Are Green Building Standards Really Leading to Green?
By Jim L. Bowyer, Ph.D.
People make environmental decisions every day. Paper or plastic? Cloth diapers or disposable? Paper towels or electric hand dryer?
We generally make these decisions based on very little information. Often we simply trust intuitive beliefs.
Weren't plastic grocery bags introduced as an environmental alternative to paper? Now plastic grocery bags are outlawed in some California communities.
Disposable diapers contain recycled fibers, but they make up a considerable portion of our landfills. Cloth diaper cleaning services, on the other hand, use more energy overall, more water, 4 to 5 times more waterborne waste, and more phosphates.
The electricity used to heat the air fans blow on to damp hands is generally generated by burning fossil fuels, which increases greenhouse gas emissions and contributes to global warming. Paper towels, on the other hand, consume about one-half the fossil energy, are made from a renewable resource, and once used, can be burned to generate clean energy.
How certain can we be of the true environmental impacts of our choices? There are, after all, complicated and complex systems at work.
Some builders, architects, governments and consumers have turned to green standards for guidance. Green building standards are supposed to advance environmentally friendly design and construction. The idea is to minimize our "environmental footprint" by embracing certain building practices, including the use of environmentally preferable building materials.
But these standards are only "green" to the extent that the practices, materials, and products they promote are actually environmentally better than practices, materials, and products not specified.
Unfortunately, many of today's green building standards fail this simple test. Provisions of several popular green building programs are developed through processes that are more political than scientific, and driven more by intuition than by data and analysis.
Intuition has led to programs that today promote steel over wood framing, fiber cement siding over engineered wood composites, OSB over plywood sheathing, almost anything over solid-sawn lumber. Yet, systematic analysis over the life of these products shows no clear environmental advantage of favored over non-favored products, with some favored products clearly environmentally inferior.
For instance, while the leading green building program often favors recycled-content steel over wood for framing interior walls, environmental life cycle assessment shows that using steel-framed walls requires twice as much energy and releases of 3 to 41 times more emissions to the air of carbon dioxide, cyanide, phenolics, and methane.
For exterior walls the differences are substantially greater. If from this point forward every new home built in the United States that would normally be framed in wood were instead framed in steel, the difference in energy consumption would be roughly equivalent to continuously operating a fleet of 950,000 SUVs, each driving 20,000 miles each year.
So how can it be that well-known green building programs, in business for the stated purpose of improving environmental performance, promote the use of steel over wood? The answer lies in the fact that the harvesting of trees is politically incorrect in some circles, and that only one of the 29 green building programs in operation nationally bases building design and materials selection on environmental life cycle analysis (LCA).
Life cycle assessment offers a broader perspective on green building than prescriptive standards and provides a comprehensive decision support matrix. LCA is a scientific methodology that considers each building material from cradle to the grave and makes clear the tradeoffs between one design or one material and another.
It is important that green building standards in fact lead toward lower environmental impact. It is likewise important that the nation's green building programs move as rapidly as possible to incorporate the use of the best available tools, including life cycle analysis, in identifying environmentally preferable practices and building materials.
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Jim Bowyer, Ph.D. is a Professor Emeritus from the Department of BioProducts and BioProcess Engineering at the University of Minnesota. He is also Director of the Responsible Materials Program, Dovetail Partners Inc., White Bear Lake, Minn.