COP5+ - Further development of a heat- and cooling system with seasonal heat storage at the example of Central Europe´s biggest geothermal depth drilling field

Status

completed

Summary

The aim was to increase the overall energy efficiency of Plus-Energy-Houses by making the heat excess of summer available for use in winter. This is carried out by improvements of the technology seasonal heat storage to an intelligent overall system. With the construction of a research and development center of Fronius International GesmbH in Thalheim near Wels, the biggest geothermal depth drilling field in Central Europe has been established. From this a series of measurements is taken over 36 months, which have then been evaluated and analyzed. The findings of this project provide a basis for further developments of such systems.

Because of the storage of the summertime heat, the temperature of the soil surrounding the depths drillings increases. By optimizing the charging and discharging processes the losses are minimized. By raising the temperature of the heat source in combination with optimized building service management system, the COP of the heat pump during the heating period can be increased. A possible COP over 5 is expected. Furthermore, such a system offers the energetic ideal possibility of cooling in summer. This causes a remarkable decrease of power requirement which in return means a reduction of primary energy requirement.

The conclusions help to successfully realize more of such storage systems. By using such equipment’s the energy requirement of heating and cooling systems can be lowered and the overall energy efficiency of Plus-Energy-Buildings can be increased.

The developed calculation model for ground source heat exchangers was successfully validated by the obtained measurement data series. Few optimization measures could be developed at several points of the parameters of the control strategy and the system configurations. Following the optimization of the system configuration, a significant increase in energy efficiency could be achieved. The coefficient of performance could be raised of 4.5 to an average of about 6.5. This represents an improvement of over 40%. Based on these results, it is expected that an annual COP in the range of about 6.0 is reached with the installed heat pump system.

Project management

Fronius International GmbH
Ing. Josef Feichtinger

Project or cooperation partner

• ENERTEC Naftz & Partner OG
• Schöberl & Pöll OEG
• Vienna University of Technology – Institute of Building Construction and Technology – Research Center for Building Physics and Sound Protection

Fronius International GmbH
Ing. Josef Feichtinger
Günter Fronius Straße 1
4600 Thalheim
Tel.: +43 (7242) 241-2330
Fax: +43 (7242) 241-952330
E-Mail: feichtinger.josef@fronius.com