There are many ways of reducing energy consumption in buildings. However, while insulating panels, for instance, are usually not immediately visible, aesthetic demands are made on facades. At the same time, facades and windows offer comparatively large and often sunlit surfaces that can be used for renewable energies.

Fraunhofer ISE has joined forces with its industrial project partners to form a research project called “Arkol – development of architecturally highly integrated facade collectors with heat pipes” to examine the possibilities of making this potential available for heat generation. With two million euros worth of financial support from the Federal Ministry for Economic Affairs and Energy (BMWi), two types of facade collectors are thus to be developed to market maturity in the period between January 2016 and December 2019: a strip collector and solar thermal venetian blinds.

The heat-pipe strip collector can be integrated into a facade and flexibly adapted to the building’s architecture. Since it is composed of prefabricated modular elements, the researchers expect production to be low cost.

The venetian blinds, however, have been designed for use between glass panes (e.g. in the glass facade or windows). They are equipped with slats with a spectrally selective coating, from which the sun’s heat is transferred via a heat pipe into a laterally mounted collection duct. The movable slats enable the active regulation of the heat flow.

The simulation models are currently still being measured and calibrated. In 2019, a demonstration facade for both collectors is to provide data based on actual use before the technologies are marketed, which is planned for the following year.