Circular Design

Circular design is a framework that tackles global challenges including climate change, biodiversity loss, waste, and pollution. Design is an essential element of developing a circular economy that is restorative or regenerative by value and design.

The built environment sector is a major consumer of natural resources that have typically followed a linear progression from sourcing, use and disposal as waste. This take-make-use-dispose model creates negative impacts that include rising carbon emissions, increased pressures on landfill, unsustainable levels of water extraction and widespread ecosystem pollution. These negative externalities also include less tangible consequences on human and animal welfare, health, employment and social equality.

By fundamentally overhauling the processes, components and systems used to create the built environment, sustainable design embeds a system that designs in the elimination of waste and priority for efficiency.

Waste is a design failure

The premise of circularity as a concept is that waste is a design failure. This calls not only for a considerable, systems level prevention of waste generated by inadequate design, to construction phase and operations phase waste, and ultimately of end-of-life construction and demolition waste. It calls essentially for a fundamental design shift, whereby waste is designed out of the system and, whenever this isn’t possible, “waste” is reconsidered as “nutrient” and re-integrated into our material cycles.

The Hannover Principles of chemist Michael Braungart and architect William McDonough developed in the context of the World Expo 2000 held in Hannover, identify the key elements of designing the built environment to consider not only in terms of environmental impact, but to extend the scope to consider the effect on sustainable growth and society.

The built environment has a growing impact

The engineering and construction industry is the world’s largest consumer of raw materials and has consumed over 3 billion tonnes of raw materials. Global population growth and lifestyle changes are increasing the demand for these resources, many of which are becoming scarcer and harder to extract – placing unprecedented pressure on natural resources.

Competition for resources and disruptions to supply are already contributing to volatile materials prices, creating uncertainty in the short term and increasing costs overall. With the built environment under increasing pressure to minimise its impact, a circular approach could help the sector sustain our human-made habitat for current and future generations by enabling a healthy planet, thriving communities and viable economics.

Circular design strategies

Circularity-by-design requires us to evaluate design decisions through the impact they will have on the future. Designing for circularity means considering how buildings and infrastructure will perform not only throughout their planned utilization but also beyond. For most of the existing building stock, this long-term approach was not considered before construction, making decommissioned structures unfit for re-use or even, in some cases, for basic salvaging of building materials and components.

Designing for circularly means foremost deploying design for longevity. Several specific design strategies are possible, including designing robustly, meaning for increased wear and tear resistance, but also designing for ease of disassembly, for ease of repair and maintenance, for flexibility, and maximum performance. Considering that building elements have different lifespans, it is a daunting task for designers, which requires out-of-the-box thinking and innovation.

Regenerative design – beyond “doing less harm”

Beyond the framework of minimizing negative environmental impacts, regenerative architecture extends the paradigm of sustainability in which negative impacts are eliminated and buildings become part of the environment. In the context of construction, regenerative design aims to restore, renew, or revitalize the sources of energy and materials used to create and operate the built environment. Regenerative design uses whole systems thinking to create resilient and equitable systems that integrate the needs of society with the integrity of nature.

By rethinking how we use our cities and buildings, there is an opportunity to address global challenges – not just around materials and the circular economy, but also around our environment, our green spaces, and how we infill between major infrastructure. Regenerative design for sustainable development is the future and offers the keys both to a thriving economy and to a healthy environment we can all enjoy.

The road to regenerative urban development begins with a switch in our thinking, so that by-products conventionally considered as ‘waste’ can be re-framed and reused as resource inputs. Regenerative cities are productive centres that help to regenerate the materials and resources they use and foster a mutually beneficial relationship between urban areas and their surrounding territories. Considering that 70 percent of the world population will live in cities by 2050, this is the only way we can continue to prosper and thrive within our urban environment.

Reducing the material footprint

Reducing the material footprint by using less material or using materials in a more efficient manner is another winning strategy to reduce their carbon footprint coefficient and aim for better circularity. “Use materials in the way they want to work”, says Professor Philippe Block in an interview to L’Architecture d’Aujourd’hui, June 2021. Advanced computational design techniques allow for less use of materials as proved by Philippe Block in the flagship NEST HiLo Unit at Dübendorf, Switzerland, where double curvature concrete vaults are built without the use of reinforced steel. Using materials for their full structural potential has the advantage of reducing the volume of materials required for a structure while also decreasing the embodied carbon coefficient of the materials used. Biomimicry, through emulation of natural forms, is a source of inspiration to use materials more effectively, such as Philippe Block’s shell inspired designs. Emulation of nature furthermore produces shapes with an appealing aesthetics.

