3 – Wood for Good
“We got ourselves into this climate mess with aviation, deforestation – even too much procreation”
The punchy slogan to Tom Heap’s new BBC Radio 4 podcast, 39 Ways to Save the Planet, a bubbly and optimistic take on the climate emergency we face ahead of us. In episode 3, Wood for Good, Tom explains how timber, and in particular, CLT (cross-laminated timber) can be used and harnessed as a technology used to reduce carbon emissions.
The podcast gets going as you arrive in a room with the sound of saws cutting through planks of CLT in your vicinity. Tom describes the smell and aroma of sawdust and sap, the combination of which you can nearly smell yourself. Michael Ramage, a Reader of Architecture and Engineering at Cambridge University, describes the anatomy of a typical CLT beam whilst dissecting it with a chainsaw. He then explains his passion for the new material by describing how it is the newest construction material in the market and its importance to the environment in the future. Michael then proceeds to demonstrate the surprising strength of CLT beams by distributing a significant weight on it using a hydraulic press. The slender beam eventually breaks, but could withstand 2 metric tonnes of force upon it, a weight comparable to that of a large car. After showing the impressive strength of CLT planks, Tom then explores the wider reach of using timber as an anti-carbon tool by delivering some absorbing facts about the environmental capacity of timber.
Timber is a sustainable and renewable material. Whilst the idea of cutting down trees to use for buildings seems like it would cause widespread deforestation, a closer look into the management of timber production reveals quite the opposite. The timber that is used in construction across Europe is sourced from purpose grown trees in managed woodlands. Using these sources, the time it takes to grow enough timber for the material to house a family of four is 7 seconds. A 300m tall skyscraper takes just 4 hours and Canada has the timber resources available to sustainably house 1 billion people. Whilst the supply of timber seems readily available already, the renewability of the material is a key feature. Three or four trees are replanted for every one cut down in well managed timber production woodlands. This actually provides an opportunity for large scale reforestation and would evolve the fight against climate change further.
However, the main selling point of using timber in construction is carbon capture. As a tree grows it sequesters carbon in the air and turns it into oxygen. Even when the tree is cut down, the carbon stored within remains in the timber. So effectively, Greensted Church in Essex, the oldest timber church in the world, has been storing carbon emissions within its oak walls from the 11th Century. That’s nearly an entire millennium of carbon storage. It is therefore key to build with timber long term. If timber was used to build our housing, schools and even more of our infrastructure in the future it really would just be a question of how much carbon we can store. We need to plan for buildings that will last not just the next 20 or 30 years, but the next few hundred and beyond.
If you enjoyed learning about timber in construction head to https://www.bbc.co.uk/sounds/play/m000qy43 to listen to the full podcast of Wood for Good, as well as the rest of Tom Heap’s series of 39 Ways to Save the Planet.