Green Building Elements

Use of local materials can be a good way to help make a construction project greener. If the materials being used don’t need to be transported from great distances, there is less embodied energy in the transportation of the materials, and thereby the production of those materials has less environmental impact. Of course, there are trade-offs, as this is only one factor in the overall evaluation. Does it make more sense to use a locally produced material if the manufacture has a high level of embodied energy, or would it be better to use a lower embodied energy material that comes from farther away and has higher transportation costs (both financially and environmentally)?

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In the LEED system, regional materials are defined as being “extracted, harvested or recovered, as well as manufactured, within 500 miles of the project site.” That’s a pretty generous radius to work from in many cases. For me, in southeast Michigan, that includes all of Indiana, Ohio and West Virginia, and nearly all of Illinois, Wisconsin and Pennsylvania, and Michigan itself (the western part of the upper peninsula falls outside that radius). However, LEED also sets the mark at just 10% (by cost) of the materials to earn the point (and awards a second point if it reaches 20%). This measure also excludes plumbing and electrical, and specialized equipment, since many of those things come from more limited sources.

Local materials should be explored as an option both because they require less energy for transportation, but also because they are likely to be used in a way that is appropriate for the site and the particular needs of the region. The US EPA map identifies fifteen different bioregions in North America (and subdivides those, when you look for finer detail, down to 182). If you build with local materials, you are also more likely to be building in a vernacular style, and that means building appropriately for the climate of your particular location.

Regional vernacular design can be a useful model to show appropriate design practices for a region. The materials that were used on buildings in the area 100 years ago will give you a good sense of what the regional materials are. And even if you don’t want to build with adobe in the southwest US, the fundamental lesson of large thermal mass walls with limited openings to control sunlight and heat gain can be followed and extended to other materials. Both the materials and the methods of construction should pay attention to local choices.

Image source: US EPA

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