Built in 607AD in Nara, Japan Horyu-ji Temple is the world's oldest surviving wooden building. Five storeys high, it's still standing firm despite being made from cypress trees felled over 1,400 years ago. And Horyu's great age reveals a message for our future - building with timber can be durable, beautiful and practical and it can even help tackle climate change.
Here's why. If we made 90% of our new buildings from wood rather than concrete and steel we could reduce our global carbon emissions by 4%. That's more than the total climate footprint of flying.
So why does building with wood do such good? First, trees absorb carbon dioxide from the air as they grow. This is naturally stored in the beams and panels of buildings, a process known as carbon capture.
So the timber in Horyu Temple contains CO2 absorbed from the planet's atmosphere in the 7th Century. Of course, using wood means felling trees, but so long as you're not chopping down ancient forests, you're maintaining the wildlife, replanting, and putting wood to long-term use, it's sustainable. In the last 15 years, in the northern Hemisphere total forest cover has increased by an area of around 242,000 sq km, about the size of the United Kingdom.
In fact, every seven seconds the sustainable woodlands of Europe yield enough timber to build a four-person family home. And it's not just Europe - Canada can harvest enough trees every year to house about a billion people. An equally important carbon reduction comes from what you're not using - construction with natural materials demands far less concrete and steel and these are massive climate culprits.
Steel-making accounts for around 8% of total global CO2 emissions and cement accounts for a further 6%. OK, not all of this is going into buildings, but they are a big customer. It's the combination of stored carbon and avoided emissions that really tips the climate scales for timber, and a recent innovation has made wood much more user-friendly.
CLT, or cross-laminated timber, is made by layering conifer planks at 90 degrees to each other in three to seven tiers and then gluing them together producing a kind of chunky plywood. These panels are suitable for walls, floors, roofs, even lift shafts. and their strength-to-weight ratio is often better than concrete.
CLT can be used in schools, offices and warehouses and now there's a race to the sky with 85m 'plyscrapers' recently completed in Austria and Norway. So why are wooden buildings still the exception? Mainstream construction is a risk-averse industry and changing this takes radical action.
One approach is law - the French government has decreed that at least 50% of every new public building must be made of wood. This not only allows those structures to store more carbon but also encourages a generation of builders to learn a timber-friendly skillset. But how safe are wooden buildings, you may ask?
Remembering the Great Fire that gutted the medieval centre of London in 1666? In fact, tests of CLT panels in a blaze have shown they tend to form a charcoal layer that protects the core and when combined with heat-resistant glues and claddings they can match or exceed the fire resilience of conventional buildings. There are other benefits too.
Studies suggest that wooden schools can actually lower the heart rate of pupils. Even looking at a wooden wall can reduce blood pressure. So wood is not only renewable, safe and climate-friendly, it can also make you feel good.
Or to put it another way, using wood is really good.
