Reusability by Design
In the Netherlands, material conservation policies have resulted in the recovery of about 80 percent of its 15 million tons (14 million metric tons) of construction and demolition waste for reuse in other structures. The Dutch, perhaps culturally attuned to the limitations of space and material, passed legislation in 1997 that essentially states that "dumping of reusable materials is prohibited."
Putting Theory into Practice
The deconstruction branch of a BRING Recycling a local nonprofit in Oregon, is an example of the growing industry based on carefully dismantling buildings. "Components like cabinets are generally easy to remove and resell quickly," says business manager David Wollner. Contemporary windows, doors, and other fixtures that can be removed whole also resell well.
As his crew methodically takes apart a small house, supervisor Alec Maxson explains that material recovery is affected by the fastener types used in the original construction. "If a project uses a lot of glues — like this manufactured home — then often reuse is out of the question." The aluminum siding will have to be sold for scrap because nails and a glued backing make it impractical to remove intact.
Designs that avoid glues and rely on mechanical fasteners such as screws make disassembly more practical. The more the building can be organized into discretely reusable components, the more value those elements will have in the future. Frame structures limit the number of connections and structural pieces and are easier to dismantle.
Evaluating the Effects
Conceptual frameworks can also affect design to reduce waste. The "theory of layers" proposes that buildings be conceived as a series of related layers, each with its own life span. With thoughtful design, a layer can be separated, both theoretically and physically, and then reapplied or recycled according to its usefulness. In his seminal book on building adaptability, How Buildings Learn, Stewart Brand proposes six layers: site, structure, skin, services, space plan, and "stuff."
For example, if the layer "stuff" is movable furniture, it can be changed rapidly, while a well built structural layer might last centuries. The design of building components and their interfaces is critical to applying this theory successfully.
Brand's book describes in depth the lessons he draws from historic buildings, and he quotes Frank Duffy, the British architect and theorist: "Thinking about buildings in this time-laden way is very practical. As a designer you avoid such classic mistakes as solving a five-minute problem with a fifty-year solution, or vice-versa... It means you invent building forms which are very adaptive."
Researcher Philip Crowther of Queensland, Australia emphasizes the importance of considering recycling hierarchy. The dominant model of building life cycle has materials moving in a linear progression from extraction and processing to demolition and dumping. The alternative to this paradigm is a nonlinear progression with materials reintroduced into future building cycles. When a material is recycled into a less organized, less valuable form — like concrete crushed into fill — significant waste may still be incurred, even as the tons to landfill are reduced.
Whole-building reuse is the most efficient form of recycling. Adaptive reuse can happen in place, or in some situations with relocation of the entire building. Component reuse is next in the hierarchy: reapplying a component such as a panel system or cladding to another project.
Material reuse is the reprocessing of materials for new uses; for instance, heavy timber can often be remilled to suit with direct cost savings compared to buying new timbers. A residence designed by the author uses redwood siding recovered from California wine vats, cypress paneling from "sinker" logs recently recovered from the mud of Louisiana, reused high school bleachers for pine flooring, and stone from an old mill.
At the bottom of the recycling hierarchy, when buildings, components, or materials can't be reused, they may still be recycled and made into new materials. For example, concrete can be crushed to make substrate for roads, and plastics can be refashioned into new products.
A big challenge is to encourage designers and clients to invest today in making resources accessible even though the benefits won't be realized until future decades. Programs such as LEED certification could develop such incentives. Currently, LEED points are available for recycling material but not for designing for disassembly.
Legislation like that in Europe might ultimately be necessary to ensure that resources aren't squandered and that designers take responsibility for making materials accessible in the future.
If this sounds like a recipe for soul-stifling regulation, consider the example of traditional Japanese architecture, which embodies many principles of design for disassembly. The timber framework minimizes the number of connections needed, and the intricate joinery requires no fasteners. Based on the module of the tatami mat, floor plans are noted for their ability to change, adapt, and expand. Traditional Japanese lightweight natural materials do not require much processing, and they are healthy and beautiful.
Professor Charles J. Kibert of the University of Florida writes: "The main problem facing deconstruction today is that the architects and builders of the past visualized their creations as permanent and did not make provisions for their future disassembly." Concerned designers should begin now to incorporate the basic concepts of making buildings flexible, adaptable, and reusable.
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Michael Cockram is an adjunct assistant professor of architecture at the University of Oregon. He is the director of the Italy Field School Program.