To view the figures and tables associated with this article, please refer to the flipbook above.
- As much as 75% of typical emissions associated with the construction of a building could be avoided with a single key principle: circular construction. These include activities such as:
- Material reuse: Sourcing components onsite or offsite from an existing construction for use in a new project.
- Adaptive reuse: Adapting an existing construction for a new use retaining existing elements.
- Deconstruction: Careful disassembly of the components of an existing construction for direct reuse in other projects with minimal processing as opposed to demolition and sending all material to landfill.
- Design for deconstruction: Ensuring that materials and assemblies can be readily disassembled and reused at the end of their service life.Design for adaptability: Ensuring that the construction can be readily adapted to different uses (e.g., commercial, residential, office) and loading conditions.
- Choosing recyclable and reusable products: Prioritizing the procurement of materials and construction products that are recyclable and reusable.
Circular construction can reduce pollution, minimize waste, and conserve more resources compared to the status quo. The unfortunate reality is that the current state of construction is not yet suitable for implementing circular strategies efficiently or economically. The construction sector operates in a highly linear fashion resulting in a system that often leads to excessive consumption, and as a result, greater pollution and waste. This further limits the availability of information on how circular economy principles are implemented in practice when example projects are few and far between.
Promisingly, numerous efforts are underway to shift the market towards a more circular model including digital reuse marketplaces (e.g., Rheaply, Cambium Carbon, Lifecycle Building Center), local deconstruction specialists (e.g., Re:Purpose Savannah, Vema Deconstruction, Urban Machine, RE-USE consulting), and national and regional networking hubs (e.g., BuildReuse, All For Reuse, Valley of the Sun Deconstruction and Reuse Working Group).
SEI’s Sustainability Committee recently launched a database featuring successful circular construction case studies involving structural components. This database provides structural engineers with reference-built examples demonstrating the successful implementation of circular construction principles. Engineers can readily learn about common strategies, challenges, and lessons learned alongside important aspects like cost and carbon impact.
A Database for Structural Engineers
The free SEI Circular Economy Case Studies database (bit.ly/SEI-CE-database) is a first step to accelerate the uptake of circular construction practices in the sector through education and knowledge sharing. With increasing implementation of circular strategies, engineers can help prime the supply chain and transform the market for circular construction to become the norm.
Specifically aimed at structural engineers, the database is focused on structural component reuse, design for disassembly, and project deconstruction and stockpiling. It is construction material agnostic but focused on components that are reused structurally. The database aims to include projects from around the world but has a particular focus on case studies in the U.S. and Canada. The database features both building and bridge case studies.
The primary goal is to provide successfully completed projects examples that engineers can use as support in their future projects. These examples include useful technical, commercial, construction, and permit stories that can provide confidence to a future project team that a circular economy approach is practicable and beneficial.
The three case studies here demonstrate the sustainability and economic benefits of a circular economy approach, and a roadmap for working within the expanding network of circular economy-focused local regulations.
Key Takeaways
- Circular economy practices can significantly reduce construction-related emissions and in some cases reduce project costs.
- This database provides key insights into timeline, cost, and design implications from the application of circular construction principles to set project teams up for success to pursue similar strategies.
- Engineers are encouraged to submit case studies to grow the library, share knowledge, and facilitate more successful circular construction projects and meaningfully transform the industry.
Case Study 1: Procurement Before Design: Not Your Conventional Project Timeline
K118 Kopfbau Halle (Winterthur, Switzerland) | Locally sourced salvaged steel beams were used to add three floors of office space to an old warehouse. An estimated 60% of greenhouse gas emissions savings was achieved compared to building with only new material. The characteristics of salvaged components heavily influenced the design and were sourced before the project officially started. The major cost drivers of reuse include the labor (dismantling, processing, and reassembling) and reuse expertise. Heavier and larger elements were found to be less economic to reuse compared to building new (e.g., foundations). Conversely, lightweight elements and those with complex manufacturing processes (e.g., windows) could achieve cost savings compared to new components.
Case Study 2: Cost Saving: How Reuse Can Save More Than 80% Compared to New Materials
Green Valley Road Bridge (Ohio, US) | An old bridge was replaced using steel members salvaged from a local bridge. There were specific requirements for the new bridge, including a minimum span and maximum depth. As such, verification of the load carrying capacity of the available steel members was important and accomplished with inspections and mock testing before being commissioned for installation. A key aspect was to source the beams before they are cut to shorter lengths so they can be resized to meet project requirements. This saved $51,000 compared to new material, a true win-win!
Case Study 3: Deconstruction Ordinances: The Power of Regulation
Boulder Community Hospital (Colorado, US) | Over 500 steel members were deconstructed from a community hospital and stockpiled for structural reuse. The deconstruction of the hospital diverted about 94% of material from landfill. Motivated by Deconstruction Ordinance 8366, the project team aimed to achieve 90% waste diversion. The steel stockpile is estimated to have carbon emissions savings of over 36 tons CO2e. However, the deconstruction exhibited additional labor and time costs amounting to about 20% higher costs than typical demolition. The commitment of the design and construction teams was necessary to meet the diversion requirements. The project demonstrated that structural component reuse at-scale is possible, though deconstruction and recovery costs will likely be a primary challenge for future projects.
Database Features
Projects in the database are listed in a simple table format where users can easily search and filter through all published case studies for specific project aspects like material, circular economy principle, and construction use (e.g., residential, office).
Each case study includes an overview of the project, the sustainability goals for the project, the circular economy strategies applied, key findings, lessons learned, and links to further information and resources. Quantitative information such as cost and carbon metrics are included as they are available.
Submitting a Case Study
Case study submissions are open to the general public. Design teams, developers, and all other interested parties are encouraged to submit new case studies to the library and can do so by using a simple submission form (bit.ly/SEI-CE-submit) which can also be found on the Case Studies webpage.
By growing the circular economy case studies library, design teams are better equipped with knowledge from built examples going into projects pursuing circular construction strategies. With a larger collection of case studies, the profession can gain visibility into patterns of successes and pitfalls that can inform industry-wide action and influence transformative policies. ■
About the Authors
Dan Bergsagel is the international Sustainability Lead for schlaich bergermann partner (sbp) based in their NYC office and is a visiting scholar at Cornell AAP’s Circular Construction Lab. He chairs the Circular Economy Working Group for the ASCE Structural Engineering Institute Sustainability Committee.
Tracy Huynh is a senior associate in the Embodied Carbon team within the Carbon-Free Buildings Program. She leverages her expertise in structural engineering, mass timber construction, and life-cycle assessment analyses to support the team’s goals of reducing carbon embodied in building materials to meet rigorous climate targets.
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