Architects may be familiar with the concept of embodied energy, but they have long placed more emphasis on managing the energy that is generated while running the building, also known as operational energy. As structures are increasingly designed to be more energy-efficient, the relative percentage of energy embodied in the materials increases—and it’s important for architects to understand why.
The concept of embodied energy emerged out of early economic theory. In The Empire of Value: A New Foundation for Economics (The MIT Press, 2014), author André Orléan describes the “substance theory of value” that economists devised to ascertain the inherent quality of material goods for commodity exchange. Orléan writes that the theory arose from the belief that understanding this exchange requires going “beyond the surface appearance of commercial transactions, in search of a hidden property that is logically prior to such transactions and that gives them form.” In his 1973 article in the Journal of Theoretical Biology, “The Structure of Ecosystems,” Bruce Hannon declared, “In natural systems the currency is energy.” Hannon estimated a system’s total energy flow by tabulating all of its direct and indirect energy inputs. Meanwhile, a 2008 discussion paper by the Canadian Home Builders’ Association exemplifies the consideration of embodied energy in buildings, defined as the amount of energy required for construction and supplies, including all the energy used to produce the raw and manufactured materials required in a building’s construction.
Last week, a symposium at Columbia University’s Graduate School of Architecture, Planning and Preservation, in New York, shed more light on this concept and its potential implications in architecture. Organized by David Benjamin, an assistant professor there and founding principal of The Living, a New York–based research studio that was acquired by Autodesk in 2014, the day-long Embodied Energy and Design conference (at which I was also a presenter) put embodied energy in the context of broader design ecosystems and architecture. The event defined embodied energy as “the sum of all energy required to extract raw materials and then produce, transport, and assemble the elements of a building.”
The variety of dimensions addressed by the participating architects, engineers, manufacturers, and historians reveals that this seemingly simple concept can elicit wide-ranging and complex interpretations.
Sheila Kennedy, FAIA, professor of the practice of architecture at MIT and a founding principal of Kennedy & Violich Architecture, in Roxbury, Mass., emphasized that, as defined, the word "embody" has two key meanings: to contain or include something as a constituent feature, and to represent an idea or quality in visible or tangible form. This should be a reminder for architects, who typically regard embodied energy in the former sense without much consideration for its expressive potential in building.
Even when the term is examined exclusively according to the first meaning, clarifying its architectural implications can be difficult. Michelle Addington, a professor of sustainable architectural design at Yale University’s School of Architecture, revealed during her talk that the full impact of embodied energy in building construction is often unintentionally obscured in comprehensive reports by organizations such as the U.S. Department of Energy. The conventional Sankey flow diagram can be used to indicate energy consumption or carbon emissions by sector, but it typically separates buildings from industry; yet a substantial amount of industrial activity targets building construction. Thus, buildings have a much more significant role in global energy flows than commonly depicted.
Concerning material applications, many of the conference talks distinguished between technical and biological nutrient cycles, a concept outlined by the Cradle to Cradle Products Innovation Institute (C2CPII). A common theme for technical nutrients focused on the reuse of industrial materials with novel implications for architectural expression—a kind of re-embodiment of first-life energy inputs. Dirk Hebel, an assistant professor of architecture and construction at ETH Zürich, in Switzerland, described examples from his recent book, Building from Waste: Recovered Materials in Architecture and Construction (Birkhäuser, 2014), including ceramic tiles made from recycled coffee grounds, building panels that incorporate repurposed agricultural waste straw, and bio-composites made from recycling the paper and plastic components of self-adhesive labels. Andrew Dent, vice president of library and materials research at Material Connexion, in New York, offered several additional examples including a machine that recycles glass fiber-reinforced plastic, called The Polyfloss Factory, and bracelets made from recycled scrap metal from the Vietnam War. Such provocative resurrections of technical materials symbolize the forward-looking concept of embodied entropy discussed by Forrest Meggers, an assistant professor at the School of Architecture and the Andlinger Center for Energy and the Environment at Princeton University.
A Biological Focus
References to biological nutrients included living material applications as well as biological systems research. Eben Bayer, the co-founder of Green Island, N.Y.–based Ecovative, which makes products like packaging using the plant-based fiber mycelium, extolled the advantages of biological complexity in attaining high performance. Bayer discussed his cultivation of the mycelium-based materials for building insulation and packaging and described his company’s transformation of traditional industrial plants into centers for bio-based material production. Kennedy mentioned her evolving “sentient nature” collaboration with MIT chemical engineering professor Michael Strano, in which faculty and students incorporate carbon nanotubes into plants to enable them to fluoresce under particular conditions, allowing the plants to communicate via light. Paola Antonelli, the senior curator of architecture and design and director of research and development at the Museum of Modern Art, in New York, examined future design approaches that emphasize biological considerations, including “Designing for the Sixth Extinction," a project by London-based designer Alexandra Daisy Ginsberg that offers a provocative perspective on rewilding anthropogenically degraded nature using synthetic biology.
What Are We Measuring?
These examples illustrate the extent to which embodied energy is a generative concept within the architectural discipline, inviting speculation on a diverse array of ideas that emerge from a simple technical definition. This outcome is likely due to energy’s pervasive role in our environment. It’s necessary, therefore, for architects to know how and what to measure. Stephanie Carlisle, an associate and environmental researcher at KieranTimberlake, in Philadelphia, advocated for the development of a more accurate assessment of embodied energy in construction, asking, “How can architects design less-impactful buildings if they don't measure environmental impacts?” Chemist and C2CPII co-founder Michael Braungart, exacerbated this challenge by questioning the symposium’s focus, declaring, “We don’t have an energy problem, we have a carbon problem.”
In her concluding remarks, Antonelli shifted the conversation back to familiar territory: ourselves. While discussing the project 75 Watt, a film by Revital Cohen and Tuur Van Balen set in a mass-manufacturing Chinese factory, she advocated for increased scrutiny on the role of human labor. After all, the body is a fundamental component of embodied energy that is often missing from our calculations.