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Energy efficiency in practice

Seasonal ground-source probe heat storage supports Germany’s biggest thermal solar installation

In the newly created district of Hirtenwiesen in the west of Crailsheim, the focus was on private homeowners independently generating a proportion of their heat requirement by the use of renewable energies or purchasing their requirement from a local or district heating grid. Thus, Crailsheim public utilities ensured a combination of modern family-friendly housing with green living: the supply of thermal heat and hot water has been based on the innovative use of renewable energies rather than on fossil fuels and, with a collector area of around 10,000 square metres, the largest thermal solar plant in Germany has been set up.

7,500 square metres of this can be found solely on the southern edge of a 15-metre high noise protection barrier, which makes the greatest contribution to the solar heat supply to around 2,000 residents. Nonetheless, what primarily focuses the plant technology on the future is the fact that the solar technology has been combined with an outstanding, seasonal ground-source probe heat storage system.

Efficient function of the ground-source heat storage system

The heated water from the collectors is initially transported to a buffer tank with a capacity of 480 cubic metres. The largest ground-source probe heat storage in Germany to date has been set up for the intermediate storage of the solar heat gained in the summer months, with which the residential buildings are heated in the winter:

- 80 RAUGEO ground-source probes at a depth of 55 metres
- PE-Xa probes in cross-linked polyethylene
- Best thermal and mechanical capacity with PE-Xa
- Temperature resistance of up to 75°C
- Insulation with foam glass gravel

Ultra-safe ground-source probes

For maximum safety requirements, both in introduction into the borehole and in long-term operation, REHAU supplies the RAUGEO PE-Xa probe with a unique 10-year guarantee. The distinguishing feature of this double U-probe is that it emerges as the only ground-source probe complete with no welded joints at the probe tip. The feed and return of the RAUGEO PE-Xa probe consist of one complete line, moulded into the probe foot in glass fibre reinforced polyester resin for maximum reliability.

Summary of the advantages of the REHAU ground-source systems:

RAUGEO PE-Xa probe is the only probe on the market with no welded joints
Heat storage possible up to 95°C
Also available as ground-source collector, energy pile and helix probe systems
10-year manufacturer’s guarantee

Distinguished as a lighthouse project

The solar plant in Hirtenwiesen generates three million kilowatt hours of thermal energy per year. The solar-based heat supply from Crailsheim public utilities reduces by half the demand for fossil fuels and saves the environment 1,000 tonnes of carbon dioxide per year.

For this, in the largest thermal solar plant in Germany, Crailsheim public utilities were awarded the title of “lighthouse project” by “Impulskreis Energie“. The group, which was set up by the German federal government, awards prizes to particularly innovative, environmentally friendly and forward-looking projects

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