Energy fence
An energy fence , also called a fence collector or (thermal) solar fence , is an above-ground heat exchanger (collector) in a heat pump heating system . The collector, which looks like a woven fence, absorbs heat from the environment (air / wind, rain, ...) and solar radiation and feeds it to the evaporator in the brine circuit of the heat pump .
Often the above-ground collector is combined with an underground collector so that the ground can be used as an additional heat source and storage.
history
Energy fences and other above-ground collectors in various forms (energy cones, energy stacks, ...) were already developed in the 1980s. Since then, the design, materials and system structure have been continuously developed, but the basic principle has remained unchanged.
functionality
fence
The fence consists of black corrugated pipes made of UV- resistant, flexible plastic that run on top of one another and are led past posts alternately like a wicker fence. This ensures a safe stand and at the same time absorbs thermal expansion due to different temperatures.
A frost-proof water-brine mixture flows through the pipes, which acts as a heat transfer medium. The collector removes the convection heat from the air, wind and rain and, if necessary, the condensation heat of the air humidity when the dew point is not reached. In addition , due to its black color , the energy fence also absorbs direct radiation from the sun, similar to a solar collector . The annual performance factor (JAZ) is therefore normally higher than that of a pure air / water heat pump.
Due to its similarity to "real" fences , an energy fence can not only act as a heat collector, placed on the edge of the garden as a property boundary, but also serve as an enclosure and thus fulfills a double function.
The fence can be planted to create a natural look. In particular, various climbing plants come into question , but when making the selection, make sure that the plants used are insensitive to the cold temperatures near the fence. Furthermore, the foliage should not be too dense, otherwise the effectiveness of the solar heat utilization will suffer due to the shading. A compromise between appearance and effectiveness are deciduous plants that shed their leaves in winter, i.e. during the heating season when the heat is primarily needed. For example, certain deciduous, hardy vine tendrils have proven their worth .
Geothermal collector (optional addition)
To use synergies between ambient / solar heat and geothermal energy , energy fences are rarely used alone, but mostly in combination with an underground collector. On the one hand, the ground serves as a heat source for cold days without sunshine or cold nights, since the energy fence hardly absorbs heat under these conditions. The ground collector then takes over the full energy supply of the heat pump. The geothermal collector increases the annual coefficient of performance of the heat pump compared to a version with a purely above-ground collector. On the other hand, the ground serves as a buffer heat store , which is regenerated (charged) on warm and sunny days when the energy fence supplies excess heat. This stored heat can then be called up again later in pure geothermal operation. Due to the heat storage, a combined fence / earth collector achieves a similarly good overall effectiveness as a pure earth collector despite its smaller area.
Technically, all types of construction are possible for the geothermal collector (surface collector, deep borehole probes, spirals, baskets, ...). In order to minimize the civil engineering work (see below), however, a linear form that runs underground parallel to the fence, for example as a trench collector, is most suitable . In its simplest form, the fence is simply buried partially (about a third) in the ground and thus acts both above and below ground.
Advantages and disadvantages
Compared to competing heating systems, heat pump systems with fence collectors, especially when supplemented with a geothermal collector, have a number of advantages and disadvantages:
Compared to conventional heating systems, especially those based on fossil fuels , energy fences have the advantage that renewable energy is used efficiently. The heating is therefore more sustainable and environmentally friendly. The additional costs for the installation are moderate; in return, savings in operating costs can be achieved.
Compared to pure geothermal heat pump systems, fence collectors have the advantage that they are less complex to install, but still achieve only slightly lower annual performance factors, especially in combination with a geothermal collector. Even with a supplementary geothermal collector in linear form (trench collector), the scope of earthworks is comparatively small, and there is no need for expensive deep drilling. As a rule, no building permit is required. Because of its compact design, the energy fence can also be used on small building plots. When renovating buildings and modernizing the heating system, an energy fence can also be integrated into an existing garden landscape at a later date with little effort.
Compared to pure air heat pump systems, systems with fence collectors have a higher annual coefficient of performance with moderate additional investment costs and, in combination with a geothermal collector, are able to provide heat all year round without additional electrical heating. In addition, fence collectors are noiseless.
advancement
As part of a solar and / or heat pump heating system, energy fences are financially supported by various public funding programs for energy saving and renewable energies. In Germany, the funding programs of the KfW banking group and the Federal Office of Economics and Export Control (BAFA) should be mentioned in particular . There are also various programs in the federal states and down to the municipal level.
Individual evidence
- ↑ Klaus-Dieter Kaufmann: Energy roofs, energy facades, energy fences, energy stacks and other energy absorbers: a practical guide for homeowners, builders and heating specialists with a comprehensive overview of the market . Idea-Verlag, 1981, ISBN 3-9800371-3-4 .
- ↑ a b Brine-to-water heat pump with energy fence. Energy Solutions, accessed October 17, 2011 .
- ↑ a b Heat source energy fence: an alternative to deep drilling. MH-Anlagentechnik, Berlin, accessed on October 17, 2011 .
- ↑ Helmut Weik: Expert Practice Lexicon Solar Energy and Solar Techniques: 1880 Terms from A – Z for understanding solar techniques and for using solar energy for environmentally friendly energy supply . 2nd Edition. expert, 2006, ISBN 3-8169-2538-3 .
- ↑ Thomas Laasch, Erhard Laasch: House technology: Basics - planning - execution . 11th edition. Vieweg + Teubner, 2005, ISBN 3-519-25265-1 , pp. 707 ( limited preview in Google Book search).
- ↑ Fence as an energy store . In: House + Energy . May June. Photon Europe, 2009, ISSN 1860-9015 ( full text hausundenergie.de [PDF]).
- ↑ More than just a property boundary: the energy fence. (No longer available online.) Hausgarten.net, archived from the original on September 26, 2012 ; Retrieved October 18, 2011 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Ernst G. Brehmer, Heinz-W. Beckmann: Reducing construction costs: savings concepts for building owners . 5th edition. Vieweg + Teubner, 2000, ISBN 3-528-48838-7 ( limited preview in the Google book search).
- ↑ Thomas Königstein: Advice on energy-saving building: In a nutshell: neutral specialist information for more energy efficiency . 4th edition. Fraunhofer-IRB-Verlag, 2009, ISBN 978-3-8167-7925-4 .
- ↑ Viktor Wesselak , Thomas Schabbach: Regenerative Energy Technology . Springer, 2009, ISBN 978-3-540-95881-9 ( limited preview in Google book search).
- ↑ Brine-water heat pump with energy fence , energiesparen-im-haushalt.de, accessed on October 18, 2011.
- ↑ Amortization calculation ( Memento of the original dated September 7, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 1.4 MB)
- ↑ Funding with the Kfw banking group
- ↑ Funding according to Bafa for solar collector systems ( memento of the original from March 14, 2018 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 39 kB)
