Ever since the industrial revolution, the global economic system has been based on a single linear pattern: the “take – make – throw” model. Companies manufacture products using harvested or extracted materials and consequently sell them to consumers who – once the products are broken, old, or out of fashion – dispose of them, including all their embedded raw materials, water, energy, and knowledge.

To break this pattern, there must be a paradigm shift in the underlying approach, one that will radically change our economic and ecological understanding and decouple economic growth and resource consumption: a shift from a linear to a circular economy.

By Felix Heisel

This transition offers potential material savings worth more than one trillion dollars. Within the circular economy, material resources are used continuously in either biological or technical metabolisms at their highest value and utility, without ever turning into waste. In combination with new business models that separate performance and hardware, this allows manufacturers to retain ownership of their resources, leading to an increased security in stock management for production.

Most importantly, the circular economy is not an end-of-pipe solution but a new economic model with a design imperative: when the product itself is the raw material for the next creation, it makes sense to design for disassembly into pure-type raw-material cycles; and when companies only sell services and lease products, it makes sense to design products that are compatible, long lasting, and easy to repair.

The concept of cycles thus plays a fundamental role. In general, the smaller the loop the more efficient it is in terms of energy and resource input. Ideally, with respect to the sought-after paradigm shift, materials, components, or products should never fall into the scope of waste legislation. Various concepts, such as design for disassembly, product as service, or extended producer liability, aim to prevent the intention, need, or interest in discarding substances or objects by ensuring their utility and value within a closed-loop application. Yet the construction of cities for deconstruction in the form of a material depot has hardly begun.

Construction for deconstruction – tucked, folded and glued

To test the viability of the circular concept, in 2018 Werner Sobek, Dirk Hebel, and I built a full-scale experiment at the Swiss Federal Laboratories for Materials Science & Technology (Empa) NEST research building in Dübendorf near Zurich. The Urban Mining and Recycling (UMAR) unit is underpinned by the concept that all the resources required to construct a building must be fully reusable, recyclable, or compostable. In its investigation, UMAR addresses a wide range of scales and topics, such as alternative building materials, circular construction methods, urban material cadasters, and new economic business models. The unit’s supporting structure and large parts of the facade consist of untreated timber; the portal frame of the facade is covered in repurposed copper sheets from the roof of an Austrian hotel. The interior of the unit contains an extremely diverse range of serially manufactured building products, whose various constituent materials can be separated and sorted before being introduced back into their respective materials cycles.

Among the technologies used are cultivated mycelium boards, recycled bricks, repurposed insulation materials, and reused door levers. The greatest innovation lies in the connections, which can all be easily reversed because materials are tucked, folded, or screwed rather than glued. Consequently, pure type-sorted recycling or pure biological composting of all elements is feasible at the end of the unit’s use time.

Most building legislation makes no distinction between material use cycles. For example, in Germany reused or recycled products or materials must comply with the standards of DIN or EN norms with respect to structural, fire, health, or other specifications – like any virgin resource. This is both an opportunity and a limitation: On the one hand, if a material’s certification exists, there is no reason to not use reused or recycled resources. The problem is that most of the time no such certification exists for reused elements. Missing documentation about origin as well as treatment during use phases makes this step particularly difficult.

Making circular construction feasible

The Mehr.WERT.Pavillon by KIT Karlsruhe and the office 2hs, located on the premises of the 2019 Federal Garden Show in Heilbronn, aims to prove that the urban mine provides high-quality material resources for structural applications. Next to recycled glass, plastics, and mineral demolition waste, the pavilion’s structure is made from reused steel that was reclaimed from a disused coal power plant near Dortmund. In addition to a detailed visual inspection to determine possible damage to the elements, the steel was tested at KIT laboratories for tensile strength, elasticity, notched bar impact strength, and chemical composition — enabling the reuse of this sixty-year-old steel in a structural application. This example clearly demonstrates the feasibility of circular construction, and it also highlights the important steps that still need to be made in terms of material quality, selection, and documentation.

Re-materializing Construction

This text is extracted from the paper Reuse and recycling: Materializing a circular construction presented by Felix Heisel at the LafargeHolcim Forum for Sustainable Construction on “Re-materializing Construction” held at the American University in Cairo, Egypt. The full text is available as a flip-book via the link below:

Reuse and recycling: Materializing a circular construction

Inspired by the discussions by 350 leading thinkers from architecture, engineering, planning, and the construction industry from 55 countries, Ruby Press Berlin has published The Materials Book that evaluates current architectural practices and models, and introduces materials and methods to maximize the environmental, social, and economic performance of the built environment in the context of “Re-materializing Construction”.

The Materials Book: Re-materializing Construction – Cairo (Ruby Press)