From 30 June to 5 July 2025, GeoZS, the Faculty of Natural Sciences and Engineering of the University of Ljubljana, the Slovenian Civil Engineering and Building Institute and the Faculty of Civil Engineering, Transport Engineering and Architecture of the University of Maribor and the COST partnership of the FOLIAGE project organised the 3rd International Geothermal Summer School in Ljubljana. Under the title "Coupling and integration of energy piles with other geothermal technologies" we presented the latest shallow geothermal energy projects to 21 participants and 11 speakers from a total of 12 countries. The interdisciplinary collaboration brought together environmental sciences, geosciences, mechanical engineering, geomechanics and energy engineering.

The participants visited successful examples of Slovenian knowledge and practise: the production of heat pumps at KRONOTERM d.o.o., the Entrepreneurial Education Centre of the Velenje School Centre, the Katapult Entrepreneurial Center, and the high-tech company DEWESoft d.o.o., which has built the first seasonal underground geoprobe thermal storage (BTES) in Slovenia. We also visited the Šmarješke Toplice thermal spa, where thermal water is used for direct heating.

Eleven speakers from six countries took part in the school:

• Prof. Dr. Mihael Brenčič (NTF UL, Slovenia),
• Nina Rman and Dušan Rajver (GeoZS, Slovenia),
• Dr Hrvoje Dorotić (Hrvoje Požar Energy Institute, Croatia),
• Prof. Dr. Rao Martand Singh (Norwegian University of Science and Technology, Norway),
• Fiona M. Chapman (Institut national de la recherche scientifique, Canada),
• Assoc. Prof. Dr. Primož Jelušič (FGPA UM, Slovenia),
• doc. dr. Stanislav Lenart (ZAG, Slovenia),
• Prof. Dr Nikolas Makasis (University of Surrey, UK),
• Grzegorz Ryżyński (National Geological Institute, Poland).

The Summer School was supported through several projects. Project CA21156 European network for FOstering Large-scale ImplementAtion of energy GEostructure (FOLIAGE) has secured funding from Horizon 2020 and COST - European Cooperation in Science and Technology. Part of the activities were supported by ARIS-funded research programms at GeoZS and ZAG.

Proceedings of the 3rd International Geothermal Summer School Student Conference are available at here.

Support was also provided by:

• Ministry of the Environment, Climate and Energy,
• ARIS postdoctoral project TopDISPERZ,
• INRIGeoTeam and Geo-OPT, co-funded by ARIS under the GeoZS development pillar,
• CRP GeoCOOL-FOOD project, co-funded by the Ministry of Agriculture and Rural Development and ARIS,
• and donors Atlas Trading d.o.o., DEWESoft d.o.o., KRONOTERM d.o.o., Radenska d.o.o. and Terme Krka - Šmarješke Toplice.