Structuralengineers face significant challenges in the 21stcentury and among them, globalenvironmental challenges must be a priority for our profession. On a planet withfinite natural resources and an ever-growing built environment, engineers ofthe future must consider the environmental, economic, and social sustainabilityof structural design. To achieve a more sustainable built environment,engineers must be involved at every stage of the process. To address thebroad issue of sustainability for structural engineers, this paper is dividedinto three sections: 1) Global environmental impact: The trends in steel andconcrete consumption worldwide illustrate the growing environmental impact ofstructural design. In particular, the emissions of greenhouse gases due tostructural materials are a primary global concern that all structural engineersshould consider. 2) Solutions for today: There are many steps thateach structural engineer can take to mitigate the environmental impact ofstructural design.
Furthermore, there is growing demand for engineers who areknowledgeable of environmental issues in construction. This section presents severaloptions that are available today for engineers interested in reducingenvironmental impacts. Case studies will illustrate examples of more sustainable structural design. 3) Challenges for the future: Although short-term solutionsexist to reduce the environmental impact of construction, there are significantlong-term challenges that we must address as a profession. By facing thesechallenges, we can take a leadership role in matters of vital global importance. In summary,the paper identifies the global sustainability challenges facing our professionand suggests possible solutions.
The conclusion is that structural engineeringhas an enormous global environmental impact and our profession should workharder to offer solutions to society. Working for a more sustainable builtenvironment is in the best interest of our profession as well as the interestof future generations. 1 Global Environmental Impact On a planetwith finite natural resources, the human population is growing and the rate ofresource consumption per person is growing. This cannot continue indefinitely.In 1974, a landmark study by aninterdisciplinary research group at MIT illustrated the various globalscenarios that may occur depending on a range of possible technological,economic, and social assumptions (Meadows et al. 1974).
Almost all of thepossible scenarios predicted a collapse of natural resources followed by acollapse of human populations and decreased quality of life. Recently, a30-year update reconfirmed the key conclusions of this study and illustratedthe grave challenges facing global society in the future (Meadows et al. 2004).Increasing greenhouse gas levels, rising global temperatures, rising sealevels, and dramatic resource depletion have all occurred at increasing ratesin the last 30 years. The growingneed to address these challenges has become more accepted in the last decadeand civil engineers have begun to play an important role. Since the 1987Brundtland report defined sustainable development as meeting “the needs of thepresent without compromising the ability of future generations to meet theirown needs,” the concept of sustainability has become an ethical standard and agoal for both government and industry (Brundtland 1987). Though civil engineershave not provided global leadership on this issue in recent decades, it isclear that the profession of civil engineering will play an integral role inachieving more sustainable development in the future (ASCE 2001). Over the last200 hundred years, the definition of civil engineering has evolved from”directing the great sources of power in Nature for the use and convenience ofMan” (Chrimes 1991) to a more recent definition that “Civil engineers are the custodians of the built and naturalenvironment” (Agenda 2003).
This shift illustrates the fundamental change inthe relationship between engineers and the natural world. Man and nature arenot separate entities. Engineers today must design for a planet with limitednatural resources, complex problems with no clear answers, and increasing environmental concerns. As a testament to the growing awareness ofsustainability for structural engineers, the International Association ofBridge and Structural Engineers (IABSE) dedicated a recent issue of Structural Engineering International tosustainable engineering design.
In particular, the emissions of greenhousegases due to structural materials are a primary global concern that allstructural engineers should consider. The trends in steel and concreteconsumption worldwide demonstrate the growing environmental impact ofstructural design, as illustrated in Figure 1. The production of Portlandcement has doubled in less than 30 years, and this exponential growth isexpected to continue well into the next century (Chaturvedi and Ochsendorf2004). Furthermore, each ton of cementis responsible for approximately one ton of CO2 emissionsand the cement industry alone contributes about 7% of global CO2 emissions.2