Can Cross-Laminated Timber Save the World?

Anthony Thistleton makes a persuasive case in a new book, 100 Projects UK CLT.

A year ago, after listening to Anthony Thistleton of Waugh Thistleton Architects speak, I wondered what's the best way to build in wood? Should we be using mass timber when alternatives are more efficient in their use of material? Now, Anthony Thistleton answers loud and clear: essentially, yes, and the more, the merrier. He has just published a new book, 100 Projects UK CLT, which shows the phenomenal growth in the use of wood, demonstrated in "100 hundred ground-breaking CLT (Cross-Laminated Timber) projects, demonstrating the UK’s leading position in the use of cutting edge technology to develop buildings from precision engineered timber modules."

Anthony Thistleton/ Photo Lloyd Alter/CC BY 2.0Anthony Thistleton (seen above last year in Toronto) explains:

The more we build using CLT, the more carbon we can store and we create a market for timber that will drive re-forestation. Planting more trees is one of the only realistic ways we have of reducing CO2 levels and it will only happen at scale if it is driven by demand. This is a critical time in the fight against irreversible climate change – the widespread adoption and growth of CLT quite literally has the potential to save the planet.

© Duggan Morris/ Alfriston Pool © Jack Hobhouse

I am always a bit leery of things that promise to save the planet, but in this case, he might be right, particularly when it is used instead of other materials with a positive carbon footprint.

Not only is building out of CLT faster, better and more efficient than traditional methods, it can also play a huge role in tackling climate change. When we use CLT, not only do we create long term storage for the carbon that was absorbed during growth, we also offset the potential emissions from materials such as concrete and steel which have high levels of embodied energy.

© Haworth Tompkins/ Open Air Theatre © Philip Vile

It is true that a cubic meter of wood sequesters a ton of carbon dioxide, and when sustainably harvested and replanted, the growing trees are actively sucking CO2 out of the atmosphere and making it solid, or as author Bruce King calls it, building out of sky. He wrote:

We can structure any architectural style with wood, we can insulate with straw and mushrooms... All of these emerging technologies and more arrive in tandem with the growing understanding that the so-called embodied carbon of building materials matters a great deal more than anyone thought in the fight to halt and reverse climate change. The built environment can switch from being a problem to a solution.

But it is not without its own footprint of transport, of kiln drying (although that is often done with biomass). There are questions about forest management. Can it really save the planet?

© Waugh Thistleton Architects/ Dalston Lane

Dalston Lane by Waugh Thistleton shows the way by demonstrating more than just wood construction. It is literally built on top of a transit line, so it is accessible to low carbon transportation. Its design is informed by the quality of the material; low and broad, because the wood is so light that wind loads become important. It is not just about changing materials, but building the appropriate design in the appropriate place, enabling a zero-carbon lifestyle.

The book also is a great introduction to the benefits that go beyond just storing carbon; it is a healthier and safer build, with as much as an 80 percent reduction in deliveries compared to a concrete structure. It acknowledges concerns about whether it is the most efficient way to build low buildings, noting that under four floors, "a timber frame or SIPS structure may be more appropriate." It addresses the issues of cost, noting that "a CLT structure provides far more than a basic structural frame."

© Feilden Clegg Bradley Studios/ Woodland Trust © Peter Cook

There are some who are not yet convinced that wood will save the planet; read Paula Melton here in Building Green. I have been skeptical in the past, but the authors do a good job of addressing the concerns. Instead, we should celebrate these impressive and sometimes amazing projects, a hundred buildings that apparently store as much carbon as emitted by 12,180 cars or 6,142 houses. Anthony Thistleton says:

"This book showcases the breadth and diversity of buildings and the number of well-known architects, developers and contractors exploring engineered timber. It shows that this material is not a trend but represents a fundamental change in the way we deliver buildings - a construction revolution.”

A revolution indeed. The book is available as a free download at Thinkwood.

© Feilden Clegg Bradley Studios/ The Hive © Hufton+Crow