I. GEOTHERMAL PROBES are the most used geothermal systems – the primary source of ground to water heat pumps. They drill at depths of 50-200 m and geothermal wells (PEHA or PE-Xa pipe diameter 32-40 mm) are inserted into the drilling. Geothermal probes provide thermal transfer with closed loop soil through which ethylene glycol circulates with a freezing temperature down to -15 ° C.

Mounting of geothermal probes  in the drilling

Design of a  1.000 geothermal probes field – Institutul ELI-NP  Magurele

II. ENERGY PILES  – the piless with a structural role for a building become energy piles if it is mounted on their metalic structure PEHA or PE-Xa pipe with  16-32 mm diameter. Energy piles will be used as the primary circuit of the brine to water heat pumps that heat cool the building for which they were designed. Within the GABI Cost project, both the theoretical considerations and the monitoring of the advantages / disadvantages of the 3 solutions, both in terms of energy performance and the geotechnical performance of the energy pilots, have been studied.
• Use soil as a heat exchanger and energy storage environment;
• Add to their structural role of foundation pilots the role of geothermal heating and cooling elements ;
• The role of the fluid flowing inside the pipes is to transfer the heat of the soil to the primary circuit of the heat pumps;
• PEHA or PE-Xa pipes 16-32 mm in diameter are mounted on the W, UU or spiral-shaped armature.
– Heat extraction only – with heat pump (40-60 W / m; TEP = 2-15 ° C)
– Extraction and heat injection – with reversible heat pump (50-100 W / 25-35 ° C)
– Pipe configuration mainly characterizes both the energy performance and the geotechnical performance of the energy pilots;
– Designing the foundation on pilots is also essential for both energy performance and geotechnical performance of power pilots;
– The mass flow of the fluid flowing in the pipe significantly influences only the energy performance. – Variation of liquid velocity appears to be a more efficient solution than changing the diameter of the pipeline – to modify the flow rate: an increase in fluid velocity:
• from 0.2 to 0.5 m / s => increase in heat transfer rate of 7%
• from 0.2 to 1 m / s => increase in heat transfer rate of 11%.

Work in progress – UPU – Emergency Department Hospital Oradea: Heat pumps with 320 energy piles 

 Mount one of the  320 energy piles at the project: UPU – Emergency Department Hospital Oradea

 Kesz work in progress –  office building Cluj with 76 energy piles

House – heated and cooled with 10 energy piles

Beam founding and collecting pipes from geothermal piles


the diaphragm walls are designed with a structural design to protect the construction of a building by stabilizing the adjacent terrain. If the PEHA or PE-Xa pipe diameter 16-32 mm is mounted in the diaphragm walls, they become geothermal structures – the primary circuit of the brine to water heat pumps and the heat exchanger with the soil that reaches the storage medium. These geothermal structures will be used to operate the heat pumps that provide heating – cooling of the building for which they were designed.

Heat pumps on slurry walls –  Oromolu Building / Piata Victoriei  Bucharest

IV. TUNNELS  – like the diaphragm walls, if in the tunnel walls (underground trains, underground passages, …), PEHA or PE-Xa pipe diameter of 16-32 mm is mounted on the reinforcement, they become geothermal structures – primary circuit of the brine to water heat pumps and heat exchanger with the soil. These geothermal structures will be used to operate heat pumps that provide heating – cooling of neighboring buildings, train stations, ….


  • Geothermal energy obtained from geothermal structures is an ecological technology, a solution for heating and cooling buildings with a significant reduction in CO₂ emissions and other greenhouse gas emissions;
  • Ensure energy efficiency at the building level at the neighborhood / hour level, responding to the concept of sustainable city / town;
  • It is complementary to any other renewable energy system being a local source of renewable energy (the natural heat present in the earth);
  • No additional drilling is required, but minor changes in the design of the foundation and additional minimum installation costs;
  • The use of geothermal structures ensures localization of the surrounding area that can be used for further expansions;
  • The concept of geothermal energy can be adapted to spatial urban planning for cities of different sizes, with a different population density;
  • Energy pilots form a large thermal battery (similar to night-storage heaters): they heat the soil during the summer to improve winter heating and cooling during the winter to increase cooling during the summer period by providing a storage system the energy otherwise difficult to achieve;
  • Design of energy geostructures should be integrated into the design of conventional geotechnical structures through multidisciplinary real collaboration in all phases of the project. Geothermal analysis should be treated simultaneously with geotechnical issues in interaction with energy demand assessment. In the process, system interfaces must be handled with care.