Sustainability has become an important part in research and product development. Yet, I believe, as do many others, that one essential question still receives too little attention: What happens at the end of a product’s life, and how can resources be kept in circulation? A product may be energy-efficient, bio-based or associated with lower production emissions, but this does not automatically make it circular. If these questions are addressed only at the product’s end-of-life or once product development has been completed, many circular options may no longer be technically or economically feasible. Circularity must therefore be considered from the outset. This is particularly relevant for construction products, as construction and demolition waste accounts for more than one third of all waste generated in the EU. Insulation materials may remain in buildings for decades and are often connected to other components through adhesives, binders or complex installation systems. Decisions concerning material composition, installation and dismantling can therefore determine whether their value can later be retained or whether they become difficult-to-process construction waste. 

Beyond Recyclability 

Sustainability and circularity are closely connected, but they address different aspects of product development. Sustainability takes a broad perspective on environmental, economic and social impacts across the life cycle. Circularity focuses on keeping resources, products and materials in use for as long as possible. Circular strategies can support sustainability by reducing resource use and waste, but their benefits should always be assessed from a broader sustainability perspective. In this context, the R-strategies of the circular economy provide a practical framework by prioritising options according to the value they retain. Although many industries still focus mainly on recycling, higher-value strategies such as refusing, rethinking, reusing, repairing and refurbishing should be considered first, whenever they are compatible with environmental and social objectives, technical performance requirements and economic feasibility. In case these options are no longer viable, materials can be recovered and returned to the economy as secondary raw materials. 

Against this background, the range of circular strategies available at later stages is largely determined during product development. Circularity must therefore be embedded in the design process from the outset. “Design-for-X” approaches can support repair, lifetime extension and recycling by making products modular, separable and easy to dismantle. For insulation materials, this includes considering whether production residues can be reintegrated, whether materials can be separated from surrounding building components and whether they can be reused or repurposed before recycling is considered. Yet, design alone is not sufficient, especially for products that may remain in use for decades. The information needed to recover their value must also remain accessible. Digital Product Passports, Material Passports and Digital Building Logbooks can document which materials were used, how they were combined and how they may later be separated, reused or recycled. For long-lived buildings, such documentation helps ensure that relevant knowledge is still available when renovation, dismantling or end-of-life decisions are made.