Watch the full interview (above). A transcript is provided below, edited lightly for clarity.
How can cross-laminated secondary timber reduce the embodied carbon of buildings?
“The embodied carbon in the built environment is going to become increasingly critical, and there are lots of ways that you can focus on reducing embodied carbon. The way cross-laminated secondary timber can contribute is, firstly, by capturing carbon. As long as we keep timber in use as a solid material, then it continues to store atmospheric carbon.
“So the longer that we can keep timber in use, and structural use is a really good example of long-term use, the more the built environment acts as a store for carbon
“Second, there's a potential for it to displace the use of more carbon intensive materials. So by getting waste wood back into use as a structural material, there's the potential for it to replace structural steel and concrete, which are two of the biggest producers of embodied carbon. Weighed against that is the impacts of production of cross laminated secondary timber. So there's the whole carbon accounting question.”
The Flemming Bligaard Award is given annually to an early career academic, whose work has made an outstanding contribution to sustainable development. Colin Rose’s current research, which is funded in part by the €65,000 Bligaard award, focuses on the ‘technical core’ of CLST: the engineering properties and performance of secondary wood.
Do you think the building sector, which tends to be conservative, has recognised the potential of CLST?
“I think we're still in the lab phase. So we haven't gone far in exposing ideas to industry. But the fact that Ramboll is willing to award give me the Flemming Bligaard award to progress this research is a good marker of confidence in the idea.”
Since recording the interview, Colin notes there has been progress in exposing ideas to industry. He says more is being done with UK EPSRC Impact Acceleration funding - and there is demand in the UK market for CLT that doesn't have to be shipped a long distance. At the same time, there is growing interest in the circular economy. Colin has since helped establish UK CLT with a view to commercialising the research into cross-laminated timber.
“And there are other research projects I'm following on from our initial scientific paper on cross-laminated secondary timber. As part of the Horizon 2020 CIRCuIT project, Grimshaw [an architecture firm, with engineers Simple Works, ed.] and a developer in London are looking at the idea of making glulam from secondary timber. There's also been some work on this topic in Ireland, Spain and Norway. So it's gaining traction.”
Read also: What do engineers really think of timber buildings?
“The CLT producers themselves, arguably should be looking at this, but their business model is very much focused on new wood from forestry. And the forests are plentiful. They possibly should be considering the longer-term challenges that will come about from increasing competition for the use of land as global population rises. We get materials like wood from land, but we also need to increasingly grow food.