Bottle glass is one of the most recyclable items around. By contrast, in many communities, it is nearly impossible to recycle window glass. Why the disparity? Though the two products may seem virtually the same, there are actually some notable differences. Bottle glass has a different chemical composition and melting temperature than window glass, meaning the two products can’t be recycled together. Manufacturers creating new bottles have invested in the equipment needed to crush bottles and remelt them. This infrastructure is vital to make recycling work. In addition, bottles are a fairly uniform and easy-to-identify product. Window glass is a trickier proposition. Most windows come attached to metal or wooden frames and have to be disassembled, which is labor intensive and expensive. Picking out the different types of window glass poses a bit more of a challenge. Is the glass tinted or not? Is it safety glass or tempered glass? All these different subsets of window glass also cannot be combined to create a new product. As a result, the industry has said “no” to recycling old windows. However, not all hope is lost. Creative industry professionals are finding other uses for old windows. The glass can be melted and remanufactured into Fiberglas. Ground glass can be incorporated into glassphalt, a glass and asphalt blend, or stirred into the reflective yellow and white paint used on roads. Broken glass is combined with concrete to create terrazzo flooring and countertops. Building REsources in San Francisco tumbles old glass (and ceramics) for landscape, floral and decorative applications. Old windows can also be reused as is. Donate them to a building material reuse company, or use them to construct greenhouses or cold frames for the garden.