Timber!

Paul Brannen's book has made me rethink the way I look at wood.

Paul Brannen, former member of the European Parliament and Director of Public Affairs for the European woodworking and sawmill industries, has written Timber! How wood can save the world from climate breakdown. I received an early proof and blurbed for the cover:

“Paul Brannen's engaging and accessible book explains how building materials that are grown instead of mined can change buildings from being a climate problem to part of the solution.”

These were hard words to write, because for a long time I have believed that the virtues of mass timber have been oversold and that we should be using as little of it as possible, as efficiently as possible. Brannen believes that with wood, the more the merrier.

Wood Solultions Fair, 2017 From right: Steven Street, Tad Putyra, Sandara Frank

As background, I have been troubled by some of the pitches for wood since I attended a Wood Solutions Fair in Toronto in 2017 where where Sandra Frank, Marketing Director of Folkhem, a Swedish home builder, showed a low rise apartment building built of Cross Laminated Timber (CLT), noting the wood in her company's Strandparken project was replaced by new growth in 44 seconds.

She was followed by Tad Putyra, President & COO of Great Gulf Homes, Low-Rise Division, who described how his company built houses and low rise apartments out of wood frame using sophisticated Swedish tools. Two different concepts for wood construction, but wood frame uses a fifth as much wood as CLT.

I got frustrated and asked Sandra Frank how, given the pressures on our resources, do we not have an obligation to choose the system that uses the least amount of material, even if it is renewable? She answered the question by saying, "If we use more wood, we are then growing more trees and absorbing more CO2."

I was not convinced. I concluded by noting:

“I believe that everything that can be built out of wood should be, but am beginning to think that you can have too much of a wood thing. I am really coming to wonder if CLT has not become too fashionable, when there are other, simpler wood solutions that use less material, save more forest, and build more homes.”

I am still not entirely convinced. Take Mjøstårnet, the timber tower that is on the back cover of Brannen’s book. It is in a small town that doesn’t need an 18 storey tower. But they wanted to have the world’s tallest timber tower, which it was for about 18 minutes. Wood is light and the building is slender and wants to blow in the breeze, so that had to anchor it with piles 50 metres deep and load up the upper floors with concrete to add mass, it’s ridiculous. I concluded, “It may be treesonous of me to say this, but we should stop this silly competition to be tallest.” Had I seen the cover with this silly building before I read the book, I might have gotten off on the wrong foot.

But I feel it necessary to preface my review with all this because Brannen has changed the way I look at wood. He explains “how timber can decarbonize the built environment,” noting that “For every dry tonne of manufactured timber around 1.8 tonnes of CO2 is removed from the atmosphere. Chopping the tree down does not release the carbon, it remains stored in the wood.” I might have argued that the CO2 was already removed from the atmosphere and was nicely sequestered in the standing tree before it was chopped and which was still removing carbon, but Brannen notes that an aging tree absorbs less carbon, so you want to chop it down at its peak and replant.

“If we build with the wood, we safely store the carbon in the built environment – potentially for hundreds of years. This is a good thing to do. At the same time, back in the forest, we replant the felled trees with new saplings – often three saplings per felled tree – to ensure the process is circular and hence sustainable.”

Again, there are those who will argue about how much is left on the ground to rot, what happens to the roots, what about the kiln-drying and transportation. But we will ignore that because Brannen’s story gets better, especially when one looks at the alternatives.

“Timber’s ability safely to store carbon in the built environment is therefore a great asset in the battle against climate change but the good wood news does not end there because wood has another valuable attribute, the ability to substitute for other materials that are significantly more carbon intensive. This may seem a statement of the obvious – when we build with timber, we do not use concrete – but it is often missed when carbon emissions are calculated for building work.”

These are what are called “avoided emissions,” which I have often complained about, especially when architects count them and take credit for them. I noted in my book “The Story of Upfront Carbon” that this was like being on a diet and counting the chocolate cake you didn’t eat. I have always thought this encourages the use of more wood than is needed; I have seen architects proudly totalling up how much wood they are using, how much carbon they are storing, how much concrete they avoided.

