One chain, One truth: How shared data on Madaster delivers full transparency
Case Study:
How Kömmerling Netherlands, GSF Glass group & Siegenia hardware solutions use Madaster to create a highly circular window
A fully transparent value chain, with verified EPDs for all suppliers
Real-time insight into the environmental cost (ECI) of each window configuration
Up to 40% reduction in ECI, proving measurable sustainability gains
The ability to compare and select suppliers based on actual environmental performance
Project background: A shared vision for circularity
Kömmerling Netherlands, part of the international profine Group, a global leader in PVC window and door profiles, strives for minimal environmental impact and maximum circularity. True sustainability requires transparency across the entire supply chain. That’s why Kömmerling collaborates with GSF Glasgroep, a specialist in circular glass, and Siegenia, a supplier of sustainable hardware. With support from Turntoo, they jointly developed the most circular PVC window system currently on the market. Every component, from the frame to the glass, and from the locking system to the hinges, is designed for reuse and contributes to a closed-loop material cycle.
Their mission: to replace theoretical sustainability claims with real, verified environmental data, ensuring that every material choice is transparent, measurable, and optimized for circularity. The key to this? Digitizing environmental impact data through Madaster.
Challenge: From fragmented data to full transparency
To accurately assess the environmental performance of a complete window system, it is essential to gather Environmental Cost Indicator (ECI) data from each supplier of the individual components. This requires close collaboration across the supply chain and is often a complex, time-consuming, and manual task.
Traditionally, manufacturers rely on generic or theoretical data due to the challenges of sourcing actual material and transport data from suppliers. However, this leads to inaccurate assessments, making it difficult to compare suppliers or quantify real circularity improvements.
For Kömmerling Netherlands and its clients, this was a critical challenge. With ESG regulations tightening and market demand for sustainable, verifiable products increasing, they needed a scalable solution to provide instant insight into the environmental impact of each component in their value chain.
Solution: transparent circularity at the press of a button
By implementing Madaster, all key suppliers: Kömmerling Netherlands and its partners uploaded their EPD and LCA data into a centralized database in the Madaster platform. This enabled:
- Real-time ECI calculations for every window system configuration
- Direct supplier comparisons to select the most circular and sustainable components
- A transparent, data-driven value chain—no assumptions, just facts
Three window scenarios for maximum transparency
With Madaster, Kömmerling Netherlands and its partners developed three distinct window configurations, each offering different levels of circularity and environmental performance:
Baseline: Generic PVC window frame + New hardware
• ECI: 102€ (Environmental Cost Indicator)
• Circularity: 44% (window frame) + 46% (hardware)
Current circular window: Recycled frame + Circular glass + New hardware
• ECI: 52€ (Fully circular window now available)
• Circularity: 81% (recycled frame) + 42% (glass)
Future circular window: Recycled frame + Circular glass + Refurbished hardware
• ECI: 9,40€ (Most circular option, launching soon)
• Circulariteit: Even higher with refurbished parts
By managing supplier data in Madaster, Kömmerling Netherlands can instantly calculate the total ECI of a complete window, eliminating manual data collection. Moreover, they can compare multiple suppliers per component, making circular decision-making fully transparent and scalable.
Results: Measurable circularity and competitive advantage
By digitizing and aligning environmental data through Madaster, Kömmerling Netherlands and its partners have achieved:
- A fully transparent value chain, with verified EPDs for all suppliers
- Real-time insight into the environmental cost (ECI) of each window configuration
- Up to 40% reduction in ECI, proving measurable sustainability gains
- The ability to compare and select suppliers based on actual environmental performance
“With the help of Madaster and Turntoo, we can provide data about environmental impact. This enables us and our clients to make informed choices, compare suppliers, and deliver products that are truly circular.”
Jelmer Bijlsma – Sustainability & Innovation Manager, Kömmerling Netherlands
Conclusion: Setting a new standard for circular manufacturing
This project proves that full value chain transparency is achievable – and powerful. By integrating actual data into the design and procurement process, Kömmerling Netherlands, GSF Glass group, and Siegenia have set a new benchmark for data-driven sustainability in the built environment.
As circularity reporting becomes the industry standard, this project serves as a leading example of how manufacturers can take circularity from ambition to reality – one verified data point at a time.
