Brussels' ZIN Project: The European benchmark for circularity in construction

How do you embed circularity into one of Europe’s largest real estate projects?
For the ZIN project, several companies of the CFE Group consorted with Sustenuto to turn circular ambitions into measurable results—achieving 97.8% Cradle to Cradle Certified certification by weight. From reusing 95% of materials from the old WTC towers to transforming procurement processes, this case shows how public-private collaboration can drive real change in the built environment.

Introduction

For the ZIN project, a consortium was formed named Open Minds, composed of companies from the CFE Group. They are a multidisciplinary company with over 2,900 employees and €1.18 billion in annual revenue, active in real estate development, multitechnics, construction, and sustainable investments. CFE Group is helping shape the future of sustainable construction through its pivotal role in the ZIN project. This landmark real estate development in Brussels spans 114,000m² of above-ground space, making one of the largest in the city in the past decade and a European flagship for circularity.

A New Benchmark for Circular Construction

Commissioned by Befimmo in collaboration with the Flemish government, the ZIN project was designed from the outset to integrate circular economy principles. Open Minds was tasked with implementing these principles across the project, including:

• Developing a material passport for the building

• Meeting Cradle to Cradle (C2C) Certified certification targets

• Meeting Volatile Organic Content (VOC) emission targets to improve indoor air quality

The project’s circularity goals were ambitious:

• 95% of materials from the old WTC towers were to be reused or recycled

• 95% of new building materials (by weight) for the offices of the Flemish Government need to be C2C certified

This included certifying complex materials such as concrete, glass, and paint, with specific targets like C2C Certified Silver for concrete and C2C Certified Gold for paint.

The Challenge: Circularity at Scale

Circularity in construction is still emerging, and the ZIN project pushed its boundaries. Suppliers were often unfamiliar with C2C Certified standards, and many materials had never been certified before. This created complex procurement challenges, requiring:

• Supplier education and engagement

• Negotiations with manufacturers

• Alignment with strict certification criteria

Open Minds had to navigate a complex ecosystem of architects, developers, and suppliers—whilst learning to innovate within new procurement frameworks.

Sustenuto’s Role: Strategic and Operational Support

To meet these challenges, Sustenuto partnered with Open Minds to support the project across three key dimensions:

1. Circularity Implementation

Sustenuto helped translate  project circularity requirements into actionable steps. This included  the use of healthier materials with significantly lower VOC emissions that resulted in an overall improved indoor air quality.

2. Cradle to Cradle Certification

We worked closely with Open Minds and selective suppliers to guide them through the C2C Certified certification process. Even when certification seemed unfeasible—such as with certain doors or concrete products—we helped find solutions.

3. Procurement and Innovation

Open Minds adapted its procurement processes to align with circularity goals. This meant engaging suppliers early, guiding them through certification, and ensuring transparency and compliance throughout the supply chain.

The Results: A Model for Future Projects

The ZIN project achieved remarkable results:

• 97.8% of new materials by weight were C2C Certified

• Procurement processes were transformed to support circularity

• The project contributed to the revitalization of the neighborhood

More than just a successful project, ZIN is now a model for circular construction—showing how public-private partnerships can drive meaningful change in the built environment.

Key Takeaways

• Circularity embedded at scale: From demolition to new construction

• Cradle to Cradle Certified certification achieved: Across a wide range of materials

• Procurement innovation: Suppliers engaged and supported through certification

• Public-private collaboration: A blueprint for future sustainable development