Brannen, on the other hand, revels in it, calling it “a measure of the substitution effect – a figure as valuable in our endeavours to get to net zero as the storage figure.” He even wants to reward the substitutions, to“monetize wood’s ability to store carbon and generate “gold standard” carbon offsets.”

“Those constructing the larger engineered-timber builds could sell their carbon offsets to help reduce the overall financial cost of the construction. In turn this would help make building with engineered timber more competitively priced against building in concrete and steel, and potentially cheaper if the price of carbon rises high enough.”

I complained to Brannen, “No no no this opens up so many cans of worms, critics will spend their entire review focused on this. Sell credits for building big? Encouraging people to use more wood instead of using it efficiently, as little as possible? This is dangerously wrong in my opinion.”

Brannen was unrepentant. “Yes, there is going to be rows about this (good - it raises the issue). Could it lead to greenwashing etc? Yes, absolutely. The key thing is to establish that stored carbon ‘has a value’ in the same way as ‘nature has a value.’”

Perhaps the biggest revelation in the book was Brannen’s discussion of insulation. He summarizes the issue:

We have three urgent points of action if we are to meet our net zero targets by 2050:

1. We need to increase dramatically the amount of renovated/retrofitted homes being insulated. A high standard of insulation in our entire built environment is the single most effective way of driving down energy consumption and fossil fuel usage.

2. At the same time, we need to avoid using those insulations with the highest levels of embodied carbon. And

3. We need to prioritize using those nature-based insulation products that have the ability to store the most carbon, such as wood fibre insulation.

Most insulations have high embodied carbon; in North America, cellulose made from old newspaper is a popular low-carbon alternative, but newspapers are disappearing; I am probably a member of the last generation to actually subscribe to paper editions.

But there is also wood fibre insulation, as made by Steico in Europe and recently introduced to North America by TimberHP in Maine, which processes trees that used to go to the pulp and paper industries. Brannen suggests a better source of fibre: growing plants specifically for the job. He suggests willow:

“Willow is the standout candidate if you want to grow woody biomass quickly in a farm setting. You sink a 30 cm long cutting into the soil with three centimetres showing above the surface and then – apart from holding back the weeds and pests for the first six months – you do not need to do much else. Three years later you have a bushy tree around five metres high with a central trunk that has a girth equivalent to a 20-year-old Sitka spruce grown in a forest.”

Imagine massive plantings of willow and storing all of that carbon in insulation. Throw in some of those monetized carbon credits to make it more affordable. Now we might make a serious dent in insulating our housing, without the burp or vomit of upfront carbon that comes with conventional insulations.

Finally, there is a paragraph that had me banging my head on the table, having written an entire book about why we shouldn’t use the term “embodied carbon.”

“We need to be careful here with the terminology as it can get rather confusing. Wood advocates and climate specialists talk about “embodied carbon” in relation to building materials, a term which sounds similar to “stored carbon” or very similar to “embedded carbon”. However, the first needs to be reduced as much as possible, the second increased as much as possible and the third term is probably not being accurately used.”

Why didn’t I think of that? Such a great explanation of how carbon actually is embodied in timber, and how confusing the language is.

When I visited Waugh Thisleton’s Black and White building last year, I was shocked at how slender the columns and beams were, looking not much bigger than steel would be after it is enclosed in drywall. Andrew Waugh, knowing my preoccupations, noted proudly that they now use 40% less wood fibre per square meter than when they started working with CLT.

Would I feel the same way today after reading Brannen’s book? Yes, I still think that wherever possible, we should use less stuff. I still think we shouldn’t encourage people to use more stuff with things like carbon credits.

But in the end, Paul Brannen has written a sunny, optimistic and positive- relentlessly positive- look at timber. I have some reservations and concerns, but this is a book we needed, that anyone can understand, and will change the way many people look at wood.