell Tower fire of 2017. In what has been an unfortunate reaction, the Government has mooted proposals to restrict the height of wood-based buildings to just 36 feet tall. This might be understandable in the immediate aftermath of the Grenfell tragedy but is actually contrary to the facts about CLT. When exposed to fire, it chars and actually becomes stronger – unlike steel which warps and loses its tensile strength.
The sustainability benefits of creating a virtuous construction circle are clear and it would be a missed opportunity – from both a sustainability and safety perspective – if this mode of creating buildings was not more widely embraced.