Does Steel Construction Have A Lower Carbon Footprint Than Wood?


You want fancy graphs? We've got fancy graphs. Carbon emission reduction by displacing non-wood products, credit Corrim.

Climate Progress asks Which Emits the Most CO2 in Home Construction: Steel, Concrete or Timber? and concludes that building a house with wood has CO2 footprint that is 4.44 times as high as a steel framed house. But I think there are problems with this.

graph carbon stored in wood products

From Wood Construction Goes Seriously Vertical. But Does it Really Sequester Carbon?

First of all, it ignores recent research. They show the graph above from a study of an Oregon clearcut and repeat the information from a 1993 study that claims that harvested wood products sequester only 15% of site emissions as an excuse to completely ignore and discount the fact that wood sequesters carbon. Except that wood does sequester carbon, a lot of it. But as far as this article is concerned, it doesn't happen. Kyoto said so! (except in Kyoto they were not talking about construction,they were talking about carbon offsets.) They are only measuring the energy it takes to run an American clearcut operation and marking it up. Then they have the gall to say:

Emissions caused by logging are measured on site and are not controversial among scientists, but, due to timber industry PR, the public is not aware of them.

I'm sorry, industry PR is hiding data on emissions? They have better PR than the steel industry? I don't think so.


All carbon pools: forest, product, emissions, displacement and substitution/

Oh, and they take the weight of steel from engineers as a given, but for wood they add 15% for lumber yard and site cull, as if there has never been a piece of steel tossed into a bin on a job site, and another 25% for mill waste. Except there is no such thing as mill waste any more, that is where you get the OSB board and the Parallam and the other engineered wood products from. In fact, as Professor Bruce Lippke of the University of Washington notes,

Every time you see a wood building, it's a storehouse of carbon from the forest. When you see steel or concrete, you're seeing the emissions of carbon dioxide that had to go into the atmosphere for those structures to go up."

The authors of the Climate Progress post conclude:

The American housing industry has an historic opportunity to make substantial contributions toward reducing CO2 emissions into the atmosphere. In a rational world, the outcome would be to switch to inert materials for structural components.

Right. In a rational world, the industry would switch from a renewable resource to a non-renewable one made from iron ore and coal. I don't think so.

The headline and content of this post has been revised after correspondence with the editor of Climate Progress.
More on wood construction:
Timber Houses Lead a Double Life. As Carbon Sinks.
Wood Construction Goes Seriously Vertical. But Does it Really Sequester Carbon?
More Proof That Wood Is The Greenest Building Material
Time To Grow, Cut and Use More Wood

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