Less is More Green

03/11/2002 |

Special Report: Turning Green Into Gold - Part 2

Currently, 95 percent of all structural steel in the United States is made from recycled steel. But sustainability goes beyond a product’s recycled content to include the most efficient use of the product or material. A typical post-and-beam steel frame uses eight to 10 pounds of steel per square foot, compared to the staggered-truss that uses 5.5 to 6.5 pounds of steel per square foot. This can reduce the amount of steel needed by one-third to one-half.

There’s a synergy to this design. Fewer columns are needed and less steel is used. Even the precast floor planks weigh up to 30-percent less than poured-in-place concrete methods. This allows a simpler foundation that further reduces the amount of steel and concrete used in the project.

It is also a practical solution for reducing floor heights. The obvious benefit is the opportunity to increase the number of floors within the building envelope. Another is the ability to reduce the ratio of building exterior to building floor area. While a subtle benefit, a building’s exterior skin can cost more than its structural frame. Also reducing a building’s exterior surface area can reduce the heating and cooling load for the mechanical system. Other areas for savings include reductions in plumbing riser heights, and the time and cost of applying fireproofing to the steel.

From a construction management perspective, there are benefits as well. Using prefabricated steel and precast concrete allows the work to be done by a single subcontractor rather than multiple subcontractors. Bidding is usually energetic due to a large pool of qualified subcontractors. Since there are fewer structural elements, this translates into fewer shop drawings, fewer trucks making jobsite deliveries, and faster erection that allows other trades to begin sooner.

Continue Article >> Part 3 - Specification Overkill

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