As people around the world increasingly question our impact on and relationship to the physical environment, so too should those who design how we live and work within it. With thoughtful planning, collective efforts and careful attention to the life cycle of materials, sustainability in the A/E/C industry could be closer than we think.

Close the loop. Circular cities, buildings, clothes, food. Re-something. Something-cycle. Salvaged barns, shoes made from plastic bottles, no more seabirds stuck with caps in their stomachs. Even better, make it from crop waste, completely compostable, biodegradable. And what about mushrooms?

Now, back to your excel sheet, BIM model, contract, or phone call with this flavor in your mouth. It’s not as bitter as the news about how warm these years have recently been or the current loss of biological species. It has some futuristic taste to it — yes, an optimistic one. Good ideas you will talk about in that meeting, everybody will get what a circle is. And then? Maybe we can put that in next year’s sustainability goals …

Why does the circular economy feel beyond reach? For two fundamental reasons. First, it requires us to consider the very aspects we have kept out of sight: the extraction of resources, the production of goods and the accumulation of waste. This is driven by the second, larger reason: the circular economy requires a systemic transformation of our whole economy, which is based on the opposed linear take-make-waste approach.

So how can we make this transition happen? Like any overwhelming task: break it down, understand what it is all about, convince ourselves it is the right way to go, and proceed with strategic and collective steps.

Not just circling for the sake of circling
To put it simply, the circular economy is a framework where materials are perpetually kept in use to achieve three goals: minimizing extraction of finite natural resources, eliminating waste, and minimizing or even turning negative environmental and health impacts into positive ones — in short, make the material aspects of our lives sustainable.1

Keeping materials in use means preserving the maximum value of each thing that has been produced for the longest time possible. Reuse it as long as you can (give it to another user or share it). Repair it if you can’t reuse it as is. Or, if it has too little value, then remanufacture it (turn it back into something with an as-new condition). At worst, break it down and recycle each material (or compost it) for another future use.

Business opportunity today, risk tomorrow
The powerful aspect of this framework is that it focuses on value; it is not just a circular moral imperative that can be eluded, as the one for sustainability sadly still is. It is a new economy — for the 21st century. From the World Economic Forum to consulting behemoths like Accenture or McKinsey, by way of global companies like Caterpillar or Ikea, many stakeholders are understanding why the circular economy can make great business sense today and future-proof their growth.2

Raw materials are finite and facing ever-rising pressure due to the increase in the world’s population and the strengthening purchasing power of a number of countries — their prices will very likely rise and be more volatile.

At the other end of the production process, people — citizens, customers, investors, communities, governments — feel the urge to act and behave more responsibly towards their environment, becoming increasingly aware of the burden of industrial activity, but also of waste.

Maximizing the use of things can also be an opportunity to intensify manufacturers’ relationships with their consumers. For instance, Philips Lighting, the world’s largest lighting manufacturer, offers “Circular Lighting” as a professional service. Users, such as Amsterdam’s Schiphol International Airport, pay only for the light that is used rather than purchasing their own lighting equipment. Philips owns the equipment and takes care of the operation, the maintenance, all future technology updates and the end-of-life management.3

What about the building industry? It is growing and will only continue to expand with cities and population growth. It encompasses a very large array of different things, from concrete to carpets, by way of air ducts and elevators. So far it overlooks the impact of materials — roughly 10% of global carbon emissions4 — concentrating often exclusively on energy-efficiency. And it deals with many finite materials while wasting enormous quantities of them.

The circular cities of tomorrow
Let’s imagine: In a circular building industry, deconstruction would be the norm and as minimal as possible. Unused materials and components would not impede any landfill. Rather, they would enter a vast market ranging from salvaged components to recycled and renewable materials. Any hazardous or harmful material would have been phased out. New products would be made to last: easily repairable and upgraded, remanufactured, and eventually recycled or composted. Buildings would be assembled to allow each of their parts to smoothly enter the circle again.

Spaces would be flexible, used and occupied intensely. At any time of the building’s life, one could know the state of its components and so plan for timely maintenance. Parts of the building, like the structure, would be owned for long periods of time. Others (partitions, furniture, carpet tiles, curtain wall façade modules5) would be leased and upgraded according to the user’s needs. Each owner would consider his property as being a profitable material-bank.

