The construction industry in Europe stands at a critical juncture, facing a unique combination of challenges and opportunities that shape its future. As one of the largest and most impactful sectors, construction plays a central role in developing the cities and infrastructure of tomorrow. 

However, its environmental impact is significant: the built environment, driven by construction activities and building use, is responsible for 40% of global CO2 emissions and 40% of global resource use. This makes it a major contributor to the transgression of several planetary boundaries, including Climate Change, Land-System Change, and Biosphere Integrity. 

This case study selection highlights circular practices in the reviewed projects based on the 9R circularity framework, which serves as a set of guiding principles for transforming conventional construction practices into more circular and sustainable ones.

Built Environment: the 9R Strategies

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Business case

Impact on the availability of resources as well as their effect on living organisms, ecosystems, and components of the environment.

Ecological Impact

Reduced use of virgin materials and/or an increase of the use of secondary and bio-based materials

Reduce Material Consumption (SDG12)

Producing building materials and providing services to create residential and non-residential infrastructure and real estate


Construction and Infrastructure

Producing building materials and finished and semi-finished building products for construction

Construction Materials and Products

While resources are in-use, maintain, repair and upgrade them to maximise their lifetime and give them a second life through take back strategies when applicable

Stretch the lifetime

Give products and parts another life after their end-of-use

Maximise lifetime of products after use

Extraction and reuse of parts from end-of-life products for use in new products

Part recovery

**Make cities and human settlements inclusive, safe, resilient and sustainable**

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The pandemic has caused major shifts in migration patterns, including huge movements of people in and out of urban areas. Furthermore, climate change and conflicts tend to have disproportionate impacts on cities. These factors mean that the world is far from achieving the goal of sustainable cities.  
In many developing countries, slum populations have been growing, putting at risk the target of adequate housing for all by 2030. Since 2015, the number of countries with national disaster risk reduction strategies has more than doubled. 

Cities are hubs for ideas, commerce, culture, science, productivity, and social, human and economic development. Urban planning, transport systems, water, sanitation, waste management, disaster risk reduction, access to information, education and capacity-building are all relevant issues to sustainable urban development.

This target entails multiple essential concepts such as disaster risk reduction (DRR) and sustainable transport.

To achieve SDG 11, efforts must focus on strengthening capacities for planning for urban development, improving access to public transportation, and enhancing waste management. 

Sources: [https://sdgs.un.org/goals/goal11](https://sdgs.un.org/goals/goal11)
[https://sdgs.un.org/topics/sustainable-cities-and-human-settlements](https://sdgs.un.org/topics/sustainable-cities-and-human-settlements)


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11. Sustainable cities and communities

Make cities and human settlements inclusive, safe, resilient and sustainable

Slow strategies aim to keep materials in use for as long as possible, for example through design for durability and repairability. A more circular economy is also a slower one: materials, components, and products—and even buildings and infrastructure—that we lock in stocks are made to last. This will lower material demand in the long run, in essence also serving to narrow resource flows.

Slow

 The strategies maximise their lifetime and give them a second life (e.g., take back strategies) when applicable.

🏢 Extending the lifespan of products and parts

Maintain, repair and upgrade resources while they are in-use.

The strategies usually require technical equipment and energy inputs to create a new value.

🏢 Useful application of materials

The strategies are applied to building products labeled ‘waste’ by the industry.

Reuse of discarded yet still usable product, for the same purpose, by a different user.

🏢 Reuse

The doors, windows, service installations, and even furniture are flexible compared to the building structure. If dismantled carefully, they can be reused elsewhere for the same or different purposes.

Repair and maintenance of broken or malfunctioning product, to enable continuation of its original function.



🏢 Repair

Refurbishing and/or modernising an older product, so that the improved version can be used in the product’s original function.


🏢 Refurbish

Using discarded products or their parts in new products with a different function.


🏢 Repurpose

Processing of materials to achieve the original high-quality or reduce to low-quality.



🏢 Recycle

Currently, the best practice worldwide for dealing with concrete and brick debris is to recycle it. The debris is collected, transported, manually or mechanically sorted, washed, crushed, and recycled into new building materials and products.

