Closing the loop for float glass has remained one of the most difficult circularity challenges in construction. Unlike container glass, flat glass from end-of-life windows and façades is rarely recycled into new flat glass, mainly due to contamination from sealants, spacers, rubber, metals and coatings. As a result, global recycling rates remain extremely low, less than 1% of float glass worldwide, as highlighted in McKinsey’s 2023 circularity research.

Pilkington Italia is now proving that post-consumer recovery can work at industrial level. The company has completed a circularity pilot project focused on retrieving glass waste from end-of-life windows and façades installed in buildings, refining it into high-quality cullet and reintroducing it into the flat glass manufacturing process.

The pilot was carried out at a construction site in the province of Bergamo, involving several partners across the value chain. PM Serramenti handled the removal of old window systems using a selective demolition method, designed to separate materials already during dismantling. Frames were placed in dedicated containers, while the insulating glass units (IGUs) entered a specialised treatment process where they were cleaned, fragmented and stripped of unwanted components such as rubber, aluminium and other metals.

Once processed, the recovered cullet was delivered to the Pilkington Italia plant and subjected to rigorous optical and chemical inspections. This step was essential to verify that the recycled material met the strict standards required for flat glass production. After approval, the post-consumer cullet was successfully reintroduced into production, delivering finished glass fully compliant with regulations and internal quality specifications.

Beyond technical success, the project confirms the climate value of flat glass recycling: each tonne of cullet used can avoid approximately 700 kg of CO₂ emissions. Delivered through the renew: glass initiative, this pilot sets a concrete, traceable model for scaling post-consumer glass recovery across the construction sector.