To accelerate the transition towards such a future, there are already attitude-shifts and actions that can be carried out today. Owners have good reasons to make upfront choices improving the circularity of their projects. Designers, whether architects or engineers, can design and specify differently — often with minimal impact on the project budget — and advocate for change. Manufacturers and builders have an opportunity to cut on materials, construction and waste-management costs, while securing a strong position in the market. Each stakeholder should build up a strategy to capture the value of materials and components that the circular economy enables them to retain.

Good for the bottom line
Admittedly, because the linear model of production is the dominant one, it seems likely that any deviation from it would increase risk and costs. However, because of the complexity of real estate developments and the nature of the circular economy (which looks at previously unexplored value), there are situations where this common sense can be proven wrong.

Construction costs can be reduced by making the most of what exists on site — buildings, structure, spaces and materials. When preserving is not an option, donating building components coming from deconstruction to non-profit re-use centers can result in significant tax deductions on top of avoided landfill fees. Meanwhile, Materials and Resources LEED credits can be earned.

Deconstruction has many benefits, especially for refurbishments such as façade upgrades or interior commercial remodeling. In the 101 East Erie Street office conversion project in Chicago, for example, deconstructing 220,000 square feet of ceiling tiles to be recycled by the manufacturer saved three weeks in trade coordination.6

Deconstruction can also be a tool for community outreach. In urban areas, deconstruction drastically reduces noise and dust. It can also be a way to invite the community to participate in the transformation of the urban fabric, either by training the local workforce in deconstruction or by involving the community in the strategies for the reuse of materials. The prolific work of Theaster Gates7 or Rural Studio8 could serve as inspiring examples.

Finally, a circular building allows for a swifter maintenance, as well as efficient modifications to space layout, systems and envelope.

Design for circularity — materials and components
For designers, the very first step is to inform any material choice by an idea of what happens before, during and after its use. Based on this knowledge, prioritize existing and salvaged materials over repaired or remanufactured ones, remanufactured over recycled or bio-based ones, and recycled over those made with virgin materials.9

Take wood: Reusing a wood component increases its capacity to store carbon,10 as its end-of-life (when the carbon is released) is postponed. This reuse can take many shapes. In Georgia Tech’s Kendeda Building, for instance, nail-laminated floor decks smartly incorporate salvaged wood boards sourced from a local re-use center to act as non-structural spacers between virgin boards.11

For structural steel components, recycling is by far more common with an 85% recycle rate,12 which can in return be required in the specifications. In contrast, concrete, when not reused, is most often down-cycled and used as road base or construction fill. Its impact can be mitigated, though, by reducing the embodied carbon.13

Façade glass is also down-cycled, crushed, and used in aggregates in road construction, if it does not end up in a landfill. Instead, it could at least be recycled, as the Verde SW1 project in London led by Tishman Speyer and Arup shows.14

Inside the building, manufacturers of carpet tiles and suspended ceilings very often offer more or less virtuous take-back programs, which are easy to specify and implement. Partition walls, changing along with space needs, could greatly benefit from being circular. And yet, despite the performant design of modular office walls, they are not managed in a circular way.15 They also can’t compete with drywall partitions, which suffer from contamination — especially from paint — resulting in low rates of gypsum recycling.

Overall, beyond informational Environmental Product Declarations (EPD), certifications such as Cradle to Cradle or Living Product Challenge can help guide the designer’s choice. Attention should be paid to the certification level, as the Cradle to Cradle label alone, for example, provides no guarantee that the products are not actually still cradle-to-grave.

One last principle: Keep it simple. However banal or generic this may sound, it helps ensure components will ultimately be recycled. This entails avoiding composite materials, privileging low-tech — if not passive — systems, minimizing finishes and coatings, and limiting the overall number of different materials.