Impacts

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Industries

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The principles of a circular economy concern designing out waste, regenerating ecosystems and keeping items in use. Decoupling the economy from material flows—improving the rate of resource productivity faster than the economic growth rate—is also a consistent guide. By evolving with the growing number of applications of circular economy principles, and consolidating these strategies across thematic areas, Circle Economy’s Key Elements Framework (KE) renders the elements of the circular economy salient and serves as a basis to derive contextual strategies and interventions. 


The Framework consists of:
- Core Elements: Activities directly handling product or material flows; and uniquely,
- Enabling Elements: those that remove obstacles for core actors.


Key elements of the circular economy

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Circle Economy's framework of strategies and activities that define the circular economy

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**These 17 Goals recognize that ending poverty and other deprivations must go hand-in-hand with strategies that improve health and education, reduce inequality, and spur economic growth – all while tackling climate change and working to preserve our oceans and forests.**

The SDGs build on decades of work by countries and the UN, and especially on the Millennium Declaration adopted in September 2000 at UN Headquarters in New York which let to the elaboration of eight Millennium Development Goals (MDGs) to reduce extreme poverty by 2015.

In 2015, the Paris Agreement was signed. A major blueprint came out of this: The Sustainable Development Goals: 17 overarching goals—and 169 targets—that governments are aiming to meet by 2030. Significant progress has been made in terms of poverty, health and inequality, but there's still a way to go. This is where the circular economy comes in: by circulating resources multiple times, the circular economy tackles issues of scarcity and allows all to access what they need—without overburdening the earth. If it's implemented in a holistic way—affording attention to social considerations and the fair distribution of resources— it also offers a pathway for achieving the SDGs; and the link between the two is ever-growing. To read more about the link between the SDGs and the circular economy, click [here](https://www.circle-economy.com/blogs/how-the-circular-economy-can-help-us-reach-the-sustainable-development-goals).

It is the Division for Sustainable Development Goals (DSDG) in the United Nations Department of Economic and Social Affairs (UNDESA) which provides substantive support and capacity-building for the SDGs and their related thematic issues. TheDSDG plays a key role in the evaluation of UN systemwide implementation of the 2030 Agenda and in advocacy and outreach activities relating to the SDGs. In order to make the 2030 Agenda a reality, broad ownership of the SDGs must translate into a strong commitment by all stakeholders to implement the global goals. DSDG aims to help facilitate this engagement.
Alongside this, the annual High-level Political Forum on Sustainable Development serves as the central UN platform for the follow-up and review of the SDGs.
In addition, the UN Secretary-General presents an annual SDG Progress report, which is developed in cooperation with the UN System, and based on the global indicator framework and data produced by national statistical systems and information collected at the regional level.

To read more information: [https://sdgs.un.org/goals](https://sdgs.un.org/goals)

Sustainable Development Goals (SDGs)

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Based on the work of [Bocken et al. (2016)](https://www.researchgate.net/publication/309699661_Product_design_and_business_model_strategies_for_a_circular_economy), the Four Flows Framework serves as a simple framework for managing resource flows in a circular economy by using less (Narrow), using for longer (Slow), using again (Cycle), and using clean, regenerative materials and energy (Regenerate).

These different principles of circular economy can be applied to our socioeconomic metabolism: we can design stocks like buildings, infrastructure, machinery, and vehicles to be rich resource mines for the future, and design manufactured goods and consumables to be cycled and made regenerative. Furthermore, the focus must also centre on getting more value out of fewer materials. Achieving the aims of a circular economy—minimising material use, regenerating the Earth, and preventing material losses—can be done through these four key strategies mentioned above.

Source: Circle Economy. (2023). *[The circularity gap report 2023](https://www.circularity-gap.world/2023)* (p.22). Amsterdam: Circle Economy. 

Four Flows Framework

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This framework surpasses the famous 3R (Reduce, Reuse, Recycle). The nine strategies Refuse, Rethink, Reduce, Reuse, Repair, Refurbish, Remanufacture, Repurpose, and Recycle and Recover provide a clear and actionable roadmap for a circular transition. 

Strategies at the top of the hierarchy, such as Refuse, Rethink, and Reduce, are the most effective at increasing a construction project's circularity level. These strategies focus on avoiding or minimising resource use and waste from the project's conception.

