According to the European Commission, construction and demolition waste is one of the largest waste streams in the EU. Despite its recyclability, end-of-life building glass is rarely recycled into new glass products. Instead, it is often crushed and mixed with other construction materials, eventually ending up in landfills or used as low-quality backfill material, cutting short the valuable lifecycle of these resources.
Using cullet in float glass production reduces CO₂ emissions
Research indicates that up to 60% cullet can be used in float glass production. For every ton of cullet used, 1.2 tons of raw materials are saved. This reduces the need for mining, processing, and transporting silica sand. Additionally, CO₂ emissions from glass manufacturing decrease by 250–300 kg for each ton of cullet added to the furnace. High-quality cullet allows the float process to continue without modifications or compromises to the final product’s quality. Glass is fully recyclable and can be melted and reused an infinite number of times. In an optimal recycling system, the glass loop remains closed, ensuring that the material stays within the glass industry and doesn’t exit the production cycle.
The carbon footprint of reusable windows is zero
The construction and demolition industry is already transitioning toward resource efficiency in line with the UN Sustainable Development Goals. Alongside material recycling, the reuse potential of windows has also been recognized. Interest in this is growing, partly due to the EU Taxonomy Regulation (Section 4: Transition to a Circular Economy), which encourages investors to prioritize the reuse of building components. Reusable windows have a carbon footprint of zero.
The architectural glass industry could exemplify scalable circular economy practices
Most old windows currently end up as crushed concrete rather than being recycled. Window reuse is still in its experimental phase, but there is potential to build a profitable business model around it. Windows are often replaced for energy efficiency or due to poor condition. The removed windows can be repurposed for new applications, such as partition walls or greenhouses. If some of the used windows are in poor condition, intact panes can be salvaged as-is, while the rest can be processed into cullet for new glass production.
The Hegla IG2Pieces device adds value to defective and end-of-life insulated glass units
To address these challenges, Hegla has developed the IG2Pieces device, which separates the glass from insulated glass units (IGUs) while preserving their original dimensions. The machine cuts around the IGU, allowing intact glass panes to be separated from spacer bars and sealing materials. Recycled glass separated in this way is significantly more valuable than the old IGUs, which are often discarded.
The architectural glass industry has the potential to be a perfect example of a scalable circular economy. Recycling glass within the glass industry reduces energy consumption, the use of natural resources, and CO₂ emissions.
Contact Eero for more information.
(1: GPD 2019 Conference Proceedings, Rethinking the Lifecycle of Architectural Glass DeBrincat G., Babic E., ss. 267-272.