Friday, June 29, 2007

Choosing sustainable materials

What exactly is a sustainable building material, and how can you be sure you’re choosing the best one?

A Life Cycle Analysis (LCA) can be used for balancing the environmental and economic performance of building products. LCAs calculate the total embodied energy of a product by considering harvesting, manufacturing, distribution and eventual disposal. There are many LCA resources available, a few of which are included here.

  • Perhaps the most well-known LCA system, the Athena Sustainable Materials Institute is attempting to make their software more accessible to builders. They offer free demo software for their Environmental Impact Estimator available on their website.
  • The BEES (Building for Environmental and Economic Sustainability) software, created by National Institute for Standards and Technology (NIST) Building and Fire Research Laboratory can be downloaded for free from here. It is aimed at designers, builders, and product manufacturers and includes actual environmental and economic performance data of many products.
  • The Boustead Model version 5.0, by Boustead Consulting out of the UK, offers a free demonstration disk from here. The program hosts an extensive database of fuels and energy use, raw materials requirements, solid, liquid and gaseous emissions.
  • ECO-it, created by PRé Consultants from the Netherlands, calculates the environmental load of a product and shows which parts of the product contribute most. A demo version can be downloaded from the website or the full software can be purchased for $147.
  • If LCA software is not available, The U.S. Pollution Control Agency has an Environmentally Preferable Purchasing Guide that explains the “green” attributes of certain materials.
  • If you still have questions about sustainable materials, Dovetail Partners offers detailed reports and information about responsible consumption and sustainable materials.

As an added note, when I choose materials, I prefer to use local materials over anything else. Even if FSC-certified wood is available from China, I prefer to use non-FSC wood from Minnesota. How you choose materials is really up to you.

One thing to keep in mind: a recent study estimated that the wood from a log home could build 12 regular stick-frame homes. However, if this log home was built using logs from the local region, the total embodied energy of that home would be less than from those 12 typical stick-frame houses. The log home construction also increases the demand for large diameter wood, which means people will keep growing it in the forests, and stimulates the local economy. I am not advocating either type of construction over the other, but more the understanding that we need both types of housing in order to stimulate diverse forests, and balance housing needs with embodied energy.

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