The main subject of this study, that is part of the Adapt2change project, is the comparison between geothermal and conventional greenhouse production of tomato, pepper, eggplant and cucumber. More specifically this study includes weekly measurements in the geothermal and conventional greenhouse of the TEI of Thessaly to assess the water savings with the use of a hydroponic system. First of all, there is information about hydroponic systems, the technical characteristics and the advantages and disadvantages of them. In addition, there is information regarding greenhouses, their different types and the field of greenhouse cultivation in general, as well as the heating system, because very specific temperatures are needed to achieve efficient production. There is also a geothermal analysis with an explanation of geothermal energy, its application and the benefits and drawbacks of its use. Furthermore, information is provided about the heat pump device, which is utilized in the geothermal greenhouse, the technical characteristics and the pros and cons of its use. In this study, there is also an extended report of the characteristics of production, more specifically of tomatoes, peppers, eggplants and cucumbers. Finally, there are charts that present the results of every cultivation period, a comparison between the conventional and the geothermal greenhouse production and a conclusion about the hydroponic systems and geothermal energy use.