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The Heliotrope is a design of environmentally friendly housing by the German architect Rolf Disch. Three such buildings exist in Germany; the first experimental version was built in 1994 as the architect's home in Freiburg im Breisgau, while the other two were used as exhibition buildings for the Hansgrohe company in Offenburg and a dentist's lab in Hilpoltstein in Bavaria.
Several different energy generation modules are used in the building including a 603 sq ft (56.0 m2) dual-axis solar photovoltaic tracking panel, a geothermal heat exchanger, a combined heat and power unit (CHP) and solar-thermal balcony railings to provide heat and warm water. These innovations in combination with the superior insulation of the residence, allow the Heliotrope to capture anywhere between four and six times its energy usage depending on the time of year. The Heliotrope is also fitted with a grey-water cleansing system and built-in natural waste composting.
At the same time that Freiburg ’s Heliotrope was built, Hansgrohe contracted Disch's architecture practice to design and build another Heliotrope to be used as a visitor’s center and showroom in Offenburg, Germany. A third Heliotrope was then contracted, and built in Hilpoltstein, Bavaria, to be used as a technical dental laboratory. Disch's unique design accommodates different utilizations from private residences to laboratories, and nevertheless maintains the structure's positive energy balance.
Disch also designed the Sonnenschiff office complex.
PlusEnergy is a coined concept developed by Rolf Disch that indicates a structure's extreme energy efficiency so that it holds a positive energy balance, actually obtaining more energy than it uses. With the completion of his private residence, the Heliotrope, in 1994, Disch had created the first PlusEnergy house in the world. The sheer logic of a home that captures more energy than it consumes made perfect sense to Disch. His next goal in its development was thus the mass application of the concept to residential, commercial and retail space. As the concept further developed and gained financial backing as well, Disch built several more projects with PlusEnergy certifications. PlusEnergy is a simple concept that has been materialized in a technical design. “PlusEnergy is a fundamental environmental imperative,” Disch claims.[not specific enough to verify] Disch believes that passive building isn’t enough because passive homes still emit CO2 into the atmosphere.
Environment and energy needs
The house is designed to face the sun with its triple-pane windows (U = 0.5) during the heating months of the year and turn its highly insulated back (U = 0.12) to the sun during the warmer months when heating isn't necessary. This significantly reduces heating and cooling requirements for the building throughout the year, which are provided for by a heat pump, while hot water is provided by vacuum-tube solar panels.
Photovoltaic solar panels with a rated power of 6.6 kW on its roof provide five to six times more energy than the building uses, making the building energy positive (PlusEnergy). To further improve energy capture, the panels also rotate independently of the building to follow the sun, while being able to adapt its orientation in case of strong winds.
Water usage and natural waste management
In order to limit water usage, a gray water circuit (for washing dishes and clothes) is used. It also collects rainwater. Waste water is purified in a vegetated cascade pond outside the edifice.
Natural waste and excrement are dry composted in the structure as well.
One of the main attractions of the house, apart from its low energy needs, is its rotating view. As the building turns according to the sun's position, the view changes. This feature was later developed into a rotating hotel concept.
The roof deck includes a sun and viewing deck, as well as a garden terrace. The solar panels can be used for sun or rain protection while on the roof terrace.
All floors are accessible from the spiral staircase, reducing surface loss through hallways and corridors.
- 2008 German Sustainability Award
- 2007–08 Japanese PEN-Magazine Creativity Award
- 2005 Wuppertal Energy and Environment Prize
- 2003 Global Energy Award
- 2002 European Solar Prize
- 2001 Photovoltaic Architecture Prize Baden-Württemberg
This article needs additional citations for verification. (July 2022)
Heliotrope in Vauban, Freiburg, 1994
- "Home". rolfdisch.de.
- Official website of the Heliotrop (in English)
- Freshome.com: brief description with pictures (archived 2014)
- Article in Chinese with some pictures of the house (in Chinese)
- Solar Settlement and Sun Ship Video
- PlusEnergy (archived 2014)