German Federal Energy Initiative Launches FLEX-G Project

The FLEX-G Cooperative Research Project has launched under the Energiewendebauen German federal construction technology initiative.

Funded by the German Federal Ministry for Economic Affairs and Energy, the research project’s main goal is to investigate technologies for the manufacturing of translucent and transparent membrane roof and facade elements with integrated optoelectronic components. The focus lies on a switchable total energy transmittance, or g-value, and on flexible solar cell integration to significantly contribute to both energy saving and power generation in buildings. Solar modules and a variety of energy management systems are well established in small and large buildings to optimize their energy balance both by generating electrical energy and by minimizing required power for heating, ventilation and air conditioning.

“Membrane facade and roof elements will be functionalized with electrochromic films [that] allow switching of the transmission of visible light and thermal radiation by applying an electrical voltage,” said John Fahlteich, project coordinator. “The energy required for that is made available through flexible organic solar cells. Within the project FLEX-G, we aim to develop dynamic processing and deposition techniques in a way that they are applicable not only for flexible, membrane-based building envelopes, but also for glass-based systems.”

Within the project duration of three years, FLEX-G will investigate processes that allow the deposition of electrochromic layer stacks directly on an ethylene tetrafluoroethylene film surface. The flexibility of the film enables the use of economical, efficient and high throughput roll-to-roll fabrication processes. A 36-m² large membrane roof prototype will demonstrate both the electrochromic components for switching the total solar energy transmittance and the flexible organic solar cells for electrical power generation.

With integration of flexible optoelectronic components on vaulted building envelopes, FLEX-G will contribute considerably to reducing the primary energy consumption of buildings. This is also in line with the goal of the German federal government to reduce primary energy consumption in Germany to up 50 percent by 2050.