Fluoropolymers such as ethylene tetrafluoroethylene (ETFE) are characterised by the fact that they are durable and weatherproof – as well as being considerably lighter and more flexible than glass. As aesthetically attractive elements for designing roofs and facades, they are used especially for covering large surfaces such as train stations, shopping centres and stadiums.

However, until now, such roof and facade elements were not energetically feasible due to the difficulties of coating them. In the research project FLEX-G, researchers are therefore seeking to find ways of integrating ETFE roofs and facades as active elements in the energy management of buildings. In particular, the researchers are investigating the effect of equipping them with electrochrome building elements for switching the total energy transmittance (g-value) as well as the integration of flexible, organic solar cells. Tests on a 36m²-large membrane roof, equipped in such a way, are to provide information about the energy efficiency of such functional layers.

With a view to achieving series production in future, FLEX-G is examining the possibilities of using a roll-to-roll (R2R) coating method. This will enable a large number of flexible ETFE foils to be equipped at low cost with large-surface functional layers.