Wood: the Good, the Bad, and the “Neutral”

 Bioreviewable

Wood: the Good, the Bad, and the “Neutral”

Cory Dahlstrom,

11/11/20

Time sure has a way of moving quickly, eh? Already it’s November--oh, and already we’ve arrived at the third installment of Bioreviewable! Today I’ll be discussing none other than wood; it’s so commonplace in the world that we don’t think about it too much. What’s the deal with that, you ask? I shall attempt to answer that as I discuss the benefits and drawbacks of wood as a product.

Let’s begin where the wood begins: trees. Like everything else, trees have a life cycle; and depending on the tree, we might harvest its lumber for production purposes. In this case, we like to employ forest management. If you recall, I briefly touched upon this in the previous post! To quote myself, “forests are utilized for lumber and are managed over extended periods of time. The yields from these forests are manufactured in bioproducts. Your furniture may very well be a bioproduct! Wood is a biorenewable resource, managed by us; forests are the first major source of biorenewable resources.” Ah, well said past-Cory.

The following diagram on the left from Puettmann 2012 gives a nice breakdown of wood production:

So, forest management is really the first step in an overarching process of turning a tree into a table or another product. 

On the far left, energy is mentioned--this brings me to some of the “bad” associated with wood products...

Global warming?! Eh? Cory’s going on about global warming again? How can this be?

It always boils down to carbon emissions; that infamous CO2 which is like an invasive species to our atmosphere. We can understand this more by considering carbon neutrality, which is the natural principle that carbon captured by trees/wood is inevitably released back into the atmosphere. But, depending on what we do with trees, the rate at which carbon is “returned” can vary greatly. For instance, wood harvested for lumber temporarily “sequesters” (stores) carbon for up to 200 years, whereas wood harvested for energy (like a fire) will instantly give that trapped carbon back to the atmosphere--which isn’t good! This amounts to saying that even though wood-based construction has a great many benefits, it’s little more than a band-aid fix for the looming problem of carbon emissions. 

Essentially, despite the fact that comparisons between wood and steel or concrete construction will strongly favor wood, there is still potential for global warming in laminated timber. Moreover, even with construction, the total process (“cradle to grave”) from harvesting the wood all the way to producing and delivering products requires energy, which in itself is a source of carbon emissions. The following figure from a Robertson et al study elucidates precisely what I mean:

Indeed, the timber potential is generally lower than that of concrete, however there is still potential nevertheless.

Now, this post has probably sounded a bit more negative than I intended; fret not! Wood’s benefits are numerous and of course have many applications! A very prevalent example (though perhaps a little less in 2020) is paper; another is woodbuilding. Woodbuilding makes use of “engineered wood” (natural wood whose properties become specialized, so to speak); and this engineered wood gives greater variety (and in turn, value) to its industry. 

In a Vox article, The hottest new thing in sustainable building is, uh, wood, one of the buildings included is the Brock Commons, the tallest mass timber building in the world! Here’s a picture taken from Archdaily:

This building is a remarkable achievement! It’s 18 storeys tall, and houses 400+ students. There were about 29 CLT panels installed per floor for 16 floors, thus a total of 464 panels

Anyway, I should emphasize: carbon neutrality is actually a bit more than neutral when you compare wood to alternative materials we could be using! (See the Robertson figure above.)

In conclusion to all of this: wood is a great resource, but its carbon-sequestering capability isn’t the perfect solution to our carbon problems. In fact, some aspects of wood production actually yield carbon emissions themselves. However, wood production still yields comparatively less CO2 emissions than other materials. So, depending on how we view wood, it’s either good because of its vast applications and building potential; it’s bad because it can mean more carbon emissions; or it’s “neutral” because it temporarily sequesters carbon emissions and at the same time yields less emissions than other materials. Me personally? I think the good outweighs the bad; sure, it’s not perfect, but I have faith that we humans will get more creative in order to solve our problems, sort of like way back in my first post when I mentioned we won’t ever “run out” of resources due to our creative thinking. Cheers!

Works Cited: 

Hasan, Z. (2017, September 18). Inside Vancouver's Brock Commons, the World's Tallest Mass Timber Building. Retrieved November 09, 2020, from https://www.archdaily.com/879625/inside-vancouvers-brock-commons-the-worlds-tallest-timber-structured-building

Roberts, D. (2020, January 15). The hottest new thing in sustainable building is, uh, wood. Retrieved November 09, 2020, from https://www.vox.com/energy-and-environment/2020/1/15/21058051/climate-change-building-materials-mass-timber-cross-laminated-clt

Robertson, Adam (2012, July 17). A Comparative Cradle-to-Gate Life Cycle Assessment of Mid-Rise Office Building Construction Alternatives: Laminated Timber or Reinforced Concrete. Retrieved November 9, 2020, from https://canvas.umn.edu/courses/192925/files/14351109/download?wrap=1

Puettmann, Maureen; Bergman, Richard; Oneil Elaine (2013, April). Cradle to Gate Life Cycle Assessment of Softwood Lumber Production from the Northeast-North Central. Retrieved November 09, 2020, from https://www.fpl.fs.fed.us/documnts/pdf2013/fpl_2013_puettmann001.pdf