The expansion of human habitats from the land to the water, sea or lakes, is not a new idea. The search machine Google supplies an overwhelming number of results for the search term “life on water” by now. A well-known example from practice are the artificial islands on the coast of Dubai, United Arab Emirates. Many different concepts were designed from architects, artists or engineers from all over the world. Some of them are realistic. Some of them are unrealistic ideas.
Real self-sufficient floating homes, used as permanent residences, are probably a novelty. Two Fraunhofer Institutes based in Dresden, the Fraunhofer Institute for Transportation and Infrastructure Systems (IVI) and the Fraunhofer Institute for Ceramic Technologies and Systems (IKTS), as well as other partners work together in the autartec® project. Their aim is to build a self-sufficient floating home on Lake Geierswalde, to the northwest of the city of Hoyerswerda (Germany) in the Lusatian Lake District, by 2017.
According to Fraunhofer, this floating home will not only look elegant. It will also be independent from external water sources as well as supply of energy like electricity and heat. “These kinds of energy self-sufficient floating homes do not exist yet,“ says autartec® project coordinator Professor Matthias Klingner of IVI. Many lakes in the Lusatian Lake District are cut off from infrastructure such as water and energy supply. “We want to find a solution for this kind of environment,“ says Klingner.
The self-sufficient house extends over two floors, offers 75 square meters of living space on the ground floor, and another 34 square meters on the first floor. A 15 square meter terrace overlooks the entire lake. It is based on a 13 by 13 meter steel pontoon. Solar cells will provide electricity. They are integrated in the building envelope. In order to save space, the rechargeable lithium polymer battery system are integrated into the textile concrete walls or into the stair elements.
Researchers at IVI develop an efficient heating and cooling systems. A salt hydrate fireplace provides heat on cold winter days. A tub, filled with water and salt hydrates, is placed above the fireplace. “When the fireplace is on, the salt hydrates liquefy and begin to absorb heat,“ Dr. Burkhard Fassauer of IKTS explains. The thermal energy can be stored almost indefinitely in case of completely liquefied salt hydrates. In order to release the heat when required, radio-based technology is used to induce crystallization. The principle is known from pocket warmers. A clicked metal disc inside induces crystallization so that the pocket warmer solidifies and gives off heat. When heated in water, the crystals liquefy and the heat is stored until the next click.
But a fireplace is not enough to ensure a comfortable air temperature during the winter. In this case, a zeolite thermal storage unit in the pontoon might help. The zeolite minerals are dried during the summer. This is a purely physical process in which heat is stored. “In winter, the moist air is enough for the storage unit to give off heat,“ Fassauer explains. An adiabatic cooling system provides cool air in the summer. It does not require electricity compared with conventional air conditioning systems. It can use the principle of evaporative humidification to cool. One surface on the side of the house is planted and moistened. The evaporation process will cool the building envelope.
The experts at IKTS are responsible for the water supply in the houseboat. “We are currently developing and experimenting with a closed loop system for drinking and service water,“ Fassauer explains. To accomplish this, the scientists rely on a combination of ceramic membranes and various electrochemical and photocatalytic processes. Land-based wastewater treatment is usually using biological processes. This is not possible in a floating house. “We must rely on physical and chemical methods. Thus, ceramics provide very efficient ways to bring together processes like photocatalysis, electrochemistry and filtration in a confined space,“ says Fassauer. Such processes are very aggressive. Other materials like steel and plastic will fail. The equipment for the circulatory system will be accommodated in the pontoon of the self-sufficient floating home.