Algenhaus, Bioreactor house in Wilhelmsburg, Hamburg, Germany

The Algenhaus is a residential building in Wilhelmsburg with special glass panels on its facades where microalgae grow. These panels on the southwestern and southeastern sides create a green surface that changes constantly throughout the day.

The building was developed as an experimental project and completed in 2011. It was created as part of a major exhibition for new architectural ideas in Hamburg.

The name Algenhaus ("algae house") comes from the microalgae cultivated in its glass facade panels, which residents and passers-by see changing colour as the biomass circulates. The 129 panels hold 3,500 litres of water; air bubbles released from below keep the algae moving. The biotech firm SSC decides when the algae are dense enough to be harvested, and the dried biomass is valued at about 30 euros per kilogram.

The building can be viewed and photographed from outside, and the algae panels are most visible on sunny days. Interior access is limited, so visitors should check in advance whether guided tours are available.

The building was among the first in the world to use microalgae on a large scale for energy production directly in its facades. This technology allows the algae to produce heat and biomass while filtering natural light into the building simultaneously.