Conversations about sustainability typically prioritize issues of energy consumption and global warming. But at a sustainable-engineering conference hosted earlier this month at The Ohio State University (OSU) by its Institute for Materials Research, the spotlight was on materials. Engineers, scientists, economists, historians, and architects convened at Materials Week from May 12 to May 15 to learn about the latest discoveries in sustainable materials research and to discuss novel strategies for more responsible resource utilization—with the results suggesting that architects should consider material sustainability a greater part of their mission.
The event’s materials theme was based on the fundamental role of physical resources in shaping industries. “Materials are technology enablers,” said Martin Green, a materials research engineer at the National Institute of Standards and Technology (NIST), in his talk, “Sustainable Materials for the Anthropocene.” He argued that there would be no Information Age without silicon, no mobile phones without functional ceramics, no skyscrapers without steel girders, and no solar conversion without photovoltaics. “Sustainable development is not possible without the involvement of the materials community,” he said.
Green and other researchers reinforced the importance of materials in achieving a true cradle-to-cradle economy while noting the challenges of achieving such a difficult goal. Although most of the event’s presenters came from outside of the AEC sector, the trends and strategies they outlined have clear implications for buildings and infrastructure.
A common theme among the talks was the growing scarcity of nonrenewable resources. In his presentation, “The Periodic Table of Criticality,” Yale industrial ecology professor Thomas Graedel outlined the bleak outlook for metals. His comprehensive analysis considered the ill-fated combination of accelerating global demand and diminishing supplies. Worldwide per-capita use of many metals has increased dramatically within the last century. For example, chromium is mined 100 times more now than in 1908, and aluminum more than 1,000 times for the same period. In addition, the use of larger quantities and more varied types of metals has increased, including many rare elements that are not mined directly but instead are byproducts of primary metal mining. For example, iridium, which is used in a variety of medical and industrial applications for its corrosion resistance, is harvested from nickel mining. Meanwhile, the production of many metals is either stagnating or declining despite continued exploration, suggesting that their most accessible reserves have been exhausted.
Graebel's periodic tables of criticality for 62 metals. From top, A) supply risk, B) environmental implications, and C) vulnerability to supply restriction.
Graedel further clarified several misconceptions about metal use. “If something is scarce, why don’t we get it from recycling?” he asked in his talk. Although metal recycling is a resourceful practice, it has two primary challenges. First, many metals have poor end-of-life recycling rates: of the 60 periodic table metals studied by Graedel and his colleagues, only 18 exhibited recycling rates above 50 percent. Second, recycling flows will not be able to keep up with the total flow of material use if consumer demand continues to grow. He shared a material quantification method that he helped to develop at Yale called “Lost by Design,” which reveals the challenges presented by in-use dissipated and currently non-recyclable components of metals in industrial processes. Graedel addressed the common question of substituting a more plentiful material for one that is scarce by revealing the practice’s inherent inefficiencies.
Regarding metal criticality, NIST’s Green explained two approaches to improving material efficiency based on resource performance. The first is lightweighting, or reducing the overall material volume in an application, with the resulting construction achieving the same ends with less resource input. The second method requires reducing the amount of environmental impact for the same volume of material. Both methods are directly applicable to architecture. The former is an approach often recommended by Buckminster Fuller, who asked architects to consider the weight of their buildings carefully. The latter is demonstrated by the use of more environmentally responsible materials, such as low-embodied-energy concrete and recycled aluminum. Although Green didn’t mention it, these methods can be combined for further benefits—for example, lightweighting with 100 percent recycled aluminum.
Green’s other suggestions concerned the end of a material’s life. Scraps are not waste, but rather “materials out of place,” he said, adding that it is especially important for critical materials to be recycled due to their scarcity and citing what he calls a “no-build periodic table” and related products that, in the absence of specific critical elements, simply cannot be manufactured. He also spoke of composites—hybrid materials that are extremely difficult to separate into their original materials—as challenging recycling efforts. He called out three areas of promising research: thermoelectric materials that convert waste heat into energy, carbon-dioxide capture technology, and windows that use thermochromic technology to regulate solar-heat gain.
Construction on Buckminster Fuller's former geodesic dome residence in Carbondale, Ill., in 1960. The architect encouraged minimal material use in his structures.
Beyond these episodic approaches, however, a proposal by OSU chemical and biomolecular engineering professor Bhavik Bakshi offers a provocatively holistic vision for future industrial ecologies. In his talk, “Towards Techno-Ecological Synergy: Life Cycle Design of Sustainable Material Systems,” Bakshi described a new, comprehensive strategy for working responsibly with natural systems. His ambitious approach seeks to couple human industry directly with natural ecologies such that all material and energy flows are tracked and balanced. This idea extends from the concept of ecological goods and services—such as the provision of renewable biomass, phytoremediation, and carbon-dioxide sequestration—and aims to quantify these services in terms of measurable attributes such as raw material volume and economic value.
In Bakshi’s view, every technological system would be matched with an ecological system so that the latter’s natural services could be employed without its overuse or degradation. Although the idea’s implementation would be a daunting task based on the sheer quantity and complexity of data to be measured, the proposal provides a refreshing strategy for the responsible implementation of cradle-to-cradle practices at a local level.
Materials Week conveyed valuable insights for architecture, as captured in Green’s comments about sustainable development and the materials community. Based on buildings’ utilization of nearly half of global resources and architects’ role in specifying those materials, one could easily conclude that sustainable development is not possible without the involvement of architects.
In order to contribute meaningfully to this goal, architects must look beyond environmental tracking methods like LEED—which are inwardly focused on projects—and adopt an understanding of global resource trends that are conventionally considered external to projects. Such a broad outlook could lead to beneficial new design strategies and policies—for example, the avoidance of building products that employ high percentages of critical metals or the coupling of a building’s resource budget with services provided by its local ecology.
According to Bakshi,
80 percent of global ecosystem services have been degraded, and anthropogenic
biogeochemical cycles have overwhelmed the capacity of natural ecosystems. While
developing broad material sustainability expertise may seem beyond the duties
of the architect, it must become a part of the job description.
