US Hardwoods LCA

By Elizabeth Baldwin

So I’ve done a bunch of posts looking at illegal logging issues in the US—now let’s look at one of the really good things within the industry.

The American Hardwood Export Council (AHEC) is working on the largest ever Life Cycle Assessment (LCA) project to cover hardwood products.

The LCA study looked a project in Australia that utilized about 15m3 of US Walnut lumber.  The analysis included some great results and facts:

  • For walnut, federal figures place the US harvest averages around 1 million m3 each year, well below the annual growth rate of 3.6 million m3.  Therefore even after harvesting, an additional 2.6 million m3 of walnut accumulates in US forests every year.
  • It takes about five minutes for the 15m3 of walnut used to be replaced by new growth in the forest.  (For more information on growth rates, go to their new site:  Grown in Seconds.)
  • The study shows that the walnut kiln-dried lumber used in the project stores the equivalent of 31 tonnes of carbon dioxide.  It will act as a carbon store for as long as it remains in the building, longer if reused or recycled. At the end of the building’s life, if the walnut is not recycled, it could be burnt as a renewable fuel generating up to 37,000 KWh of energy.
  • In LCA terminology, the walnut used in the project has a “Global Warming Potential” of minus 13 tonnes.

The study looked into freight costs in terms of energy.  It is well established that sea freight’s environmental impact is far lower than rail and road.  The study determined that transporting hardwoods over 6000km across the Atlantic requires little more energy than an overland journey of 500km.

Actually, the LCA found that for the factor known as “Global Warming Potential (GWP),” harvesting and milling and transport are have smaller impacts than the kiln drying of the lumber.   But US hardwoods win out there too over many others because so much of the energy is produced by sawmill residue rather than fossil fuels.

The study tells us what we all know.  Wood is Good.  And the US Hardwood industry is starting to get the hard numbers to prove it again.

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