Green Building with Steel JoistsSteel joists, considered as a part of structural steel, are recycled at a rate of 96 percent - significantly lowering energy use and the nation's demand for virgin raw material.
Choosing steel joists is an environmentally-correct decision, and it qualifies for LEED credits for "green" building design.
Steel Joists: The Choice For Green Building And Sustainable DesignSteel is the most recycled material in North America, according to the Steel Recycling Institute. More than 68 million tons are recycled each year. In fact, all new steel made in North America contains recycled steel.
For architects and engineers working to achieve sustainable design, a building created with steel joists and other steel structural components significantly boosts the amount of recycled products used in the project - a plus when working to achieve LEED® (Leadership in Energy and Environmental Design) credits. The LEED certification program was developed and is administrated by the U.S. Green Building Council, a national non-profit organization, created to encourage design and construction that enhances energy and water efficiency, conserves material and resources and enhances environmental quality and lessens environmental impact.
In addition to its "green" nature, design flexibility is also an advantage to steel joist construction. Based on the span of building bays, steel joists allow for maximum headroom. They also offer flexibility to allow pipes and ducts to run through joist open webs, a procedure not possible with other types of construction. Design flexibility of long spans is also possible with steel joists. Spans of more than 100 feet are not uncommon. In concrete construction, the greater number of support columns needed often limits the designer’s ability to move walls and partitions when buildings are remodeled. This is an important factor in new construction as well as remodeling or adaptive reuse.
Another factor enhancing the sustainability of steel joists is the high strength-to-weight ratio (typically 25 to 1), allowing steel joists to support greater loads. Steel can also perform in both tension and compression, unlike concrete which must be steel-reinforced to resist tensile forces. Steel is also very ductile, making it more forgiving than concrete in earthquakes. And, steel can take uplift and gravity loading because steel has inherent strength in each direction.
Another feature of steel, in general, is durability. When properly protected against rust and corrosion, steel joists and other steel structural members can last indefinitely making them ideal in adaptive reuse projects. Because steel joists have such a high recycled content they already qualify for more LEED certification credits, but using existing joists in adaptive reuse of an existing structure increases LEED credits even more.
The Steel Joist Institute offers a valuable tool to structural engineers, designers and architects for determining load-carrying capabilities of steel joists in buildings requiring renovation or reconstruction. A proposed 80 Year electronic history will be available in 2009 that includes a complete listing of live and dead load tables throughout the 75-year period since 1928. It offers step-by-step investigative procedures and time saving data for use when analyzing existing structures as well as building site information and equipment needed.
This manual includes a complete chronological history of all Institute specification and load tables. A new section features examples for calculating moment of inertia of older joists. This guide is considered by the industry as the best and clearest guide for investigative purposes.
When it comes to creating "green buildings," either with new or reused steel joists (in adaptive reuse projects), choosing steel joists is an environmentally-correct decision, and it qualifies for LEED credits.
To learn more about the U.S. Green Building Council and LEED program, visit www.usgbc.org.
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