Structural Steel: The Premier Green Construction Material
Structural steel is the premier green construction material. Its high recycled content and recycling rate exceed those of any other construction material. Over the past three decades, the steel industry has reduced greenhouse gas and overall emissions by 36% and increased the water recycling rate of steel production to 95%. Today, the American steel industry is the least carbon-intensive of all major steel-producing countries, and its footprint will continue to decrease as the U.S. power grid becomes more and more fossil-free.
Structural steel produced in the United States contains 93% recycled steel scrap, on average. At the end of a building's life, 98% of all structural steel is recycled back into new steel products, with no loss of its physical properties. As such, structural steel isn't just recycled but "multi-cycled," as it can be recycled over and over and over again. It is truly a cradle-to-cradle material.
Cradle-to-Cradle Life Cycle of Structural Steel
Structural Steel Mill
Overall carbon emissions have been reduced by 36% since 1990, and steel production has a water recycling rate of 95%, resulting in a net consumption of only 70 gallons per ton.
More than 1,700 steel fabricators in the United States supply fabricated structural steel for building and bridge projects; these fabricators purchase structural steel shapes and plates and fabricate the steel to meet the unique requirements of each project.
Construction and Erection
Steel is fabricated off-site to strict tolerances and can be erected quickly in the field, meaning fewer workers on the job site, safer working conditions, shorter construction schedules, and reduced emissions from construction equipment.
Long-span beams with open, column-free spaces attract potential occupants. In addition, steel framing can more easily be adapted for future changes in loading conditions, vertical expansion, and changes in occupancy when compared to other framing systems.
Beams, columns, and other structural steel elements removed from a building can be re-fabricated for use in new structures without having to be melted and rolled; the remaining steel elements are captured as scrap and used to create new steel products!
By weight, 81% of all steel products are recovered for recycling at the end of their life. This includes 85% of automobiles, 82% of appliances, 70% of containers, 72% of reinforcing bar, and 98% of structural steel.
Steel is the most recycled material in the world, with domestic mills recycling more than 70 million tons of scrap each year. Currently, structural steel includes 93% recycled content!
Need some inspiration?
These recent IDEAS² Award winners all have two things in common:
1. They're particularly conscious of the environment.
2. They're really cool!
Watershed Building, Seattle
Blue skies ahead for this office building and its stormwater treatment plant that can clean 400,000 gallons annually.
Canyon View High School, Waddell, Ariz.
Solar structures go back to school--throwing shade while providing 20% of the school's power.
Mori Hosseini Student Union | Embry-Riddle Aeronautical University, Daytona Beach, Fla.
Environmental Product Declarations
AISC develops industry-average environmental product declarations (EPDs) for three products: fabricated hot-rolled structural sections, fabricated steel plate, and fabricated hollow structural sections (HSS), with the latter developed in conjunction with the Steel Tube Institute.
These documents are designed to facilitate an accurate, apples-to-apples comparison of the structural materials on the market today. We update these EPDs every five years, and the most recent editions are hot off the presses!
Sustainable Characteristics of Structural Steel
- Recycled content of 93%, the highest of any building framing material
- Recycling rate of 98%, also the highest of any building framing material
- High strength-to-weight ratio coupled with a low carbon footprint (1.16 tons of CO2 per ton of fabricated hot-rolled steel) results in an overall reduction of the embodied carbon of a typical structure as compared to buildings constructed with other framing materials
- Significant potential for material reuse
- While other products can only be recycled into a lower-quality product (down-cycled), steel can be recycled over and over again and remade into new members without any loss of quality (multi-cycled). This makes it the first and only true cradle-to-cradle building framing material
- Superior water resource management: The structural steel making process boasts 95% water recycling rate with no external discharges, resulting in a net consumption of only 70 gallons per ton
- Increased productivity by a factor of 24 since 1980 (reduced labor hours per ton from 12 to 0.5)
- Increased material strength by 40% since 1990 (36 ksi to 50 ksi)
- Decreased carbon footprint (per ton) by 36% since 1990
- Decreased energy intensity (per ton) by 31% since 1990
- Decreased greenhouse gas emissions (per ton) by 45% since 1975
- Earned an EPA best industry performance designation
- Structural steel is fabricated regionally in off-site facilities to stringent tolerances, then erected on-site
- Minimal waste is generated at fabrication facilities and construction sites
- Any waste generated is fully recyclable
- Centralized, off-site fabrication minimizes employee travel
- Modern fabrication technology provides greater precision, productivity, and safety
- Steel members are efficiently transported by truck, rail, or barge
- Steel buildings are easily deconstructed, enabling reuse of the steel members
- Minimal, if any, ongoing maintenance is required
- Steel-framed buildings are highly durable and have a long life-span and are easily modified or expanded
- Steel framing allows easy integration of mechanical systems, resulting in low floor-to-floor heights, less building volume, and lower energy consumption
- Steel framing systems allow for large window areas, resulting in plentiful natural lighting, higher occupant comfort, and reduced electrical consumption
- A well-established, high demand for steel scrap ensures future reuse/recycling of a steel building frame
- As the electric utility grid becomes more renewable, the embodied carbon in structural steel will continue to decrease as the majority of steel's carbon footprint is due to electrical consumption in the steel-making process
- Research is underway on new production processes, with the goal of carbon-neutral steel
- The global steel industry is working together as a global manufacturing community to address sustainability issues, including environmental emissions
- The structural steel industry is committed to a sustainable future, and structural steel will remain the sustainable building material for generations to come
Steel Solutions Center
The Steel Solutions Center is for people who need technical assistance, innovative solutions, or tools to make structural steel design even easier.