Waste is a crime. Embrace your inner pragmatist and celebrate materials, methods, and technologies that do more with less.
Though sustainability rating programs such as the U.S. Green Building Council (USGBC)'s LEED have contributed fundamental knowledge on environmentally responsible material approaches in the AEC industry, future material strategies in green building demand a more significant effort to achieve measurable benefits. Next-generation material approaches must increasingly address material effects both within and beyond an architectural project. Significant improvements are possible at the intersections of traditional sustainable design—where materials meet energy, site design, and environmental equality. The following examples are suggestions for material strategies for architects to make a more significant contribution to building resilience.
Adapt and Reuse
A commonly held belief within sustainable design circles is that the greenest building is one that already exists, since relatively few new materials and energy are required for its use. By reusing existing structures, building systems, and materials, a design team can reduce environmental impact of a structure while, “creating successful cities and neighborhoods,” writes the National Trust for Historic Preservation (the Trust) in its Preservation Leadership Forum. Moreover, the Trust argues, “historic fabric creates economically vital, socially equitable, and strong, resilient neighborhoods.”
Increasingly, there are compelling instances of retrofit structures that once might have been considered raze-and-build projects. For example, Paris-based Local Architecture Network (LAN) decided to wrap a collection of unloved concrete towers in Bordeaux, France, in new skins of glimmering polycarbonate cladding. The decision avoided a massive demolition and construction effort, and the sliding translucent panels increase the versatility of the façade for users. To achieve full reuse potential, the architects could have specified repurposed or recycled materials for this envelope—including the plastic sheeting as well as the aluminum framing and connections. To create a truly reused and adapted design, an architect's default strategy at every scale—site, structure, and materials—should be to privilege the existing over the new. Of course, new products are always an option, but they should not be the first option.
Banking Carbon
The currency of sustainable design is carbon, yet we still treat it as an abstract concept based on estimates of how much carbon dioxide is produced throughout a material's life cycle. Although conceptual carbon accounting is an important process for measuring environmental effects, we forget that carbon is also literally stored within certain substances. While many building materials including steel, concrete, and plastics contribute measurable quantities of carbon dioxide to the atmosphere—resulting in poor environmental performance—biomass, such as wood or other plant materials, acts as a carbon sequester, storing more carbon than it releases. Unless the material decays or is destroyed, the carbon will remain embedded within. Buildings with a significant amount of biomass-based materials (sustainably harvested, of course) may therefore be viewed as carbon banks.
The recent surge of interest in tall wood construction is, in large part, a testament to the environmental appeal of “depositing” carbon versus effectively “withdrawing” it in a concrete or steel structure. To appreciate the difference, consider that mild steel has a carbon dioxide footprint of about 1.8 kg/kg (approximately 3.9 lbs./lb.) in primary production versus about 0.38 kg/kg for softwood (approximately 0.83 lbs./lb.)—nearly five times the contribution. The notion of carbon banking is exemplified in projects such as Beijing-based Penda’s 2015 Beijing Design Week contribution Rising Canes, an adaptable, multistory construction system that uses nothing but bamboo and natural fiber rope—two biomass products that require minimal processing and therefore maximize this kind of literal carbon accounting in architecture.
Follow the Light
The building envelope is a territory of continuous conflict: occupants require daylight, views, and fresh air, but these are only available at the expense of the thermal performance of the façade. It is commonly assumed that a window is a thermal hole—with poor insulative capacity compared with solid wall construction—and that more glazing equals more energy use, but less occupant comfort. However, not all light-transmitting materials have this problem.
For example, Boston-based chemical and performance materials company Cabot Corp. manufactures Lumira aerogel, a translucent, silica-based insulating material for a variety of glazing applications. Aerogel is more than 90 percent air, and because its microporous structure inhibits air molecule movement, it severely limits heat transfer. This advantageous characteristic results in energy savings and increased user comfort over standard glazing. Depending on the system, the aerogel delivers an R-value range from 6 to 20, which compares favorably with a typical R-24 solid insulating wall. (In other words, the aerogel-based envelope can almost provide the thermal savings of a solid insulating façade.) Although aerogel is not transparent, other glazing systems may be incorporated within aerogel-based façades for clear views to the outside.
Buildings as Energy Plants
Power distribution today is based on an obsolete model. The U.S. electricity grid is woefully antiquated: on average, power plants are more than three decades old and distribution grids more than 25 years old. “Not only do we have more outages than most other industrial countries, but ours are getting longer,” writes cultural anthropologist Gretchen Bakke in "The Grid: The Fraying Wires Between Americans and Our Energy Future" (Bloomsbury Publishing, 2016). Bakke and other critics of outmoded, centrally organized power networks advocate the more reliable and resilient combination of distributed energy generation and storage. To borrow a commonly advised financial investing strategy, we need to diversify our energy portfolio rather than rely on a single, vulnerable source.
For example, offerings such as Tesla’s Solar Roof tiles can facilitate the integration of renewable energy-generation into buildings. The glass-based, multifunctional tiles are designed to serve as a comprehensive substitute for conventional roofing materials. According to Consumer Reports, a typical detached house in a state offering green energy tax credits—such as New York or California—could save money with the Tesla Solar Roof after 30 years of use. And pairing this and similar products with building-integrated batteries will serve the increasingly critical needs for nighttime and peak-demand energy. Tesla’s Powerwall is a lithium-ion energy unit that stores 14 kilowatt-hours of power—enough for a one-bedroom house for a day—and may be grouped with up to nine additional modules. Mercedes-Benz, Nissan, and LG Chem offer similar products, suggesting that building-integrated power storage is a rapidly growing commercial niche. Once architects assume that buildings are responsible for both power-generation and storage, they can provide more reliable and sustainable energy to clients while alleviating pressures on a strained, predominantly fossil fuel–powered electricity grid.
Design Backwards
One of the most significant impediments to environmentally responsible construction is the notion that all buildings are permanent. “Most designers do not design with an end in mind,” write Fernanda Cruz Rios, Wai Chong, and David Grau, AIA, the authors of a recent Arizona State University, Tempe study on deconstruction. Despite incremental gains delivered by LEED and other environmental building programs, 160 million tons of waste related to building construction and demolition are disposed annually in the U.S.—about a third of the overall solid-waste stream. Design for Disassembly (DfD), a method that demonstrates an awareness of eventual deconstruction and employs measures to facilitate the process, is seen as a pivotal tool for reducing construction and demolition waste. The approach champions principles such as the use of standardized components and reconfigurable connections. However, there are currently few incentives, other than environmental altruism, for architecture firms to adopt such a practice. As a result, designers are considered to be the primary impediment in DfD planning.
An alternative approach is to include reverse construction considerations in the design process. in this method, every stage of material design and specification beginning with initial product surveys should include DfD valuations, and design teams should associate quantifiable metrics that factor into material selections. Construction documents should be viewed as having multiple lives and functions, informing not only how materials come together, but also how they can come apart. New tools are on the horizon that can ease the way for DfD tracking. One example is the Building Information Modelling-based Deconstructability Assessment Score, proposed by University of the West of England, Bristol research fellow Olugbenga Akinade and his colleagues, that will enable designers to measure the DfD potential of a project during the design phase.
Looking Forward
Today we are continually reminded of the importance of responsible environmental choices. The climate change-exacerbated devastation caused by Hurricanes Harvey and Irma has only punctuate this necessity for resilient design. Future strategies for building performance will increasingly combine material, energy, and other resource-related considerations to develop more holistic approaches to environmental design and construction. Thus far, we have targeted the “low-hanging fruit” of environmental material strategies; now comes the real work.
