UMSICHT researchers develop resource-saving glass-film roofs
Glass roofs adorn railway stations, leisure pools and even shopping arcades. However, the often heavy panes consume a lot of resources. Together with industrial partner Wolfgang Block Industrie- und Gartenbau GmbH & Co. KG, Fraunhofer UMSICHT is therefore researching roofs made of glass film.
Glass roofs – what looks light and bright is actually heavy and consumes a lot of resources. The translucent overhead glazing usually consists of several panes of insulating glass. Fraunhofer UMSICHT is therefore researching film-based materials to make roofs translucent. In the ‘Light-Light-Roof’ project, the researchers are developing an innovative, lightweight and modular lightweight construction system: a combination of a glass-foil module system and an inner roof made of mobile, translucent and IR-reflective fabric.
Architecture relies on ETFE film
©Fraunhofer UMSICHT, Drone view of the ALTMARKTgarten in Oberhausen
The modular system consists of ETFE film covering (ETFE: ethylene tetrafluoroethylene copolymer) and toughened safety glass. ETFE now allows up to 95 per cent of light to pass through. On the one hand, the materials are better characterised. On the other hand, the researchers were able to overcome production-related obstacles, for example through bonding and welding. These building envelopes are therefore becoming increasingly important in architecture in particular. For example, the ‘Allianz Arena’ in Munich and the ‘Water Cube’ in Beijing utilise ETFE.
Save weight
Heavy glass roofs have a detrimental effect on the overall construction, material transport and installation. “Thanks to the structure and the combination of materials, the combination of film and glass achieves weight savings of up to 75% compared to conventional multi-pane glass systems. And that with increased functionality at the same time,” explains Dr Holger Wack, Deputy Head of Product Development. In addition, there are further, as yet unquantifiable savings in building construction: for example, architects can design slimmer and lighter buildings, as the supporting structure has to bear significantly less load and snow. This makes Light-Light-Roof interesting not only for horticulture and the plant trade but also for other sectors, such as the planning and construction of building façades.
©Fraunhofer UMSICHT, Installed glas-film systems in the ALTMARKTgarten
Adapt to solar radiation, temperature and amount of light
With the circulating air between the glass pane and film, the system can also ideally interconnect with the building’s exhaust air, e.g. in winter by defrosting snow or ice loads or for thermal insulation. In addition, the inner roof is based on an IR-reflecting fabric. Depending on the solar radiation, temperature and amount of light, the researchers can adjust the inner roof as required. To do this, they are developing a measurement, control and regulation technology (MCR) in the project that is customised to the building and user requirements. They are integrating this into the system and preparing for digitalisation using a cloud-based solution.
First use in the Altmarktgarten
In the ‘Altmarktgarten Oberhausen’ rooftop greenhouse, the researchers are testing the glass-foil roof under real-life conditions on a planned roof area of 160 m2 in year-round operation. In the seminar rooms of the building-integrated rooftop greenhouse, which has been in operation since 2019, the project team wants to present the project across all sectors. In this way, they are preparing for commercial utilisation. In particular, they are addressing the expanding market for production systems located in urban areas.