Every windowpane a second life (Reused insulation glass)

Every year in the Netherlands, more than 90 million kilos of flat glass are removed from buildings, mainly to improve insulation or due to demolition. This glass is largely recycled into glass granules for glass wool and packaging materials. Although recycling is a step in the right direction, the process consumes a lot of energy, and valuable material (flat glass) is lost. Moreover, suppliers of insulation glass must continue to purchase new flat glass.

A circular solution

Reusing insulation glass in new HR++ glass is a much more circular solution and has significant environmental benefits. First, flat glass production is an energy-intensive process with high CO₂ emissions. In addition, suitable sand, a crucial ingredient, is becoming increasingly scarce, and there is a growing import of glass from ever greater distances (resulting in extra transport emissions).

As part of the ambition to be fully circular by 2050, real estate clients increasingly demand the use of recycled materials in construction projects. Recycled insulation glass is a critical step toward a fully circular construction sector. This research project has demonstrated that reusing insulation glass is possible and how it can be done effectively.

Opgrading old insulation glass

The Amsterdam University of Applied Sciences has established a consortium of experts from the entire construction sector, including glass processing companies, consulting firms, demolition companies, contractors, and building owners. Together, they have developed strategies to upgrade old insulation glass to the quality of new HR++ glass and to reuse flat glass after dismantling.

In addition, a method was developed to determine whether it is technically better to reuse the entire insulation glass unit or to reuse both glass panes separately after dismantling. In most cases, dismantling proved to be more practical due to the age of the glass and/or the reduced argon concentration in the cavity (and therefore the insulating quality of the glass).

Circular construction economy

Several partners have now commercially implemented the reuse strategies. The results have been widely shared through publications and seminars. At the final seminar, about 130 interested companies learned how to integrate insulation glass reuse into their operations, contributing to a circular construction economy!