With advances in glass manufacturing there are many more options to choose from for a project. Depending on the requirements laminate safety glass, toughened glass, glass coated for UV protection or even insulated glass units may be used instead of traditional Annealed glass.
The biggest downside of these technological advances is that with added “ingredients” in the mix, glass can become less recyclable. This directly influences the advantages a closed-loop glass recycling system has, that can be easily achieved with Annealed glass.
Glass has the potential to be recycled indefinitely but with the enhanced architectural glass units there are components that are not easy to separate and re-use. Heat treated or toughened glass, even though a pure form of glass can be problematic to re-shape or re-purpose. According to NSG Pilkington the manufacturing of one square meter of low-E double glazing leads to the emission of 25kg of CO2.
Some waste glass can be used in the manufacture of glass wool insulation, aggregates and bollotini products. This, however, has a low value and a non-circular material stream. So even though the glass is re-purposed, this is not a closed-loop recycling system.
Having stated the importance of recycling, it’s currently seen as a last resort and the least sustainable approach, as it requires the most primary energy to return the glass to a raw material state. Because of this there will have to be changes not only in recycling of glass, but also in the planning of new buildings. The flat glass industry is looking into using more recycled glass as a standard in new projects. This will in turn encourage the construction and demolition industries to look at innovations to become more resource efficient and circular in their practices.
Glass does not have the lifespan of concrete or brick, but it can be used to boost the green foot print of new buildings in various ways. By becoming again more recyclable and by being multi-functional, for example assisting with internal climate control and even being used as collectors for solar energy, glass can truly be a proudly environmentally sustainable material in a closed-loop recycling system.