Have you wondered why most grocery stores stock large amounts of organic foods? The organic food market has increased approximately seven times over what it was a decade ago. Why the big change in this market? It comes down to simple supply and demand. The consumer has become better educated on how food is produced and is now demanding better alternatives. Although building materials are not “organically” grown, the structural engineer does need to become better educated on how materials they specify are made. The structural engineer is a major consumer of steel, concrete, timber, and other materials that we specify for the built environment. While we may not be the ones who purchase the material, we write the specifications for the materials used on a project.
While many areas of the construction sector have experienced dramatic contractions during the recent recession, sustainable or high-performance building design continues to expand. The expansion is driven by a combination of government mandates, owners realizing long-term savings delivered by energy-efficient buildings, and a heightened awareness of environmental issues among building occupants. Despite this progress, many structural engineers continue to be confused about how to participate in this movement or have become frustrated with the process.
The primary cause of this confusion and frustration is usually due to the manner in which most practicing structural engineers have been introduced to sustainability. In most cases, we have been involved with projects pursuing a USGBC LEED rating that rigidly followed the LEED scorecard and will usually result in a very prescriptive process that does not encourage innovative ideas. There is little the structural engineer can do to contribute to a LEED checklist. If you have not previously done so, review the LEED materials and resources credit submittals on one of your recent projects. You will likely see that concrete made a significant contribution as a regional material, and steel, either rolled or rebar, made a similar contribution to the recycled content. Then ask yourself if anything would have been different if the project had not pursued a LEED rating. This short-sighted assessment of sustainable design results in missed opportunities both for the structural engineer to make an environmental contribution and for you and your firm to serve your client.
The goal of LEED and other similar programs is not to maintain the status quo but to continuously raise the bar of environmentally acceptable design practices. Ten years ago, a LEED building was relatively unique, and few projects were pursuing the highest level of certification. Today, multiple buildings have achieved the highest level of certification, and owners as large as the GSA are looking beyond LEED to design “net-zero” buildings — those that produce as much energy as they consume. As buildings become more energy efficient, their operating impacts are significantly reduced; thus the relative environmental impact of the materials used to build and maintain a building becomes much higher. It is no longer enough to evaluate materials based solely on their recycled content or location of production. The structural engineer has to look deeper and ask what it takes to make a material in terms of both energy and emissions.
This is a change from how structural engineers have been trained to evaluate materials. We were trained to focus on the mechanical properties of materials, such as the grade of steel, the 28-day concrete strength, or the timber species. Today structural engineers must also understand where the materials specified come from, how they are made, and where they go after they are no longer used in a building. By becoming educated and demanding better alternatives to the current status quo of the supply chain, structural engineers will be instrumental in accelerating the transformation that is currently occurring in the marketplace.
Increase your knowledge of the supply chain
Currently, many building materials suppliers are seeking ways to differentiate themselves through environmental claims. We must become educated on the environmental issues associated with the supply chain so that we can advance the dialogue and ask the right questions.
The leading method to evaluate a broad range of environmental impacts is Life Cycle Assessment (LCA). LCA studies the material and energy flows associated with producing, installing, and disposing of products. As shown in Figure 1, the LCA process looks at all stages in the life of a material: raw materials, transportation, manufacture, installation, maintenance, deconstruction of the material, and recycle/reuse. You may be familiar with the term “carbon footprint” — a limited-scope LCA quantifying the carbon dioxide (CO2) emissions related to a product. Several recently available databases can quantify a material’s embodied carbon and other environmental parameters. Furthermore, ecological footprints measure more than carbon emissions. They can include particulate emissions, emissions leading to smog formation, or emissions of specific elements, such as mercury. These sources generally contain “industry average” data, which is helpful to understand the role the building’s structure plays in the big picture, but they do not allow top-performing producers to distinguish themselves.
