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Metals Compared to Wood for Sustainable Construction
1/11/2012
Alexis Karolides, AIA
Metals have become such a common element in so many building applications, from nails to plumbing fixtures, that it would be hard to imagine building without them. Metals are strong, durable, and generally do not cause indoor air quality problems. (Airborne dust from lead paint is a notable exception.)
Sometimes metals are just one of several viable material choices, in which case it is instructive to compare options. Structural framing is one such example. The debate over which is the “greener” framing material—steel or wood—has no unanimous resolution. Although steel is highly recyclable and its raw materials are plentiful, wood is a renewable resource, is recyclable and biodegradable, and has much lower embodied energy than steel (even recycled steel has five times the embodied energy of kiln-dried wood). Wood is also a natural insulator, whereas steel is a conductor. (It is 400 times more conductive than wood.) The “thermal bridging” that occurs at exterior walls where steel studs span from the inside out can halve the overall R-value of a wall with cavity insulation (as compared to the R-value of the same wall framed with wood). This presents a major energy-efficiency problem for steel-framed exterior walls. Providing a layer of continuous exterior insulation, while it does not completely solve the thermal bridging problem, can significantly increase the overall R-value of the steel-stud wall.
On the other hand, steel framing is lighter than wood, more regular and dimensionally stable, and offers the advantage of resistance to insects. It does not require (as wood does) treating the soil with termiticides, and therefore is better for air quality. Steel is easily separated at the demolition site using a magnet, and steel scrap has a ready market. The overall recycled content of U.S. steel (on average for all steel products) is 46%, but this doesn’t account for the steel scrap that is exported (11% of the total manufactured steel) rather than re-manufactured in the U.S.
Both the wood and steel industries have caused serious environmental problems. Clear-cutting forests has caused habitat destruction and siltation of streams (and pesticide-laden, monoculture plantation forests are not much of an improvement). Strip-mining for the iron and limestone used in steel has caused severe erosion, ecosystem destruction, and leaching from tailings piles into water systems. Fortunately, both industries are making environmental and efficiency improvements.
In an application that allows the use of either wood or steel (especially if untreated wood can be used), wood from a certified, well-managed forest would be the most environmentally sound choice. Overall, its manufacturing process uses much less energy and creates less pollution and environmental degradation than mining and processing steel.
The mining and manufacture of other metals presents environmental concerns similar to those associated with steel, and often much more severe. For instance, the embodied energy of copper is about twice that of steel, while virgin aluminum has as much as seven times the embodied energy of steel.
Like steel, other metals used in building are highly recyclable. Although remanufacturing metals uses significant energy, it is much less than the energy and environmental impacts of starting with the virgin resource. Because metals are highly durable and could be recycled indefinitely, their environmental impact (extraction from the earth and the fact that they are nonrenewable resources) is significantly reduced.
Finally, metals offer clear advantages for certain applications. For example, if water collected from a roof surface is to be used for drinking, a steel roof will not leach petro-chemicals into the water, as an asphalt-based roof might. Although stone or clay tile roofing could also be used, their greater weight would require more structural support than the lighter steel.
Alexis Karolides, AIA, the author of this article, is a registered architect and principal with the Rocky Mountain Institute (RMI) in Snowmass, Colorado. This article was adapted from Green Building: Project Planning & Cost Estimating, 3rd Edition, available through RSMeans.
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Thoughts for Today
1/11/2012
Trust in the Lord with all your heart; do not depend on your own understanding.
Seek his will in all you do, and he will show you which path to take. Proverbs 3:5,6 (NLT)
When the body dies, the spirit lives on forever. Where will you spend eternity? Either with God or in
eternal torment. "If you confess with your mouth Jesus, and believe in your heart that God has raised him
from the dead, YOU SHALL BE SAVED!" Romans 10:9
Commit to the Lord, whatever you do, and your plans will SUCCEED!
Prov. 16:3 (NIV) (This really works!!)
There is a lot of talk today about "Real Americans". However, we all have to respect the Native American Indians.
Like the two braves who were visiting New York City for the first time and a little old lady went up to one of them
and asked, "Are you a real Indian?"
"Yes, ma'am," answered the Indian.
"How do you like our city?" asked the lady.
"Fine", the Indian said. "How do you like our country?"
The fire fighters at the local firehouse got a call one night just after they had settled down for some sleep.
"Its an awful fire," cried the caller. "MY HOUSE IS BURNING DOWN!" "Did you throw water on it?" asked the chief.
"Yes!" yelled the caller. "But it didn't help!" "Well," said the chief, "there's no use in our coming over then. That's all we
were going to do." "Goodnight."
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Tri-State
Cold-Formed Steel Components was formed in 2003 with a shared
mission to be the best supplier of cold-formed trusses and related
components.
With a lot of faith and experience and even more hard work,
this team set out to accomplish its mission by offering very
competitive prices without sacrificing quality.
The commitment to our customers is evident in the way we communicate
with them and increase their bottom line through value-added
ideas and solutions. The independent testimonials of our customers
speak for themselves. There is
no reason to expect your experience to be any different. Give us
a call today! |
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Stuart
C. Melvin, President & CEO
Over the past 20 years, Stu has held positions of increasing
responsibility in the financial and operations management of
manufacturing organizations. These positions include Accounting
Manager, Materials Manager, Plant Manager, Corporate Controller,
Chief Financial Officer, and General Manager. He has a BS degree
in Accounting from North Carolina Central University. His experience
is gained from a broad spectrum of industries including financial
services, metal fabrication, chemical manufacturing, biotechnology,
and truss manufacturing. His leadership is the driving force
behind Tri-State CFS emphasizing teamwork, quality, value-added
customer service, and growth. |
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Karen Bickett, Design Administrator
Karen has over 10 years of progressive experience in customer relations. She has a thorough knowledge of truss design and job layouts and assists with all phases of the orders including preparing and coordinating sealed engineering drawings, expediting shop drawing approvals, and coordinating product delivery. Karen's personality and eagerness to solve problems is a matchless combination for delivering outstanding customer service. |
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Ed
French, Vice-President Operations
Ed has over 15 years of design experience in the truss industry.
He has a degree in Architectural Design from State University
of New York – Delhi and has been involved in the startup
of several truss manufacturing operations. Ed has been directly
involved with the Alpine TrusSteel product since its conceptual
development and inception. He has over 10 years of experience
in truss manufacturing design management and steel truss operations.
Ed utilizes Just-in-Time and Lean Manufacturing production strategies
to maximize efficiency and reduce operating costs. |
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Troy
Lutgens, Vice-President Engineering
Troy started in the truss industry as a production line leader
for a wood truss manufacturer. After completing a BS degree
in Physics from Lock Haven University (PA), he was promoted
to Designer. Troy has held the position of Senior Steel Truss
designer for 10 years. His strength is in his ability to communicate
directly with contractors, architects, engineers, and builders.
His thorough understanding of construction standards and roof
designs creates value-added solutions and cost saving ideas
that directly benefits the customer. He is currently completing
his degree in Civil Engineering-Structural Design from the University
of Louisville. |
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Steve
Beck, Vice-President Finance, Controller
Steve brings over 25 years of experience in financial management.
He has a BS degree in Accounting from the University of Louisville.
Steve is a solid hands-on Controller and has over 15 years experience
in manufacturing and construction project accounting. His extensive
experience in job costing, financial management, and information
systems comes from a variety of industries including construction,
electrical contracting, transportation, personnel services,
and truss manufacturing. |
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