AGC and TRE HOLDINGS CORPORATION have conducted a demonstration in Suwa City, Nagano Prefecture, where Shinshu Takeei (a member of the TRE Group) is based. The demonstration involved horizontal recycling of window glass attached to aluminium sashes (hereinafter “window glass waste”). The purpose of this demonstration was to regenerate window glass waste into glass of an equivalent quality to the original product, thereby promoting resource circulation and contributing to the reduction of industrial waste that would otherwise be sent to landfill.
In Suwa City and its surrounding areas, Shinshu Takeei collected and disassembled window glass waste generated at demolition sites. Subsequently, TRE GLASS CORPORATION, also part of the TRE Group, processed the glass portion into cullet (recycled glass scraps) and conducted quality checks. AGC then verified the process of manufacturing new flat glass using this cullet.
Roles of each company
- Shinshu Takeei: Collection and disassembly of window glass waste; cost analysis and logistics network study.
- TRE GLASS: Production of glass cullet and quality inspection.
- AGC: Process verification for manufacturing flat glass using cullet at the AGC Yokohama Technical Center (YTC).
In Japan, window glass waste generated from buildings is estimated to amount to at least 500,000 tonnes annually, and most of it is currently disposed of in landfills or reused for lower‑quality applications through down-cycling.
This demonstration horizontally recycles window glass waste back into the same application of equivalent quality, aiming to reduce industrial waste. In addition, by increasing the ratio of cullet used in glass manufacturing, the initiative seeks to lower greenhouse gas (GHG) emissions and conserve natural capital by reducing consumption of virgin raw materials such as silica sand and soda ash.
While metal frames from discarded windows have typically been bought as valuable scrap, there has been little development of a reliable mechanism for purchasing the glass itself as a valuable resource, posing challenges to economic sustainability. In this demonstration, AGC and TRE calculated the costs of each step in the horizontal recycling process for window glass waste and verified the overall economics across the supply chain. Going forward, the two companies will evaluate the economic feasibility of glass recycling and aim to build a nationwide framework to promote resource circulation of window glass.