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As structural engineers, our role in sustainable design has expanded largely due to increased demand by building owners and the public for greater efficiencies, which makes it both an exciting and challenging time to be in this profession. Sustainable issues are much more global in nature, and of course, much more prominent among the AEC community due to the leadership of the U.S. Green Building Council and its Leadership in Energy and Environmental Design (LEED) rating system.
The LEED rating system and other similar programs — such as BREEAM, Green Globes (GBI), and Building for Environmental and Economic Sustainability (BEES) — has elevated sustainable conversation and influenced the articulation of sustainable structures worldwide. Yet the sustainability success of a project should not be measured strictly upon these rating systems because sustainable goals and opportunities should be project specific.
As a result, our charge as structural engineers is to ensure that the sustainable goals and the building design strive for higher levels of achievement. If we simply relegate ourselves to discussions of recycled steel or fly ash in concrete, we commit ourselves to a pedestrian and rather environmentally insignificant future.
The future of sustainable design mandates changes today that will affect our traditional building processes and codification. And in order to define and actualize these new conventions, we can no longer think conventionally.
Performance-based versus prescriptive codes
Performance-based building regula-tions can be traced back to King Hammurabi who ruled Babylon from 1792 B.C. to 1750 B.C. During his reign, Hammurabi established specific, performance-based building codes, one of which is inscribed upon a stone currently in the Louvre in Paris. In short, the code says if you construct a building that falls down and harms someone, you will be put to death. Now, that’s a serious performance-based code!
While the United States is making progress to adopt performance-based code provisions, we are still behind some other countries. This constitutes a larger policy discussion, but in terms of sustainable design trends of the future, we must begin the conversation with our leaders. To do so will require a mind shift of great proportions. We will need to rethink what can and cannot be allowed in terms of building codes while maintaining an emphasis on engineering safe, sustainable structures.
We cannot hamper the great wealth of creative thought that structural engineers possess. We have seen great strides in the area of seismic engineering, which will result in more efficient and thus more sustainable structures, and we need to expand that creative thinking to other areas.
The role of adaptive reuse
Currently, the model building codes allow building officials to permit the reuse of existing structures, without upgrades, provided there are no adverse safety ramifications. These provisions are keys to allowing the adaptive reuse of our nation’s extensive stock of existing buildings, provided the new use does not impose increased loading on a structure. While these are long-standing provisions in model codes, many do not take full advantage of this, when appropriate, to justify the continued use of an existing structure.
The preservation of an existing structure is the ultimate in sustainability. With today’s advances in material choices, such as fiber-reinforced polymers, it is possible to save an existing structure and reduce the carbon footprint produced from demolition. Although cost is always a consideration, many of these structures can be converted into sustainable, cost-effective structures by using alternative materials.
In order to equitably compare the development approach when dealing with an existing structure, we need to reconcile the environmental impact of the demolition and replacement of the structure with the impact of a new structure. If we are serious about creating a sustainable future, it is incumbent upon us as structural engineers to provide a sum total of the project at hand.
Integrating hybrid systems
In order to remain relevant, the professional mindsets of structural engineers cannot be perceived as static. If we are to advocate for sustainability, we must engage ourselves at the earliest stages of design. As options are considered, we can help to identify materials that are regionally specific and efficient; we can suggest sustainable methods for preserving or deconstructing a building, depending upon its future use and related project costs and budgets; and we can develop structural systems that are efficient and relevant to the form and function of the facility.
Traditionally, the North Texas region is a strong concrete market. With five plants in a 6.5-mile radius, the nation’s largest complex of cement manufacturers is located just south of Dallas/Fort Worth in Midlothian, Texas. In addition, Texas has a ready supply of fly ash from the fossil fuel power plants, an ample supply of quality aggregate, and easy access to reinforcing steel. However, if we consider the entire environmental impact related to the production and procurement of these materials, it does not always represent the most sustainable approach to structural construction.
We need to be open to changes in materials and design approaches that may offer greater sustainability. Hybrid systems combining the use of regional materials configured to take advantage of their best structural properties can offer strong, sustainable options. For example, engineered timber products produced from rapidly renewable forests can be combined with high-strength steel to create efficient, architecturally pleasing trusses. Natural stone in combination with steel cabling can be utilized instead of cast stone or precast concrete with conventional steel framing to create architectural elements such as sunscreens.
Paradigm shifts in theconstruction industry
As architectural practices trend toward exposed structures and eliminating finishes, the building structure becomes more of an architectural statement. For example, the use of exterior sunshading for reductions in energy consumption helps define the exterior space of the building. These trends allow the structural engineer to highlight his work and creativity, and do more than just engineer the skeletal element on which everything is built.
From a sustainable viewpoint, building information modeling (BIM) represents the future. BIM enables every component of the building to be modeled for efficiency. When the structure becomes part of the architecture, the structure has to be modeled to see how the systems interrelate.
Changes in the methods by which we conduct business can also have sustainable benefits. For example, the shift from traditional CAD to BIM can and should result in a more efficient methodology for the production of not only our work, but the work of the entire project team. BIM means less paper and more collaboration, and it has the potential to bring the entire project team, including the contractor and the sub-contractors, together.
For structural engineers, the greater our ability to collaborate using BIM, the more efficient we become and the smaller our carbon footprint. The good news is that in many cases structural engineers are leading this transition.
The need for advanced education
As structural engineers, we cannot take a back seat on the road to the future. We must lead, and to that end, leadership skills must be cultivated. LEED training has provided a solid platform for a sustainable education, but LEED credentials are just one part of the future.
The balance lies prior to launching one’s professional career, at the university and college level. We need to support higher education as it raises the bar for both sustainable education programs and interdisciplinary studies. Many universities are already doing this, but they need more industry support and guidance to achieve their goals.
For example, Jaster-Quintanilla, Dallas (my firm), established the first graduate fellowship in sustainability at Texas A&M University (my alma mater), and although the first recipient is studying water resources, we hope the next will study advanced structural materials or historic preservation.
Conclusion
How can we as structural engineers contribute to sustainable design in the future? First, we cannot be passive about sustainability. We are uniquely positioned to take a seat at the table and have a strong, compelling voice. In other words, we must explain the impact on the community-at-large, to the community-at-large.
Second, we need to be strong advocates for education. We cannot operate in silos; we must be moving toward collaborative and interdisciplinary project work. The best structural engineers of the future will need to see the interrelationships and their value among the entire project team.
Third, we can’t fear conversation about the legal side of building codes. We need to support performance-based ordinances. We need to push for sustainable solutions that are serious, safe, and non-traditional.
Finally, we must walk the talk within our own companies. How do we run our firms from a sustainable point of view? Are we sending out the best messages about sustainability by recycling, renovating our offices, and using paperless technologies? If it is to be taken seriously, sustainable leadership must pervade a company’s culture from top to bottom.
The future of sustainability will not be about LEED credits for a bike rack and a shower or a low-flow toilet. The future will be about the whole building envelope and its inherent design that reduces our carbon footprint. By leveraging our structural expertise to engineer efficiently designed and aesthetically pleasing buildings that benefit the community as much as the owner, developer, or facilities manager, we will become champions of a sustainable future.
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Stephen H. Lucy, P.E., is managing principal of Jaster-Quintanilla Dallas LLP (JQ) in Dallas. The firm is recipient of multiple awards for engineering excellence and best practices, among them “Best Green Project in 2008” for JQ’s structural engineering services for the Trinity River Audubon Center in Dallas. JQ has also been a Pinnacle Award winner for the past two consecutive years. Lucy can be reached at slucy@jqeng.com.
