In your opinion, what are the next steps to take to ensure that reuse solutions for glass are widely accepted in terms of building regulations and economics?
Martien Teich: More and more enquiries show that interest is growing, but there is often a lack of experience and clarity, especially when it comes to legal issues. These uncertainties lead to lengthy case-by- case reviews which cost time and money. Standardised processes are crucial here. Together with the Fachverband Konstruktiver Glasbau (FKG) and the Bundesverband Flachglas (BF), we have published the initial recommendations for action on taking stock and legal issues. This is just the start. We are further developing this in a current research project which is being carried out together with the Glass Competence Centre (GCC) at TU Darmstadt.
Sebastian Wernli: With every project we complete, our expertise grows and our inhibitions decrease. Therefore, we actively seek a dialogue with the industry and provide support during implementation. It is important to learn from successful projects and highlight the processes that work.
What conditions must be met for used glass panes to be reused?
Sebastian Wernli: Clean dismantling is crucial. If you want to reuse panes, you have to treat them as valuable building products from the outset and not as waste. This is the only way to maintain quality throughout all the stages.
Martien Teich: First of all, a precise inventory is required: glass type, coating, condition. Many panes, such as uncoated double insulating glass from the 1980s and 1990s, cannot be reused directly, but they can be refurbished or separated and integrated into new glass units as individual panes. Visual quality plays a key role here, which is tested individually or in accordance with standards.
Sebastian Wernli: In the medium term, the handling of coated glass will also become more relevant as more of it is removed. Currently, however, our focus is on uncoated panes. The aim is to sort the individual panes according to quality. High-quality glass is reused, and the rest is recycled by type.
How realistic is the widespread use of reuse in construction and where are the economic levers?
Martien Teich: Reuse was discussed intensively at glasstec. There was also talk of “low-hanging fruit”, which is the area where reuse is easiest to implement. I see the biggest and easiest entry point in conventional windows in the renovation of office and residential buildings. The dimensions there are often similar and not too large, which simplifies the requirements for statics and breakage behaviour. Findings from this area can help to gradually develop more complex applications such as façades.
Sebastian Wernli: Economically, I always argue with the following two points: Firstly, a whole pane is more valuable than broken glass, so it is generally worth not destroying it immediately. Secondly, reuse is particularly cost-effective when you think regionally. Existing glass accumulates in cities where construction is also taking place. With regional structures, we save on transport costs, reduce emissions and strengthen local value creation. The better this is organised, the more realistic reuse becomes as an integral part of construction practice.
