Japan Launches First Window Glass Circular Recycling Project

Sekisui House, Ltd., Daiei Kankyo Co., Ltd., and AGC Inc. 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. *1 In this project, 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”). This is Japan’s first circular model in which a homebuilder, a recycler, and a glass manufacturer collaborate to enable horizontal recycling of window glass.

Background: Current Status and Challenges in Window Glass Recycling 

In Japan, more than 500,000 tons of waste window glass are generated annually from the demolition and renovation of buildings. At present, much of this waste glass is landfilled or downcycled (cascade recycled) into lower-quality applications, or repurposed for other uses, rather than being recycled back into window glass.

Overview of the Demonstration Project and Expected Impact 

By establishing this circular model, the project is expected to: advance resource circulation by enabling closedloop 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 with newly extracted raw materials.

Roles of Each Company

In this demonstration project, the recovered discarded sashes will be dismantled by Daiei Kankyo. A specialized glass recycler will then process the recovered window glass into high-purity cullet (glass scrap). 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 glassin 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

Through this closed-loop supply chain collaboration in the demonstration project, the three companies aim to develop an effective and scalable model that can be applied in collaboration with a broader range of waste generators in the future.

Reference Information on Each Company’s Initiative

Sekisui House’s “House to House” Project Aims for Circular Homes by 2050

Sekisui House’s House to House initiative outlines a pioneering circular economy strategy for the housing industry, aiming for homes and materials to be reused and recycled into new homes by 2050. The project is focusing on efficient resource use and maximizing value throughout a home’s lifecycle. By rethinking more than 30,000 components and utilizing recycled, reusable, and renewable materials*2, Sekisui House seeks to lead a shift toward sustainable housing. Collaboration with suppliers, universities, and industry partners supports innovation and wider adoption of circular practices in residential construction.

Daiei Kankyo: Medium-Term Management Plan “D-Plan 2028”

In its Medium-Term Management Plan, D-Plan 2028, Daiei Kankyo positions the advancing of resource-recycling systems as a growth measure and aims to expand the supply of recycled resources to “artery” markets. Through this demonstration, Daiei Kankyo will help build an artery-vein collaboration scheme for horizontal recycling of waste window glass that previously went to landfill, contributing to the realization of a circular economy.

AGC Group: Medium-Term Management Plan “AGC plus-2026 ”

AGC plus-2026 identifies three types of social value the AGC Group provides. Under “Blue planet,” the Group recognizes effective resource utilization as a key opportunity and aims to contribute to a sustainable global environment by expanding horizontal recycling of glass.

Notes
*1 The scope includes rental housing and is limited to low-rise houses up to two stories.
*2 Components whose main materials include recycled raw materials (including reused and renewable materials). Recycling methods are not limited to closed-loop or horizontal recycling.