Lifecycle thinking

Lifecyle thinking refers to the evaluation of environmental impacts of a material, product or building throughout its lifecycle, considering a cradle-to-grave cycle. Although its applications to circular economy are not essentially conductive to systemic change and must be weighted carefully, we recognize the role that life-cycle assessment (LCA) has in analyzing, measuring, and comparing carbon impact of alternative building materials and components, and thus driving better design and material supply decisions. Lifecycle thinking is influential when it comes to better embodied carbon choices.

Taking into consideration the main life cycle phases, we can best appreciate the carbon dense phases of a material or building process and enact design choices that counterbalance or eliminate these effects. When examining a material though the lense of material extraction, processing or manufacturing, packaging, transportation, construction, operations performance, and end of life, we could be more prone to use a local material, for instance, with very low transportation footprint. Or act upon our construction or operations processes for incremental efficiencies and improvements.

Circular economy (CE) and digital applications

Digitalization also plays an important role, enabling digital design and construction methods that optimize resource use and re-use, such as standardization, modularization and material passporting, while also assisting with an optimum, tailored supply of materials (BIM applications) and smart building technologies for predictive maintenance (IoT applications).

In the realm of circular digital applications, the concept of material passports is well researched in terms of opportunities and holistic implementation and is becoming widespread. The architect Thomas Rau and Sabine Oberhuber have pioneered the concept in their momentous book Material Matters. “Every building is a material depot” and “Waste is material without identity” are its quotes that have resonated with the circular built environment community since.

The building passport platform format has been in use for some time now, providing a digital library of building materials and a wealth of information for the whole construction value chain. Integrations with the platform allow managing design, construction, operations, maintenance, and end of life holistically.

Attributing identity to materials informs their performance potential during and beyond the end of use of the building and encourages manufacturers to more transparent materials declarations. The concept of material passporting is getting a strong hold since, with Triodos Bank building being the world’s first 100% demountable building, enabled by BIM-based building passporting. Material passports have the potential to be used for renovations as well, enabling a second and third life for old buildings.

Digital design and fabrication of material components are key innovative construction technologies under continuous exploration, allowing lean design, or a more frugal use of resources, and significantly reduction of energy and carbon footprints.

AI powered tools can be powerful enablers of building components upcycling. Unmaking Architecture, "Next Generation" 1st prize 2020 North America and Holcim Research in Practice Grant (RPG) recipient, combines an indexed library of demolition rubble, and computational tool to guide design of new buildings to optimize the use of available materials. “The entire library be matched like jigsaw puzzle pieces onto adjustable shapes, producing significant money savings as well as a reduced carbon footprint for building construction”.

Build less and for sufficiency

The most effective means to reducing the carbon impact of the industry, is to limit the use of materials and resources for building. Frugal design and sufficiency are paths that should be explored by practitioners, as well as building less. “Growth in floor area: the blind spot in cutting carbon” remains largely unquestioned in regions of the world conflicted by high urban density and an aging housing stock. In Europe, for instance, a staggering 35% of the building stock is over 50 years old, resting the case for building retrofit, and in general upgrade of building energy performance. Material stock reuse is potentially compromised, as most of these buildings have not been designed with circularity and disassembly in mind.

Strategies as retrofitting, adaptive reuse, newly designed spaces, and infrastructures with multifunctional capabilities, but also co-housing solutions, all lead to less construction for both the residential and commercial sectors. Initiatives like AJ’s RETROFIRST are actively advocating for retrofit against demolition.

The ultimate solution is to build nothing. “If less is more, maybe nothing is everything”, says architect Rem Koolhaas. This is epitomized in Anne Lacaton & Jean-Philippe Vassal project for a public square in Bordeaux. When the architects were asked for a proposal for Place Léon Aucoc in Bordeaux (1996), they determined that the existing park was successful, and nothing needed to change.

In other regions of the world, country-specific challenges of implementing circularity can be substantially very different. Typical urban sprawl issues, increasing housing needs and dramatically reduced climate resilience dictate different CE applications, case by case. Building for adaptability, for multi-functional uses and for disassembly remain are all effective strategies that should be pursued. Models for co-habitation dramatically decrease the need for residential space, as well as producing social benefits that meet the needs of today’s evolving demographic needs.