How the Circular Economy Can Transform Buildings Into 'Material Banks'

Demolishing a building with a carefully planned implosion is a spectacular sight, but the debris typically goes to waste in landfills. A new approach takes all that careful planning and puts it to work in a circular economy model that cuts carbon emissions, conserves resources, and provides for bottom-line benefits, too.

Recycling is a good start…

Recycling and reuse is one pillar of the circular economy that can be applied when a building is renovated or demolished. One early, ambitious example of that strategy is an energy-efficiency makeover for the iconic Empire State Building in New York City that included replacement of all 6,154 windows. Instead of demolishing the old windows as scrap, the contractor upcycled them. Each window was retrofitted in a workshop on site, which reused 97 percent of the materials.  

The renovation was completed in 2010, but savings from the overall 38 percent cut in energy use continue to this day. In addition, the window upcycling project saved $15.5 million compared to the cost of new windows.

…but much more needs to be done.

While energy-efficiency upgrades and the repurposing of building materials are now fairly commonplace, much more needs to be done in the coming years to accelerate the construction sector's shift toward a circular economy.

Buildings already contribute about 40 percent of global greenhouse gas emissions, a figure set to grow amidst population growth and urbanization. The United Nations Environmental Program is among those warning that growth in the buildings sector will outpace the efforts of recycling and other carbon-reducing measures.

“Raw resource use is predicted to double by 2060 — with steel, concrete and cement already major contributors to greenhouse gas emissions,” the U.N. Environmental Program warns, referring to an expected doubling of floor space globally by 2060.

One solution is to scale recycling up into a mainstream practice in the buildings industry. In 2019, for example, the World Green Building Council introduced a suite of recycling transparency and accountability recommendations under the title, “Bringing embodied carbon up front.”

To draw more attention to recycling, the World Economic Forum will give out a new “Circularity Lighthouse in the Built Environment” award at its annual meeting in Davos, Switzerland, in partnership with McKinsey & Co.

The Swiss green building firm Holcim is the first to receive the Circularity Lighthouse award for its EcoCycle recycling system. The process enables up to 100 percent recycled material to be used in concrete, cement and aggregates, with no loss of performance.

The company claims its EcoCycle technology "can recycle up to 100 percent of construction demolition materials across a broad range of applications, from decarbonized raw materials in low-carbon cement formulation, to recycled aggregates in circular concrete.” 

The Circularity Lighthouse award recognizes impact as well as innovation, and Holcim fits the bill. The company recycled almost 7 million tons of construction demolition materials in 2022 through its global network of 100 EcoCycle facilities. It plans to expand with another 50 facilities by 2030.

Beyond recycling: The concept of a "material bank" for a more circular economy in the construction sector

Although the expected doubling of global floor space by 2060 presents a significant challenge, it also presents new opportunities for rethinking the way that buildings are planned from the ground up.

The Ellen MacArthur Foundation is among those advocating for a new approach in which buildings are treated as repositories for materials that can reused.

The “material bank” approach is already suggested by the many historic sites and working neighborhoods around the world, where the original building materials have been in continual use for hundreds of years.

“The materials that are used for construction have the potential to be very long lasting, evidenced by the countless historic buildings that make up our cultural landscape,” said Nick Jeffries, an expert who works with the Foundation’s insights and analysis team.

The problem is that modern buildings are designed to be demolished, not disassembled. The material bank concept represents a new approach for a more circular economy. It incorporates design and construction strategies that enable more materials to be recovered intact and reused.

Jeffries provides the example of a community in the Netherlands that constructed a new “Lego-like” town hall. The building may not be needed in about 20 years, in which case it can be dismantled and the components can be reused.

“To achieve this ambitious reuse rate, irreversible concrete was avoided, favoring instead high-quality prefabricated timber elements, with design tweaks introduced by the supplier, allowing for maximization of future reuse,” Jeffries noted.

Jeffries also described a variation on that theme in Boston, where planners at a conference center anticipated that mass transit would eventually reduce the need for on-site parking. In the meantime, their solution was to build a parking garage with removable ramps and other design elements that can facilitate a relatively quick, economical transition to office space or other uses.

Digital technology and the construction material passport of the future

One major obstacle to mainstreaming the material bank concept is the lack of consistent, accessible information on building materials across all construction industry stakeholders. A solution is emerging in that area as well, in the form of material passports.

Digital product passports for textiles are already planned for the European Union by 2030 to help stem the tide of waste in the textile industry. Likely in the form of a QR code or other scannable tag, the passport will pull together a range of information — from the product’s origins and composition to its sustainability, recyclability and more.

Establishing a similar system for the construction industry will be more complex, but work is already underway. In November, for example, the London-based environmental and engineering consultancy firm Waterman Group launched what it calls the “first standardized approach to materials passports,” in alignment with the EU’s Digital Product Passport initiative.

The digitized, software-enabled effort emphasizes disassembly over demolition in pursuit of a more circular economy. It also includes an online marketplace for reselling materials. 

“Materials passports play a pioneering role in advancing sustainability within the construction industry,” Waterman explained. “The data they contain will facilitate informed decision-making on efficient material reuse while resolving the ambiguity around specification, performance and warranties of used materials.”

It remains to be seen if Waterman’s solution becomes the industry standard as the firm envisions. An initial trial is already underway at a 12-story office building set to be constructed in London.

In the meantime, the case for incorporating more circularity into the building industry is growing. A new McKinsey report, for example, outlines the carbon abatement and economic benefits of scaling up the re-circulation of cement, concrete, steel, aluminum, plastics, glass and gypsum.   

“Circularity in cement has the potential to create the highest value pool across materials, with an estimated net value gain of $10 billion in 2030 and $122 billion in 2050,” McKinsey notes. 

Both McKinsey and the Ellen MacArthur Foundation also advocate for the construction industry to promote “lighthouse” projects that best exemplify a more sustainable, circular approach to building design and recycling.

A lighthouse is a rather bleak, isolated image to deploy, but if support from legislators and other policymakers can help accelerate the circular economy in the construction sector, entire communities will become lighthouses for a more sustainable future.