Design for circularity — assembly
How the building is put together matters just as much. Buildings should be designed for disassembly to allow cost-effective reuse, repair, upgrade, remanufacture and recycling of their parts.16 At a large scale, the different layers composing the building should be easy to separate and not hopelessly entangled: the structure, the skin, the services (MEP and others), the space (partitions, floors, ceilings), and the stuff (lighting fixtures, furniture, ICT).17

Any connection should be reversible and accessible, not jeopardizing the reusability of its components. For steel, this means minimizing welded connections and using bolted ones or clamping profiles together, like the Lindapter products or the ConXtech system. Current binders used in wet trades, such as cement-based mortar, constitute an obstacle to reversibility.

Finally, materials and components should be appropriately marked to avoid unnecessary down-cycling or disposal, as with a glue-laminated wood beam, for example.

Towards a full circle
The circular economy is more resistant to, but not immune from, the usual pitfall: Whereas resource efficiency and eliminating waste are likely to be embraced by businesses in the near future (since they closely relate to economic value), there is the risk that the rest of the environmental and health impacts will be overlooked. Upon further consideration, the definition of the circular economy itself includes this flaw: Circulating things and designing them to circulate does not directly address the reduction of their footprint or their regenerative capacity.18 This is why each circular initiative should be valued by its success in tackling all three goals: minimizing resource use, waste production, and health and environmental impact.

That being said, even if the circular economy is not the holistic solution to all our environmental problems, it is a very powerful framework. Implementing small changes immediately while raising awareness and commitment collectively will gradually lead to innovations in business models, materials and design, eventually reaching full circularity. Yet such a transition might not happen fast enough. Legislation is urgently needed to support it and foster significant change in the coming years.

1-The Ellen MacArthur Foundation provides a more thorough definition with three principles. Principle 1- Regenerate natural systems: Preserve and enhance natural capital by controlling finite stocks and balancing renewable resources flows. Principle 2- Keep products and materials in use: Optimize resource yields by circulating products, components and materials in use at the highest utility at all times in both technical and biological cycles. Principle 3-Design out waste and pollution: Foster system effectiveness by revealing and designing out negative externalities.
2-See for instance the research from Accenture: Peter Lacy, Jakob Rutqvist, “Waste to Wealth: The Circular Economy Advantage”, Palgrave Macmillan UK, 2015.
3- pdf
4-According to Architecture 2030, based on the UN Environment Report of2017 and EIA International Energy Outlook, building and material construction contribute to 11% of global CO2 Emissions. Building operations account for 28%.
5-This is actually a research project at the university TU Delft in the Netherlands
6-Case study ment ioned in Armstrong’s ceilings recycling program: https://
9-See the Carbon Smart Material Palette from Architecture 2030 for a detailed understanding of how to mitigate the impact of several building materials, especially in terms of carbon emissions.
10-The storage assumption is based on sustainable forestry. Beyond the balance of trees, such forestry is even more so important, as forests as a whole (including leaves, branches and soil) store much larger quantities of carbon as the wood products themselves.
12-According to the World Steel Association. The rate drops to 50% in the case of household use. When recycling special alloys, their value is often lost.
13-Reducing the carbon impact of concrete can be achieved at least in three ways, with little or no consequence on the project’s budget: using Portland-Limestone Cement instead of ordinary Portland cement; minimizing the cement content, either by design or by replacing it partly with safe components like fly ash; or leveraging the natural carbon sequestration of concrete by using technologies like Carboncure at the construction stage.
14-In collaboration with British Glass. See also Arup’s report about construction flat-glass recycling available online: Arup, Graeme DeBrincat, Eva Babic, “Re-thinking the life-cycle of architectural glass”.
15-Some companies like Steelcase are researching the concept.
16-For detailed strategies for Design for Disassembly, see B. Guy, G. Ciarimboli, “Design for Disassembly in the built environment: a guide to closedloop design and building”, prepared for King County, WA., available online.
17-To use the concept of building layers from Stuart Brand.
18-Some ‘circular’ initiatives can have an overall negative impact as repairing, remanufacturing, and recycling can be transportation, energy and water-intensive processes. Opening undiscovered markets could in some cases lead to more pollution.

Joël Onorato is an architect and structural engineer, working at Hickok Cole Architects in Washington, D.C., where he is leading a research project on the circular economy. Previously, he was working in Paris, France, on bridge design, mixed-use projects and urban design, while researching the theory of digital architecture.