Green Products: Trends & Innovations

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Recycling is the Heart of Steel

The U.S. Steel industry underwent a transformation in the 1970s, and, today, steel manufacture takes less energy and is done with one-tenth the manpower it took 30 years ago.

In 2003, almost 69 million tons of steel were recycled in the U.S. or were exported for recycling. About 88 percent of all steel products, and nearly 100 percent of steel used in beams and plates in construction, are recycled into new steel products at the end of their useful life.


Courtesy AISC

"We have achieved a very efficient production process and a very high level of recycled content," says Christopher Hewitt, a LEED-accredited staff engineer with the Engineering and Research Dept. of the Chicago-based American Institute of Steel Construction, Inc. "What we are saying today," Hewitt says, "is that steel is a good choice for sustainable projects."

An emerging method of analyzing the environmental efficiency of materials is the use of embedded energy approaches, sometimes referred to as life-cycle analysis (LCA). The method involves calculating the total amount of energy associated with the production, manufacture, transportation and construction of materials, their components and by-products.

Unfortunately, LCA is still in its infancy, and comparisons are difficult, not only in structural components, but in almost every aspect of construction. No credible study has yet been done, for instance, comparing the embodied energy of structural wood products to steel or concrete in the U.S. construction market, Hewitt says.

LEED, he says, is moving slowly in the direction of life-cycle analyses that would award credits for durability and longevity, but it is unlikely that that meaningful data from such studies will be available soon. LEED, however "provides a snapshot of what is going on in the manufacture of building materials," Hewitt says, "and its emphasis on recycling and reuse means that framing with steel can earn owners ‘green' credits."

The electric arc furnace (EAF) process, the primary method in the manufacture of structural beams, steel plate and reinforcing steel, now uses 95-to-100 percent recycled steel. "Recycling is second-nature for the steel industry," Hewitt says.

Because it is produced to exact specifications, on-site waste is negligible. Material from construction and demolition is easily recycled, and, because it is dimensionally stable, steel creates a tight building envelope, leading to better HVAC performance over time.

"To enhance LEED ratings," Hewitt says, "it will be important to know the percentage of recycled steel that is ‘post-industrial' and the percentage that is ‘post-consumer.'"

That will require data from the mill where the material is obtained. To access that information, Hewitt urges users to contact the mill directly or to visit the AISC website for recycled-content templates from member mills.

For a more thorough understanding of the recycled content of steel, Steel Recycling Institute (SRI).

 

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Originally published in Architectural Record.
Originally published in February 2005

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