How might we change our specifications or material approach? Consider steel. Currently, the vast majority of steel specified is produced by the electric arc furnace, and it usually has at least 90 percent recycled content. However, steel production still consumes a large amount of electricity, and the carbon intensity of that electricity is dependent upon the fuel sources used for production. In the United States, the CO2 emissions per kilowatt-hour can vary by a factor of two to three times depending on your location. Thus, two pieces of steel produced at different plants may have the same recycled content, but very different environmental footprints. This impact is not limited to the steel mill. “The Fabrication Factor” in the July 2010 issue of Modern Steel Construction (MSC) discussed the impact a structural steel fabricator can have on the overall footprint of a ton of steel. Author Geoff Weisenberger found that on average, the steel fabrication process contributes 20 percent of the steel package’s environmental footprint. However, depending on impact category, a “high-impact” fabricator can raise the impact by as much as 33 percent, and a “low-impact” fabricator can lower it by as much as 14 percent. Similar types of variations can be found for all material types and supply chains.
Although LCA is a complex, still-evolving process, there are tools available for the structural engineer to start looking at the ecological footprints for their building projects. As Frances Yang, P.E., LEED AP, discussed in “How to optimize the environmental performance of structural materials” in the August issue of Structural Engineering & Design, LEED is currently piloting a tool that uses LCA data to help design teams make more informed choices for structural and envelope materials. While most of the LCA tools available currently rely on industry average data, the structural engineer should be performing LCA because it is a significant leap forward from simply looking at recycled content and the location of material production. In addition, now is the also the time for structural engineers to look to the future of LCA and demand that individual material suppliers determine the ecological footprint of their products.
An excellent example of the type of information available comes from the carpet industry. Interface, a carpet manufacturer with a long-standing commitment to producing an environmentally responsible product, has performed LCAs to create Environmental Product Declarations (EPDs) for some of its products. An EPD (see Figure 2) is a concise third-party-verified report of product ingredients and environmental impacts due to production. These reports, which are available on Interface’s website, allow designers to compare the impacts of different products. If a supplier of a complex material like carpet can provide this type of environmental information, then it should be even easier for the structural engineer to find similar information for materials such as steel, concrete, and timber. We must start asking for this information so the suppliers are aware of the demand. While some suppliers may respond by saying that their operation meets all environmental regulations, we must remember that sustainable design is not about meeting the law, but exceeding current sustainable design practices. The next logical step for material suppliers would be a plant-specific certification process that provides a product’s ecological footprint numbers, similar to an EPD produced from companies like Interface.
It doesn’t matter if your firm is five or 500 people in size. The structural engineer can and will influence environmental design practices in the coming decade. If you want to be recognized as one of the leaders on the design team, you’ve got to start asking questions about where those products you specify come from and push down the supply chain. The next time a vendor comes to your office, or at the next project meeting, ask some informed questions; see sidebar below. Those surprised looks or responses like “We don’t have that kind of information” will eventually turn into action by the suppliers when they realize their competitors may be able to answer the questions. Also, do not fall for the trap of “there isn’t a LEED point for it.” LEED was designed to evolve, and the five LEED innovation credits were included for this very reason. Speak up in the design charrettes, make the case for specifying a better supplier, and quantify the benefit it brings. You might be surprised how your client — and their client — reacts. The structural engineer is a consumer conduit to most of these suppliers, and the rules of supply and demand will kick in.
Tough questions for material suppliers
Greg Briggs, P.E., S.E., LEED AP is a principal at Magnusson Klemencic Associates in Seattle, and is a founding member of SEI’s Sustainability Committee. He can be reached at email@example.com. Dirk Kestner, P.E., LEED AP is a senior associate at Walter P Moore in Austin, Texas and is chairman of SEI’s Sustainability Committee. He can be reached at firstname.lastname@example.org.
The Structural Engineering Institute (SEI) Sustainability Committee, which both authors helped establish more than 5 years ago, has written a reference guide titled, Sustainability Guidelines For the Structural Engineer that is expected to be available fall 2010 from ASCE Press. To learn more about the committee go to www.seisustainability.org