continued

Concrete, for example, has a fairly high amount of "embodied" energy. This is the total energy that is spent in production and placement. Standard cement must be extracted from its mineral state, cooked in a furnace, pulverized, bagged, and shipped. Aggregate for concrete is mechanically crushed, and the sand must be mechanically extracted and transported.

These ingredients for concrete are mixed with water (often treated for potability) driven to a site, often placed mechanically, and usually reinforced with steel (which has its own embodied-energy story). In the curing process, concrete gives off a substantial amount of greenhouse gases.

For decades after construction, concrete does its job admirably with little additional impact on the environment until demolition, when removal usually entails additional energy in crushing and transporting it for reuse or disposal. However, by specifying alternative admixtures and components and their sources, some of these environmental costs can be minimized.

"The most practical, if still somewhat generic way for a designer to compare the life-cycle-wide environmental impact of construction materials is to use the software BEES (Building for Environmental and Economic Sustainability) from the National Institute for Science and Technology," says Peter Reppe, a mechanical engineer for Solarc Architecture and Engineering. "Everything else involves working with specific manufacturers or using specialized, expensive software tools and life cycle analysis (LCA) consultants."

BEES can be downloaded free and is available only for Windows operating systems. Some 200 building products are analyzed using internationally recognized science-based standards.

However, methods for accurately determining life cycle impact of materials are still being fine-tuned and there are questions concerning the accuracy of current methods of analysis. While U.S. practice lags behind that of the Europeans in this area, BEES continues to improve as a useful tool for basic information.

One easy way architects can reduce embodied energy is to specify local materials. Besides the design benefits of reinforcing a building's relationship to place and contributing to the local economy, this practice can substantially reduce transportation energy and costs.

The Greening of Government

BEES was developed in part to support the Environmental Protection Agency (EPA) Environmentally Preferable Purchasing (EPP) program — one of the elements in the "greening of government" initiatives set in motion by the Clinton administration.

The U.S. government is now the largest consumer in a country that uses 25 percent of the world's resources but represents only 5 percent of its population. In 1998 President Bill Clinton signed an executive order requiring federal procurement officials to purchase "products or services that have a lesser or reduced effect on human health and the environment when compared with competing products or services that serve the same purpose." A request for proposals (RFP) for a government project will likely require materials that adhere to EPP program guidelines.

The EPP program evaluates products based on their environmental and functional performance. The program's Web site includes interactive tools, case studies, standards, and methods for identifying preferred products, and a database of green labeling initiatives.

The EPA and the U.S. Department of Energy have also developed a number of other consumer programs including the Energy Star™ program, which applies labels to a wide range of appliances, building products, and in some cases buildings, according to their energy performance.

Beyond Cradle to Grave

Visionary architect William McDonough and chemist Michael Braungart teamed up to form McDonough Braungart Design Chemistry (MBDC) which promotes a certification program called Cradle to Cradle (C2C).

The first level involves a material's basic capacity to be recycled. A "technical nutrient" has the ability to be recycled indefinitely in industry. A "biological nutrient" must be able to be totally reabsorbed into nature.

According to the overall environmental and social impact, materials can receive silver, gold, or platinum certification. The intention of MBDC is to integrate cradle-to-cradle certification into the EPP program.

LEED-Certified Materials

For building projects seeking LEED certification, green materials can earn points. The LEED program doesn't yet award points related to EPP or most other certification programs, though there is some movement in that direction. However, LEED does credit attributes such as recycled content in materials and the use of certified sustainably harvested wood products. It also recognizes "rapidly renewable materials" such as bamboo that can be planted and harvested within a ten-year cycle.

A useful resource that can help sort through the maze of green materials is GreenSpec — similar in concept to Sweet's Catalog. Available both online and on paper, it makes information available in several forms including standard Construction Specification Institute format. Product listings include information on potential LEED points and basic information about what makes them green. Also available on the GreenSpec Web site are current articles on green materials and clearly formatted case studies showing an array of sustainable strategies.

In construction documents, architects should be specific about LEED-related products and cautious about any substitutions that might compromise later LEED certification. All compliance requirements should be included in the Supplemental Conditions section of the specifications.

Natural Building Materials

Perhaps a bit outside the mainstream of architectural practice is the natural building movement, which focuses on biobased materials such as straw bale and rammed earth. As the technology becomes refined and as local building codes become more open to alternative methods, several of these materials may be moving into the mainstream. Recently, the large architecture firm HOK used straw bale in their design for the Santa Clarita Transit center in California.

There is much work to be done to clarify standards, labeling, and certification for green materials. But even as this field gradually achieves greater public awareness, architects have the opportunity and responsibility to use the available tools to help educate clients and builders while making their buildings less of a burden on the environment.

Discuss this article in the Architecture Forum...

Michael Cockram is an adjunct assistant professor of architecture at the University of Oregon. He is the director of the Italy Field School Program.

SUBSCRIPTION SAMPLE Composite plastic/ wood products use reclaimed wood and plastic to make a durable exterior decking material. Photo: Michael Cockram (top) and Trex (bottom) The new Clinton Presidential Library has durable bamboo flooring. Laid in strips, it is comparable to wood flooring. Photo: Michael Cockram A composite board made from reclaimed plastic and sunflower husks has an intriguing pattern. Photo: Rudy Berg Recycled glass is molded into a variety of tiles by the Aurora Glass Foundry, a nonprofit company formed to support affordable housing projects. Photo: Rudy Berg Cotton insulation uses denim and other reclaimed cotton fibers in a batt that gets R-values comparable to those of fiberglass. Photo: Rudy Berg Made from 100 percent Tetra Pak juice containers, Tectan board is colorful and dense and can be nailed and screwed. The reflective foil gives the surface a shiny playful quality. Photo: Rudy Berg   Click on thumbnail images to view full-size pictures.