This week I would like to share a post about the Heliotrope – a self-sustaining, 360° rotating building in Freiburg, Germany. I was introduced to this building in a class during my masters degree program in Biomimetics in Energy Systems at the Carinthia Universtiy of Applied Science in Austria a few years ago. Since I could not find many reports written in English, and no documentary narrated in English on this topic, I thought it might be interesting for English speakers if I translated a German video about the Heliotrope so you can share in learning about it. I still recommend you watch the video, because the animations are quite helpful to illustrate the Heliotrope’s functional principles.
The Heliotrope was built in 1994 by the German architect Rolf Disch who is a pioneer in solar architecture. The building is named after the principle of heliotrope plants that turn their leaves according to the sun’s position to maximize their energy production. This is exactly what the Heliotrope is doing: A gearwheel at the Heliotrope’s base rotates the building 360° throughout the day. Therewith, a photovoltaic panel on the building’s rooftop is always directly facing the sun, which increases the energy efficiency of the Heliotrope. In fact the Heliotrope produces around 9000 kWh per year which is 5-6 times more energy than the building itself requires. The excess energy is fed into the local electricity grid. The rotating of the building also has a second advantage: for instance in summer, inhabited interior spaces like bedroom or living room can be rotated into the shadowed side of the building. By the way, the engine, which is responsible for rotating the building, requires only the same amount of electrical energy as an average energy efficient refrigerator. Furthermore, warm water is generated by solar thermic vacuum tubes that are arranged around the building. The generated warm water is also used to heat the building via a heat exchanger. In case no sun is available for several weeks, a wood pellet oven is used as a backup heating system. Additionally, the Heliotrope is almost a hundred percent waste free. All organic waste products from the kitchen as well as bodily wastes from the toilettes are recycled by a compost unit, which annually creates one bucket of potting soil as a recyclable waste product. A very impressive feature of the building is that it is completely built from wood. There is no other building in the world that includes a central wood column that carries and rotates the entire building’s structure. All rooms inside the building are arranged in a spiral around that central column. More technical details about the Heliotrope’s architecture can be found at www.rolfdisch.de.