Assessing Green Building Materials

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.

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.

But in the rush to jump on the green bandwagon, not much time gets spent considering what it means to create a more sustainable building. Some think a label declaring a material to be “green” is all that is required—but figuring out how to make a measurable difference in our environmental impact takes a bit more effort.

The Tools to Do It Right

With almost everyone selling some version of green, it is up to each homeowner and builder to do the research to make better choices. That research must go beyond the product sales sheet to examine how the product is made. Here are some common-sense factors to apply to decisions.

Petroleum

Products made from petrochemicals have a large ecological footprint. Regardless of any “green” marketing, crude oil is responsible for vast amounts of ecological damage—and all petrochemical products bear a share of that harm. And most petrochemical products will persist in the environment long after their useful life as building materials.

Example: Foam insulation carries a dire environmental footprint in its manufacturing, and in its use and eventual disposal.

Heat

Products manufactured using high quantities of heat have large environmental impacts. They consume a lot of fuel and create a lot of pollution in the process. The greater the amount of heat required, the greater the impacts.

Example: Portland cement requires heating limestone to 1,100°F in the calcining process, and then to 2,640°F to sinter the material.

Manufacturing

The more complex the manufacturing process, the more impacts the product is likely to have. Natural materials, such as straw bales, which require little or no modification prior to use, are likely to have fewer impacts.

Example: Cereal straw is cut in the field during the harvesting process and compressed in a simple mechanical baler.

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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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