A colleague explains why sustainability is not on his agenda: "When I receive a floor plan from an architect, my job is to crank out the cheapest framing scheme. Most of the decisions regarding sustainability are out of my hands." Despite the growing popularity of green buildings, many structural engineers have no idea how to incorporate sustainability into their projects. The checklist-based Leadership in Energy and Environmental Design (LEED) rating system set forth by the U.S. Green Building Council contributes to this problem. The tenets of LEED depend largely upon the work of the architect, mechanical engineer, and general contractor. This is not to say that the goals of LEED are not worthwhile; however sustainable thinking for structural engineers is much broader than the current scope of LEED.
Structural engineers assisting their clients with LEED certification often walk away with one action item: use a fly ash or ground-granulated blast furnace slag in the concrete mix to contribute to recycled content. Other credits that require additional structural involvement, such as building reuse and resource reuse, have been achieved less than 5 percent of the time, according to the report, Costing Green: A Comprehensive Cost Database and Budgeting Methodology by Lisa Fay Matthiessen and Peter Morris (Davis Langdon, 2004). As the design team pursues the "easier" LEED credits, opportunities for contribution by the structural engineer get sidelined. Sometimes we work to accommodate green design strategies such as daylighting or under-floor air distribution, but structural design has much more to offer than simply reacting and accommodating.
The impetus for structural engineers to put sustainability on our agenda will partially come from the changes taking place within the building industry and market forces surrounding the growing scarcity of resources. But the motivation must also come from our understanding of the environmental burdens we are placing on our planet and the drive to create better buildings: we must pursue structural engineering "best practices." Is it best to provide what a client or owner is asking for if the result has a negative impact upon our natural environment? A report completed by the American Society of Civil Engineers’ (ASCE) Committee on Sustainability (Sustainable Engineering Practice, 2002) maintains that we are living in "The Century of the Environment" and that the environment will be the primary challenge facing the engineer of our times. Have we expanded our definition of structural engineering "best practices" to include advancements that confront the challenge of this century?
There is no structural practitioner’s checklist for sustainability; however there are many simple strategies, as well as larger shifts in how we design, that can be, and have been, accomplished. A new committee was formed last year within the ASCE Structural Engineering Institute (SEI) to advance the understanding of sustainability in the structural engineering community and to incorporate concepts of sustainability into structural engineering standards and practices. The committee is currently preparing detailed articles and compiling references on some of the topics listed below.
Simple strategies for today—These strategies include passive practices such as material optimization—using no more material than is prescribed by code or good engineering judgment. To a large degree, structural engineers already do this, but we must challenge ourselves to use materials even more effectively. It is imperative to specify materials and products that do not have toxic effects on human health and the biosphere. Structural engineers should collaborate with architects and specifiers to ensure that sustainable practices such as local sourcing of materials, use of wood from sustainably managed forests, and recycled content minimums are successfully incorporated into projects. And our early pre-schematic involvement contributes to integrated designs that decrease the energy, material, and fabrication costs associated with highly welded, stiffened, braced, or reinforced structures.
Larger shifts in how we think and design—It is not only vital for the structural engineer to understand and embrace the general principles of sustainable design, but also to promote more advanced ideas in their practice. Obtaining salvaged materials and assuring their quality for reuse is typically not an easy task, but the industry is making great strides on this front. Designing new structures for deconstruction or salvageability requires significant foresight to enable a building to be easily disassembled and reused or recycled. Truly sustainable structures would ensure that every material at the end of a building’s life will either be recycled or safely biodegrade, leaving no toxic trace or long-term landfill mass.
There are convincing reasons for us to take an active role in developing the tools and alliances that will advance sustainable goals. As design professionals, why should we wait any longer for market forces to drag us forward when many of the solutions to the challenges of our time fall under the realm of our professional practice? Structural engineers have only begun to innovate, design, and build to their potential.
Carla Dhillon, P.E., LEED AP, is a project engineer for Lionakis Beaumont Design Group, an A/E firm with its headquarters located in Sacramento, Calif. She can be reached at Carla.Dhillon@LBDG.com. Ruben Aya-Welland, S.E., P.E., LEED AP, is a project engineer for Hellmuth, Obata + Kassabaum (HOK), a multi-disciplinary architectural firm headquartered in St. Louis, Mo. He can be reached at firstname.lastname@example.org. Dhillon and Aya-Welland are both members of SEI’s Sustainability Committee. The committee website is www.seinstitute.org/committees/sustainable.cfm