This course is part of the Concrete Academy

Outside the United States, municipal and national governments are taking the lead in pushing for the greater use of recycled material in architecture and design. Take Switzerland, where the government has mandated that a quarter of the aggregate in concrete must be demolition waste for it to be considered recycled. The city of Zurich is incorporating reused materials in all of their new public buildings, such as the David Chipper­field Architects–designed extension to the Kunsthaus Zurich, opened in Fall 2021 ­(RECORD, December 2021). Nearly all of the museums’s concrete contains at least 25 percent recycled aggregate, with some parts utilizing as much as 50 percent.

In Oslo, similar ambitions are being rolled out in projects such as the Mad Arkitekter–designed KA13. The 46,000-square-foot office-building renovation and expansion, completed in 2021, is Norway’s first project to incorporate circular solutions at a large scale, with an estimated 80 percent of building materials being recycled, including reused windows, facade tiles, and hollow-core concrete slabs, among other items. For the design team, one of the great challenges was locating reused building materials in the absence of a comprehensive marketplace for buying and selling such components. To solve that quandary, Mad Arkitekter created its own network to source those materials from more than 25 different sites. The project was also designed to be disassembled by, for example, bolting rather than welding steel structural elements.

Photos courtesy of KYRRE SUNDAL

EIGHTY PERCENT of the materials in the 46,000-square-foot expansion and renovation project KA13 (top), in Oslo, are recycled, including facade tiles (bottom).

And, in London, mayor Sadiq Khan recently published a set of planning guidelines that require new developments to produce whole-life-cycle carbon and circular-economy statements that must demonstrate how a new development will adopt strategies to aid the transition to a circular built environment, provide numerical targets for the monitoring of waste and recycling, and lay out opportunities to save resources and materials.

While firms can embed a circular approach into their design practices and develop protocols and tools to support that effort, there is also an emerging set of software providers working in this area. Take Concular, for example—a Berlin-based software platform that allows practitioners to digitize materials for both new and existing buildings and, with the help of AI technology, measure their embodied carbon. The platform also serves as a marketplace connecting would-be buyers with building materials. The software can be used via smartphone and 3D scans and, in a matter of hours or days, can create an appraised inventory of building materials and pair them with open orders for new buildings or manufacturers. “Today, we do not know what materials are in a building when the deconstruction process begins, and that limited time frame hinders the possibilities of material reuse,” says Con­c­ular cofounder Dominik Campanella. “To avoid this bottleneck, we systemically map the materials of a building at least a year before deconstruction. This allows the demolition team to know what materials must be removed selectively and either reused or recycled.”

The software has been successfully implemented across Germany. At the Mercedes-Benz Arena in Stuttgart, Concular digitized the materials within the approximately 110,000-square-foot main stage and VIP area ahead of the scheduled refurbishment for the 2024 Euro Cup. Existing materials, such as 3,000 seats, were sold off to manufacturers and fans of the local football community. And, in Berlin, the David Chipperfield Architects–led reconstruction of the Karstadt Hermannplatz department store will rely on the software to source certain materials, including recycled natural stone.

Photos courtesy of THOMAS JONES

AHEAD OF THE renovation of the Mercedes-Benz Stadium in Stuttgart for the 2024 Euro Cup, components were catalogued with the help of the digital platform, Concular.

Toxnot, a software company based in Colorado, is similarly attempting to simplify the notoriously complex global supply chain. The platform maintains a database of approximately 120,000 chemical substances and tracks 20 hazard end point ratings for all of them, such as carcinogens, endocrine disruptors, skin irritants, flammability, and environmental persistence, explains Mason Wambolt, director of business development. “So, a manufacturer can put a formulation for a specific material into the Toxnot system, and it will reveal those hazards.” Identifying toxins prior to specification increases the likelihood that materials will be repurposed.

The shift toward a more circular economy is an imperative step in reducing global greenhouse emissions and environmental pollution. That will entail preserving existing buildings, where possible, for adaptive reuse (to avoid waste associated with new construction), and the recycling of existing materials. There are plenty of obstacles to achieving such goals, but, with the proper specification protocols and material-tracking tools—and enlightened clients—firms can establish internal frameworks to plug themselves into the circular economy.

Supplemental Materials:

A Circular Economy for Buildings: Arup
Ellen MacArthur Foundation

Matthew Marani, writes about architecture and urban design and is studying city and regional planning at Pratt Institute.