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Closing the Loop

Circularity and Embodied Carbon Reduction in Buildings

Alan Scott New

We still have significant work to do to reduce the operational carbon emissions of existing buildings and to design new buildings for net zero carbon, but the necessity of reducing embodied carbon over the life cycle of building materials is now well established as a parallel goal. While much of this focus has been on the initial extraction and manufacturing stages of a products life cycle, working toward a circular economy for the myriad of constituents that make up our buildings is the ultimate goal.

Circularity means abandoning the traditional cradle-to-grave or downcycling (successive recycling into lower value materials) approach, into one in which disassembly, reuse, or closed-loop recycling are the norm rather than the exception. This requires moving from a take-make-waste approach to materials, to one where the life of materials is extended, and where used materials recovered at the end of their useful lives are the primary feedstock for new materials.

More importantly than a narrow consideration of materials, circularity starts with changing the way we think about what we design and how we design it. To elevate the importance of this approach and engage the building industry, Arup, a global sustainable development firm, recently introduced the Circular Buildings Toolkit, in collaboration with the Ellen MacArthur Foundation. The toolkit outlines 10 overarching strategies for creating circular buildings and building materials, falling into four hierarchical principles, providing a useful guideline for architects, contractors, and product manufacturers. The principles of circularity in the toolkit include:

  1. Build nothing–Shifting the focus from new construction to retrofit and renovation of existing buildings
  2. Build for long-term value–Increasing building utilization, and designing for longevity, adaptability and disassembly
  3. Build efficiently–Refusing unnecessary components and increasing material efficiency
  4. Build with the right materials–Reducing the use of virgin and carbon intensive materials, and designing out hazardous materials

According to Ilana Judah, associate principal and Americas East resilience leader at Arup, “circularity is a mind shift, transforming the way we think about designing, constructing, and maintaining buildings. Arup’s Circular Buildings Toolkit is a key part of the industry’s circularity journey, intended to educate designers and builders, and to encourage deeper conversations with their clients.” The Toolkit proposes key performance indicators to measure progress on this journey toward circularity. As more building professionals ask manufacturers for products to help reach circularity goals, similar to the material transformations spurred by LEED, the market will respond.

The metal building industry provides an example for the transformative potential of circularity. In efforts to reduce embodied carbon and other environmental impacts, metal carries both burden and advantage. Traditional manufacturing of these materials is carbon intensive, creating significant greenhouse gas emission and other impacts in the mining and processing of raw materials and the manufacturing of final products, and additional impacts at the end of life when composite materials may limit recycling potential. At the same time, these materials are very durable, making resilient, long-lasting buildings, and they are easily recycled into like materials.

Relative to the Toolkit strategies, metal building lends itself to design for longevity due to its durability, as well as adaptability and disassembly as typical lightweight, componentized systems can be deconstructed, and reconstructed or recycled into new building components. The properties of metal building components can also support efficiently designed structures. Finally, while steel and aluminum are currently very carbon intensive, an increased focus on circularity could accelerate adoption of renewable energy use in production and improvements in material recovery systems to maximize recycled content and minimize to need for virgin ores. The expanding adoption of “buy clean” mandates by governments and the growing focus of architects and contractors on embodied carbon will give manufacturers who adopt circularity a competitive advantage.

Incentives are emerging along with mandates. For example, the Inflation Reduction Act, passed by Congress and signed into law in 2022, included $350 million allocated to assist key areas of the building industry (manufacturers, real estate developers, institutional procurement officials, and contractors) to measure, report, and most importantly reduce the greenhouse gas emissions tied to the production, use, and disposal of building materials. This investment will fund grants, the development of tools, and the provision of technical assistance. The U.S. Environmental Protection Agency (EPA) will develop and administer these programs and is currently seeking information from affected industries to help shape the outcome. The initial focus will be on steel, concrete, asphalt and glass, with the second phase expected to include aluminum, gypsum board, insulation and roofing materials.

Powering industry with renewable energy will be a big part of this effort. A recent blog post by Christian Tae of the National Resources Defense Council (NRDC) highlights a unique opportunity for low-impact metal production in the U.S. He points out specifically that the Midwest is the U.S. region with the greatest potential for renewable hydrogen production from both solar and wind energy, and it is also home to much of this country’s industrial base, including raw steel production and metal product manufacturing. This sets up a near-perfect condition for renewable hydrogen to power low-emission metal building production.

While there are barriers to the dispersed distribution of hydrogen and in its use as a transportation fuel, it can be practical and economical if used in proximity to where it is produced. Renewable hydrogen electrolyzing can take full advantage of midday peaks in solar production when available solar energy significantly exceeds demand, and the abundant wind in the middle of the night when other energy demands are low. That hydrogen can then be used in place of coke as a reductant in steel production, and stored hydrogen can be used to produce clean energy to supplement directly supplied renewable electricity to fuel electric arc furnaces.

Complacency, inertia and economic barriers may have prevented the adoption of circularity in the building industry in the past, but new incentives, increasing consumer demands, emerging economic advantages, and the growing imperative to address the climate crisis are knocking down the old barriers. Building owners and developers, architects, engineers, contractors and material manufacturers all have a role to play in closing the loop in our built environment.

Alan Scott, FAIA, LEED Fellow, LEED AP BD+C, O+M, WELL AP, CEM, is an architect and consultant with over 35 years of experience in sustainable building design. He is Director of Sustainability with Intertek Building Science Solutions in Portland, Ore. To learn more, follow Scott on LinkedIn at