'Green' can be an illusion in construction
Building certification programs don't necessarily see the forest for the trees.
Just 10 years ago, any reference to "green" in the construction industry would have translated to cash flow or the color of countertops. Today, that word is widely understood to refer to practices and products aimed at minimizing energy consumption and overall environmental impacts linked to constructing and operating buildings. Such practices and products are outlined in a number of green building programs, including LEED (Leadership in Energy and Environmental Design) and Minnesota Green Star.
There is no downside to creating energy-efficient, low-impact buildings. Environmentally better buildings benefit everyone. But it is important that green standards actually lead to environmentally better structures within our communities. Unfortunately, this is often not the case.
One problem area is the designation of environmentally preferable materials. In both the LEED and Green Star programs, designations of environmental preferability are not based on careful analysis but rather simply on intuition. Designations based on single attributes are also common.
The focus on intuition and a single product characteristic keeps things simple and easy to comprehend -- simple for consumers and simple for organizations making judgments about various products: A product contains recycled content (good) or it doesn't (bad); it is "natural" (good) or it isn't (bad); it was produced from rapidly renewable resources (good) or it wasn't (bad).
Unfortunately, focusing narrowly on product attributes is useful in identifying environmentally preferable products only in the most straightforward situations. Life-cycle analysis (LCA) -- a systematic analysis that takes into account the entire impact of a product or material from raw material extraction through the life of a building -- can show that the simple approach is often wrong. For example, LCA comparison of several common wall-framing materials -- only one of which contains recycled content -- shows the material containing recycled content to have by far the greatest negative environmental impact in terms of energy consumption, water use and total emissions, including greenhouse gas emissions, from cradle to grave. And yet, green programs routinely encourage the high-environmental-impact option solely based on the attribute of recycled content.
Another problem relates to a near-universal requirement in green building programs that "green" credits only be awarded when it can be demonstrated that any wood used has been responsibly produced. Curiously, there is no similar requirement for any other material -- steel, concrete, plastic -- despite well-known impacts associated with each. The inescapable conclusion is that high-environmental-impact, high-social-cost products are routinely finding their way into buildings certified as "green."
Perhaps the worst characteristic of most green building programs today is defined by what is not considered in identification of environmentally preferable materials. At the moment, most programs -- including LEED and Minnesota Green Star -- don't consider the total energy consumption required to produce products and product assemblies, even though energy used for this purpose is often equivalent to many years of energy consumption associated with a structure. Also not considered are emissions to air and water, including emissions of greenhouse gases.
Fundamental change in the way that green building programs assess construction materials is needed. Rather than relying on intuition, systematic analysis of the total environmental impact of a product or process should be incorporated into all green building programs. Ironically, current practices are encouraging unsound environmental decisions at a time when precisely the opposite is needed.
Jim Bowyer is director of the Responsible Materials Program at Dovetail Partners Inc. and is professor emeritus in the Department of Bioproducts and Biosystems Engineering at the University of Minnesota. Tom Milton is a technical director for WoodWorks, an organization that educates and provides resources for those building with wood in nonresidential structures.
