The construction industry is one of the biggest sources of global warming. Much of its impact comes from demolishing buildings and wasting valuable materials such as concrete, steel, and glass. Two professors at ETH Zurich — Catherine De Wolf and Maria Conen — are working to change this. They promote a circular economy in architecture, encouraging the reuse of materials and the renovation of existing buildings instead of replacement.

Reuse Instead of Demolition

De Wolf, Professor of Circular Engineering for Architecture, believes demolition should be the last option. She urges architects to renovate, adapt, or extend buildings whenever possible. If that is not feasible, materials should find a second life in new projects.

A strong example comes from the Centre Pompidou in Paris, where the museum’s glass canopy was reused as partition walls in a new office building. The project, created with Maximum Architecture and other partners, shows how creative design and engineering can reduce waste while saving carbon.

Preserving Identity Through Renovation

Architect and ETH Professor Maria Conen also supports reusing what already exists. Her practice focuses on renovation and adaptive reuse, helping to preserve both materials and cultural identity. “When you demolish houses, you also erase their history,” she says. One of her recent projects in Winterthur, Switzerland, transforms a century-old bus depot into housing. The design keeps the original steel beams and roof structure, combining them with timber and reclaimed glass to conserve the building’s embodied energy.

Making Circular Design Practical

Despite its environmental benefits, circular construction still faces practical barriers. Reuse can be time-consuming and costly, while new builds are often cheaper. De Wolf suggests that automation and digital platforms could make reuse easier. She is developing an online marketplace for reclaimed materials and supports the use of digital material passports that track a material’s origin, use, and quality.

Designing for disassembly is also key. Buildings made with screws or interlocking systems can be taken apart and reused, unlike glued constructions. This modular approach supports repair, adaptation, and reuse throughout a building’s life cycle.

Educating the Next Generation

ETH Zurich is helping to scale these ideas through its Certificate of Advanced Studies in Repair and Maintenance, aimed at professionals in architecture, engineering, and industrial design. The programme teaches practical methods for repair, reuse, and resource efficiency, giving future designers the tools to drive sustainable change.

By rethinking how buildings are designed and maintained, architects and engineers can extend the life of materials — and reshape the built environment for a circular future.

Source: ETH Zurich
Image: Alexandre Attias / Maximum Architecture