In this project, the benefits of the zero-energy buildings technologies and of the geothermal exploitation technologies on small communities or cities are evaluated. The public buildings can be the first application field of this procedure. The first step is the analytical energy audit of close-to-each-other public buildings in each country and the estimation of their energy efficiency, before any measure is applied. These audits will indicate the thermal needs of the buildings, before and after the application of energy saving technologies. In this phase, the geothermal potential of each will be evaluated, in order to investigate the possibility to replace the old heating systems with a geothermal-based heating system. At the next step, two studies will be developed: (a) The first will indicate which energy saving measures are more appropriate and efficient for each building and (b) the second one will include the location and capacity of geothermal-based units that can cover the thermal needs of the buildings in each country and the design of their heating system. The application studies and call for tender will be prepared following also green e-procurement procedures and aiming in building pilot but also expandable systems for the whole area, in regard with the geothermal potential exploitation. After the installation of the geothermal-based heating systems, a short period of technical evaluation will follow, using on-site measurements that will also be available on the web, proving the achieved energy saving and sustainability of the system.