[prEN 18177] Europe Is Standardizing Circular Construction

A significant step forward in European standardization: prEN 18177 is progressing toward a common framework for circular construction.

In April 2026, I published “A Message from 2050 to the Circular Construction Sector,” arguing that our greatest mistake was attempting to assess circularity without developing the measurement infrastructure needed to verify it. Today, I want to share encouraging progress from the European standardization process.

As a Belgian expert contributing to CEN/TC 350/SC 1, Circular Economy in the Construction Sector, I have been following and contributing to discussions that could fundamentally change how we define, assess, and communicate circularity in buildings and construction products.

🇪🇺 1. prEN 18177: A significant milestone

In May 2026, the committee approved proposals to divide prEN 18177 into two complementary parts:

📘 prEN 18177-1: Terminology: Establishing a common vocabulary for circular construction.

📗 prEN 18177-2: Framework and Principles: Developing a shared conceptual foundation for circularity across the construction sector.

Dr. Valentina Bisinella (Denmark) is the new convenor of CEN/TC 350/SC 1/WG 1 (Framework, Principles and Definitions), succeeding Prof. Lisbeth M. Ottosen. Next, the conveners of WG1, WG5, and WG7 were convened by Evert Shut, Flora Anvarifar and others. This matters because circular construction cannot advance when manufacturers, architects, researchers, and policymakers use the same words to describe different realities.

🔬 2. The real breakthrough: What exactly should we measure?

Recent technical discussions have moved beyond definitions toward a more consequential question:

Should circularity be measured through intentions, technical characteristics, or actual material flows?

The emerging framework connects circularity objectives to three resource-flow strategies:

♻️ SLOW resource flows: Extend service life through durability, maintenance, adaptability, and reuse.

♻️ NARROW resource flows: Reduce the consumption of primary resources and improve resource efficiency.

♻️ CLOSE resource flows: Keep materials circulating through recovery, reuse, and recycling.

These strategies provide a foundation for translating broad circularity objectives into assessment criteria. However, the distinction between a circularity strategy and its measurable outcome remains essential. A building designed for disassembly is not necessarily a building whose components will actually be recovered and reused.

🏗️ 3. A building's end-of-life is not necessarily a material's end-of-life

One particularly meaningful discussion concerns the distinction between:

• End-of-use • End-of-performance • End-of-life • Subsequent use cycles

A building may reach the end of its intended use while its structural components retain decades of functional value. Conversely, a technically reusable component may never be reused because of missing documentation, unsuitable connections, uncertain performance, or economic barriers. This distinction is fundamental to circularity assessment. We must evaluate buildings, products, and materials at their appropriate levels rather than assuming they share identical lifespans.

📊 4. Circularity assessment is becoming a dedicated standardization priority

Another important development concerns CEN/TC 350/SC 1/WG 5, Circularity Assessment. The working group is developing the scope of a proposed standard addressing circularity assessment for construction products, components, and construction works. The group is identifying material-flow analysis as its primary methodological focus, complemented by consideration of:

• Environmental, social, and economic impacts of circular actions • Technical characteristics supporting circularity • Take-back systems and extended producer responsibility • Assessment criteria adapted to different stakeholders and decision-making contexts

This is an important direction, although the assessment methodology remains under development.

🔍 5. Why our research at the University of Liège matters

At the Sustainable Building Design Lab, we have spent years examining what happens to building materials beyond the design stage. Our research includes twenty six circular building case studies and more than 450 structural connections. Through forensic building audits, material inventories, dismantling observations, and lifecycle modeling, we investigate the difference between designed circularity and realized circularity. This evidence reinforces three lessons:

First: Design for disassembly must be supported by evidence of actual disassembly performance.

Second: Material passports must remain useful throughout successive ownership, maintenance, and reuse cycles.

Third: Circularity assessment must distinguish technical reuse potential from the probability of actual reuse.

Our research suggests that future assessment methods could benefit from longitudinal evidence, uncertainty analysis, and reference-class forecasting.

These are research directions we advocate, not requirements already established by prEN 18177.

🎯 6. The next challenge: From common principles to credible evidence

The development of European circular construction standards represents meaningful progress. But standards alone cannot guarantee circular buildings. We still need reliable material inventories, consistent assessment boundaries, documented performance, transparent assumptions, and evidence of what happens when buildings are adapted or dismantled.

My central argument remains unchanged:

Circularity should not be judged by how convincingly a building is marketed, but by how effectively its materials retain value across successive use cycles. The next generation of circular construction assessment must connect standards with real-world evidence. And this raises a question for everyone working in architecture, engineering, manufacturing, demolition, and policymaking: Should a building receive circularity credit for being designed for reuse, or only when its components are demonstrably recovered and reused?

I would be interested in hearing your perspective.

📚 Explore our circular construction research: Sustainable Building Design Lab

🌐 More research and publications: Shady Attia

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