Cullet refers to recycled glass that has been cleaned, sorted, and crushed into small, uniform pieces for reuse in the production of new glass. In the context of construction, cullet is often used in the manufacturing of fiberglass insulation, glass tiles, countertops, and energy-efficient windows. It is available in two main types: post-consumer cullet (from used glass containers) and pre-consumer cullet (scraps from manufacturing processes).
In residential and commercial construction, cullet is valued for its sustainability benefits. Incorporating cullet into production reduces energy consumption because recycled glass melts at a lower temperature than raw materials. It also reduces the need for mining new resources, making it a critical material in green building practices and LEED-certified projects. While cullet itself is not usually handled directly by builders, its presence in materials like insulation and architectural glass is a marker of eco-conscious sourcing. It’s distinct from terms like “slag” or “ash,” which are byproducts of other manufacturing processes and not reused as cleanly in glazing applications.
For example, as a LEED inspector I might note: “I recommend verifying the manufacturer’s environmental claims, as the fiberglass insulation product includes post-consumer cullet for added sustainability.”
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