Freiburg im Breisgau
The Heliotrop was the very first plus-energy house in the world and produces three times more energy than it uses. As a rule it follows the path of the sun from east to west so that the glazed exterior catches as much sunlight as possible. However, on hot days it can also make use of an integrated insulated wall in order to provide itself with shade.
To be viewed from the outside, guided tours by appointment.