Single-use items are prominent within the current conventional design strategies in the U.S. Almost nothing we buy is deconstructed, repaired or refurbished and then reused in buildings.

It doesn’t have to be this way, though. As stewards of the natural environment concerned about the effects of toxins and climate destabilization, we need to do better. As designers of the built environment, we have an opportunity to create a circular economy, where deconstruction feeds into a repair and refurbishment economy, and where new designs call for repurposed or refurbished materials that bring their previous stories and character to a new project. Instead of a material's “end of life,” we should talk about its “end of use,” since a circular product may be reincorporated into many buildings over many years.

Defining a circular economy

Materials in a circular economy are recyclable or compostable. Solid materials, such as many metals and unfinished wood, can be reused, recycled or composted. Most plastics are not recycled, despite labeling that encourages it. In addition, materials should be free from toxins, as these make recycling and composting difficult and hazardous.

Circular economy products are not glued together, are durable and repairable, and contain few toxins. Can the light fixture housing accept a new LED in 10 years? Can the new desk easily accept a new finish? What is the success rate of a carpet tile’s takeback and reuse program? Do the wood wall panels have hidden fasteners? Are glues used to attach this product or hold it together? Composite materials adhered with glues often need to be landfilled—they cannot be separated—along with products with thin, nonrepairable finishes.

Circular economy buildings are durable, long-lasting and flexible. When part of a building can no longer serve its purpose, it can be disassembled to provide used products for refurbishment and return to the circular economy. How do we measure success of the circular economy? While waste diversion rate is a common yardstick, it includes incineration, downcycling and other practices that don’t return a product’s embodied carbon to the economy as a product of equal value. Instead, we should measure how much demolition is avoided or is transferred to the circular economy, retaining its carbon value.

Two people talk at a reception desk, with materials choices reflected in desk, ceiling, flooring and lobby furniture. — The Hines Seattle headquarters retained and reused materials, as well as making use of salvage. Image credit: Benjamin Benschneider.

A shift in perspective

Practically, how do we apply these principles? First, we must make a shift in thinking and design rigor: Can existing walls, floors and ceilings be seen as assets? Could a new color palette, design idea or creative reuse tactic retain most of what exists already? During demolition, what products can be exported to the circular economy? What still has value after the first use? What circular economy marketplaces exist with products that could be specified to displace the need for new products and provide a project story?

Case study: Hines Seattle

This shift in thinking led the design rationale for a tenant improvement for the Hines Seattle headquarters that LMN Architects completed, resulting in a significant reduction in embodied carbon. While a design with best-in-class new products would reach a 22% embodied carbon reduction (compared to a typical remodel that begins with an empty shell), a 65% reduction was made possible through creatively retaining materials in place or elsewhere on-site, using salvaged materials, and buying a small number of new, low-carbon materials. View larger PDF version of graphic.

A few highlights:

Carpet that was initially suggested to be discarded was brought into the material palette, with other colors added to be sympathetic, such as new accent tiles.
New, unused but destined-for-landfill carpet was found and procured for the lobby space.
Existing, unneeded acoustic insulation was bagged for off-site use in rebuilding flooded homes.
Open office space was designed to be open to structure, eliminating the need for a ceiling.
An existing large glass relite was close in size to a new pane needed, so it was relocated within the space.
The feature wall used thin wood offcuts that were destined for incineration, assembled into a striking design using our shop and parametric software.

How to get started

Your current project can help kick-start the circular economy in your area:

Design with at least one salvaged material on every project.
Look for sources of excess material at salvage retailers and distributors' warehouses, or in attic stock.
Design for disassembly: this means using screws, hidden fasteners, durable materials with repairable finishes and those that can be taken apart to be recycled.
Consider reducing attic stock (overage) requirements for new projects—how much is really needed?
Engage a demolition expert who understands salvage. Many cities have such experts.

Three colleagues in a meeting room, showing the ceiling, window and table designs, with another colleague shown in an adjacent room. — The Hines Seattle headquarters was estimated to have a 65% carbon reduction through its strategies. Image credit: Benjamin Benschneider.

What to look out for

Some pitfalls you may encounter as you move toward a more circular approach to your projects:

Designers rarely assess existing assets creatively, starting instead by thinking of each space as an empty shell, even when assets remain. Relying on new products, even when refurbished products exist, is important for the whole team to question.
Scheduling a quick demolition phase can end up causing products with remaining useful life to be sent to landfill.
A “restoration” clause requires tenants, before they leave, to remove walls, furniture and everything else they’ve installed. This often sends relatively new products to the landfill, even if the next tenant may have wanted the economic and carbon advantages of reusing some assets.
Relying on “waste diversion” for demolition success metrics doesn’t capture the full picture.

The circular economy is a critical climate change reduction strategy, requiring collaboration within the whole AEC industry to get off the ground. Every project, large or small, can contribute to this movement through deconstruction and by specifying salvaged products.

Toward a circular economy of building materials