That is why a clear hierarchy exists where higher-level R strategies are preferred, and lower-level strategies are deemed more linear. 

In the original 9R framework, the last strategy, Recover, is often considered non-circular since it consists of energy recovery from material waste incineration, which is why it was left out of the scope of this case study collection.

They are applied to the built environment sector here as part of the [Realdania ](https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.realdania.org/&ved=2ahUKEwiF74KezMyJAxUpUaQEHURhOOEQFnoECBYQAQ&usg=AOvVaw0o-XWvSka80KCHtCG6XDS3) project.

🏢 9R Framework

  Auf dem Lagerplatz Winterthur stocken wir eine bestehende Lagerhalle auf: mit dem Ziel, ausschliesslich bereits vorhandene Bauteile aus Rückbauten zu verwenden. Der Planungsprozess kehrt sich dabei um. Er beginnt mit der Materialsammlung und verändert sich mit der voranschreitenden Suche nach unterschiedlichen Bauteilen ständig von Neuem. Auf die Wahl des Bauteils folgt das Ausmessen, Inventarisieren und Katalogisieren: Um ein Bauteil wiedereinzusetzen, brauchen wir möglichst genaue Informationen. So entsteht in einem ständigen Abwägen der Entwurf: Die Struktur der Halle 118 bilden Stahlträger, die einst die Coop Verteilzentrale auf dem Lysbüchelareal in Basel stützten. Zugänglich werden die vier neuen Geschosse durch eine Stahlaussentreppe vom ehemaligen Bürogebäude Orion in Zürich. Von dort kommen auch die Granitfassadenplatten, welche wir neu zu Gehbelägen auf den Balkonlauben umfunktionieren. Aluminium-Isolierfenster sowie ein rotes Fassadenblech aus Winterthur und Zürich werden als Verkleidung verwendet. Ergänzend setzen wir bewusst natürliche Baustoffe wie Holz, Stroh und Lehm ein. Sie werden wie auch die wiederverwendeten Baustoffe mit minimalem Energieaufwand verarbeitet und garantieren ein exzellentes Raumklima. So entsteht Platz für zwölf neue Denkstuben, Werkräume und Ateliers. Diese sammeln sich auf jedem Stockwerk um eine Gemeinschaftsküche. Jedes Geschoss ist über Lift und Aussentreppe erreichbar sowie mit Sanitärräumen und grosszügigen Balkonlauben ausgestattet. Mit dem K.118 gelang es dem Baubüro in situ, den Fussabdruck in der Erstellung um 60% gegenüber einem vergleichbaren konventionellen Neubau zu verringern. «…so wäre das ultimative Ziel wahrer zirkulärer Architektur ein Prozess, bei dem niemals Abfall
produziert und somit auch keine graue Energie verschwendet wird.» Zitat aus unserem "Bauteile wiederverwenden"-Buch «Der Prozess ist durch ein ständiges Zurückgehen gekennzeichnet – oder besser gesagt: durch
andauernde Zirkel.»
Denn um vom Linearen zum
Zirkulären zu kommen, ist eine gründliche Neuvermessung des Oberstübchen nötig. Eine
Besichtigung des K.118 kann dabei helfen. Es ist ein Leuchtturmprojekt, nicht für das Stadtmarketing
von Winterthur, wohl aber als Tatbeweis für das grüne Bauen. Zitat von Benedikt Loderer «Niemand dürfte klarer den Verdacht entkräften, dass ‘Wiederverwendung’ sei in der
Architektur zwangsläufig gleichbedeutend mit ‘Gebastel’» Zitat von Herrmann Czech Der K.118 wurde ausgezeichnet mit:

Prix Acier 2021 – RecognitionHolcim Award for Sustainable Construction – Global & European Gold Winner Das Buch zum Projekt:

Bauteile wiederverwenden – Ein Kompendium zum zirkulären Bauen

Winterthur

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Baubüro In Situ

Oberli Ingenieurbau AG

Wetter AG

Josef Kolb AG

<p>K118, located in Winterthur, Switzerland, is a pioneering project that transformed a former carpentry factory into a mixed-use building for workshops and think tank offices. Completed in 2021, the renovation and expansion leveraged circular construction principles, including reuse, repair, refurbishment, repurposing, and recycling.</p>