Sekisui House, Daiei Kankyo and AGC announced that they will commence a demonstration project in the Kansai region from March 2026 to establish a circular model for recycling window glass in home renovations. This is Japan’s first circular model: window glass will be recovered from discarded sashes generated during renovation work and recycled into new architectural window glass of equivalent quality (a form of “horizontal recycling”).
In Japan, more than 500,000 tonnes of waste window glass are generated annually from the demolition and renovation of buildings. At present, much of this waste glass is landfilled or down-cycled (cascade recycled) into lower-quality applications, or repurposed for other uses, rather than being recycled back into window glass.
By establishing this circular model, the project is expected to: advance resource circulation by enabling closed-loop recycling of window glass, reduce industrial waste and landfill volume, help conserve virgin raw materials used for window-glass production and contribute to lower greenhouse-gas emissions in manufacturing, as recycled cullet can be melted at lower temperatures compared to newly extracted raw materials.
In this demonstration project, the recovered discarded sashes will be dismantled by Daiei Kankyo. A specialised glass recycler will then process the recovered window glass into high-purity cullet. AGC will use the cullet as part of the raw materials to manufacture new architectural window glass that meets the same quality standards as products made from virgin materials.
By adopting the newly manufactured window glass in Sekisui House’s housing products, the initiative gives concrete form to the company’s Circular Design from “House to House,” demonstrating a pathway to reduce environmental impact across the entire life cycle of homes. The three companies will work to simultaneously reduce industrial waste and conserve window-glass raw materials, thereby advancing resource circulation.
Roles and Contributions
- Sekisui House – Collecting and consolidating discarded sashes generated during home renovation work, contributing to horizontal recycling.
- Daiei Kankyo – Dismantling and sorting discarded sashes; builds processes to ensure consistent quality and traceability.
- AGC – Manufactures window glass using cullet derived from discarded sashes as part of the raw materials and supplies it to Sekisui House for use in its housing products, including recycling-friendly THERMOCLINE®.