Assessing Green Building Materials: Page 3 of 5

Beginner

Inside this Article

The notion of building green has become mainstream in recent decades, thanks to the efforts of a small number of builders on the fringe of the building industry.
High-performance doesn’t necessarily equate to “green”—for example, petroleum products, such as foam insulation, have high embodied energy and major impacts on ecosystems.
Concrete has advantageous building and thermal properties, but is high in embodied energy and very high in carbon dioxide emissions.
Lumber is a renewable resource, albeit slow to regenerate. Its embodied energy depends on the distance between origin and use.
Straw bales are an agricultural “waste” product, with low embodied energy and good thermal performance.
Forest products may travel long distances between their material harvest and end use, which drives up their embodied energy.
Often, it’s the final energy performance of the structure that dominates its classification as being “green.” But this is only one aspect of an ecofriendlier building.
Per ton-mile, ships use only 1.3% of the fuel consumed by trucks. However, goods are usually transported over longer distances, resulting in high embodied energy.
Trains use only 0.8% of the fuel used by trucks to move freight; shipping by train significantly reduces a product’s embodied energy due to transportation.
When available, natural building materials, sourced and processed locally, are often the best bet for “green” solutions.

Overall Design

People make the buildings—the materials are only a part. A building is a manifestation of human ingenuity and relationships. It takes the right people to make a building that approaches sustainability, and finding them is equally important to material choices.

Example: Straw-bale walls built poorly by an inexperienced builder can have greater compromised energy efficiency than well-built stud-framed and conventionally insulated walls.

If a product claim sounds too good to be true, it probably is. There is no perfect building material. If a material scores lots of “green” points in one or two areas, it probably has drawbacks in others. Find out both the pluses and minuses before making a decision.

Find trustworthy sources to help your decisions. Third-party certification (especially those overseen by boards that aren’t dominated by industry representatives) is a good way to ascertain a product’s environmental claims.

Beautiful buildings tend to receive care and maintenance, and last a long time. If nobody cares about a building, even if it scores lots of sustainable points for its material selection, it is more likely to have a short lifespan. Create something that future generations will appreciate, and they will shepherd it through time.

Setting Sustainable Goals

Greenwashing—where environmentally harmful products and materials are marketed as being green—is a large barrier to reducing our impact. Without considering the entire life cycle of the elements in our buildings, we cannot know if we are minimizing our impacts.

Homeowners or builders must first establish their environmental goals, and then consider materials that perform well without undermining overall environmental performance. Environmental merit can be judged in three categories:

Low overall energy consumption in the finished building. This may be the most comprehensive way to judge the “greenness” of a material or system. Energy Star, EnerGuide, and a host of energy modeling software programs can be used to compare energy impacts of materials and systems.

Reduced toxics or environmental impacts. Using recycled material, reducing embodied energy, responsibly harvesting and producing, durability, and reducing or eliminating waste are all included in this metric. The Inventory of Carbon & Energy (download at bit.ly/ICEdwnld) is a free database for comparing embodied energy of materials. Free software programs like the Athena Institute’s Life Cycle Assessment (athenasmi.org) can help with understanding environmental impacts over a material’s life span.

Creation of a nontoxic interior environment. Clean air and water; proper humidity and ventilation; access to natural light; comfortable interior temperatures; and reducing or eliminating radon are included. Greenguard (greenguard.org) is a reliable third-party rating system for a product’s impact on indoor air quality; the Pharos Project database (pharosproject.net) has in-depth information on chemicals in building materials.

These three areas constitute a building’s life-cycle analysis. Ideally, for each product, materials research follows the path of all materials and systems—from harvesting raw ingredients to manufacture, transport, and use, to waste and disposal issues.

Comments (4)

Byrdhouse9's picture

The article in the paper magazine includes a table called "Comparing Materials", showing the embodied energy per kilogram for various insulation materials. Is there data available that corrects for the fact that some kinds of insulation provide much more R value per unit weight than others? Light insulation like fiberglass and polyurethane foam would fare much better if the comparison showed energy per unit of R value.

Michael Welch's picture

Energy per R-value would be a great indicator to have.

Byrdhouse9's picture

There is a typo in the "Transportation Impacts" paragraph. The 0.3 gallons of fuel per ton mile for trucks should be 0.03. Typical mid-size trucks achieve this, and heavy trucks often do as well as 0.01 gallons per ton mile. For example, my old F-350 gets a pathetic 10 miles per gallon when hauling 3 tons, but that works out to 0.033 gallons per ton mile .

Allise Burris's picture

Sliding that decimal would mean that ships and trains consume approximately 10% and 30%, respectively, of the fuel required by trucks for the same tonnage. I believe the ~1% and ~3% numbers of the photo captions could be correct.

Also, do pickups and semi-trailers really achieve nearly the same fuel efficiency by weight carried? Or do we define "heavy" trucks differently?

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