Why we must make the most of our timber

The built environment has seen a significant shift towards a future where we work to minimise the impact of the construction industry on the natural world. This move from an “exploitative past of refining materials” to a future where we “cultivate our materials in collaboration with nature” was the focus of the keynote speech from Professor Michael Ramage at the Footprint+ exhibition.

Professor Ramage made his keynote speech at Footprint+’s timber stage, sponsored by Timber Development UK, where he explored the challenges and opportunities that exist around increasing the use of timber in the built environment.

Ramage is Professor of Architecture and Engineering at the University of Cambridge, a department that has a particular interest in the embodied energy of buildings and how we can use natural materials as replacements for conventional materials.

He said: “The goal is to replace concrete buildings around the world with their equivalents or improvements in timber. Timber is already competing directly with steel and concrete [and] I think we’ll see this trend increasing. But, in addition to valuing buildings that are made out of timber, we also have to value the forests they come from, and the value they give us ecologically, socially, environmentally and materially.”

Professor Ramage says one of the ways this can be done is by using timber in ways that give it the longest possible engineered value, and by using the logs efficiently and effectively, rather than seeing them be burned in low-value products.

He explained: “We’ve spent decades thinking about operational carbon and creating buildings with lower energy consumption, and now we now need to move to lower embodied energy materials. And this is a specific problem connected to the built environment.”

Professor Ramage used the example of a four-storey timber student accommodation building in Cambridge, which has an embodied energy equivalent to 1.6 tonnes of CO2. A study showed that the same building in concrete has around 2.5 times less embodied energy than timber, and steel was almost four times less. This is even before we take into account the fact that every kilogram of timber stores 1.8 kilograms of CO2.

He said: “Timber is wildly more efficient than any technologically based carbon capture storage device, and always will always be. Our challenge, and our opportunity, is to increase the financial value of that timber by better establishing its environmental and carbon capture value – and to keep that wood out of the atmosphere for as long as we can.

“If we can track and understand where timber is in our buildings, and when we have multiple lifespan buildings, how that timber goes from Building A to Building B to Building C, we can then see timber as a truly global carbon sink and understand it in the context of how much more efficient it is than industrialised carbon capture and storage.

“In England alone we need something like 300,000 houses a year, which if they were built with timber roofs would account for up to 9 million tonnes of CO2 equivalent every year. And we can do this – it’s not that hard.”

Professor Ramage explained that Cambridge University is currently working with architects Waugh Thistleton on a new model building school, using a very specific kit of parts that include glulam and CLT so that the building can be reused and reassembled. While it has been put together in this case to create a small extension for a school in Cambridge, Professor Ramage believes the model could also be replicated in a much larger school, and in many other of the residential and commercial buildings that are badly needed.

He said: “Most of the buildings we need around the world are probably 15 storeys or less, and that is exactly where engineered products in timber perform best in comparison to steel and concrete. There are a huge number of remarkable timber buildings already in the world today; some hundreds of years old, and some currently under construction. But we still see the need to eliminate the barriers to making timber much more mainstream and the first material that people go to when they think of building.”


More skills and a holistic approach is needed

Professor Ramage also believes that the successful growth of timber usage in construction requires a strong investment in terms of materials, manufacturing, technology and skills.

He said: “One of the things that I want all of us to recognise is that designing, engineering and creating large-scale buildings in timber has very much been led by the UK, and is one of the skills that we need to expand and do more with.  In 1885, the first steel frame skyscraper was built, and in less than 50 years we were able to build the 381-metre high Empire State Building from steel. Now we have a much better understanding of material science, and we can do something similar in timber.

“One of the most interesting things for the future of engineered timber is how we build with it. Timber is so much lighter than the equivalent steel or concrete, which helps us construct large-scale timber modules off site, limited only by the size of the crane needed to move them into place. The Midwest of the United States, for example, is full of extremely large buildings that are now derelict factories and could be repurposed for large-scale off-site timber construction without regard for the harsh winters.”

This large scale off-site timber construction does come with its challenges, however, as Professor Ramage explained.

“One of the issues with volumetric timber construction is that you’re transporting a lot of air, and that’s not necessarily economically viable. Something I see as a tremendous opportunity around the world, and particularly here in the UK, is to invest in the development of high-value timber manufacturing, such as CLT. Manufacturing adds 30-40% to the value to the timber itself, so once we put that value into the timber, we have to handle it much more carefully, so the handling becomes expensive.

“So we need to lead the future timber construction of both the UK and around the world by investing in relatively local factories for high-value capacity manufacturing. The raw material can be supplied and moved to these factories quickly and cheaply, then you do the specialist manufacturing and transport that a relatively short distance, making sure that timber goes to the highest value construction products.”

Professor Ramage concluded: “I suspect something like 80% of buildings under construction in the UK that are under 20-storeys tall could be made in timber. So that’s a challenge for all the developers, architects and engineers out there. If you’ve got a project, pick up your pencil and think ‘how can I do this in timber’ before I think about anything else. You might be surprised.”