## 8 Conclusions
An example from the presented case study in this article is the introduced solar-combi system for the swimming pools heating and hot water production. Another feasible intervention could also be the introduction of the emerging technology of photovoltaic hybrid solar thermal panels, for the concurrent electricity and thermal energy production. Nevertheless, in the specific application, this option was impossible to be proposed, due to the siting of the photovoltaic panels on the roof of the main Stadium's stands. The installation of a new hydraulic network at this particular location, for the produced thermal energy transfer, would require extensive technical works with considerable additional set-up cost. On the contrary, as underlined above, all the proposed measures were formulated according to the existing technical infrastructure in the Stadium. In this way, it was also ensured that the realization of the proposed measures will cause the minimum possible impacts on the regular operation of the offered facilities. Indeed, apart from the openings' replacement, all the rest implied technical works are limited in specific points, either in outdoor space or in the existing boilers rooms. The article attempted to approach an integrated methodology for energy performance upgrade of large size Stadiums. This topic, as indicated in the introductory section, has not been covered in the existing scientific literature so far. The integrated approach is based on the investigation of all the possibly available measures that could be utilized for energy savings and production. The structure of the article indicates the proper order for the investigation and the dimensioning of the potential measures, starting from passive systems, moving to indoor space conditioning and thermal energy production active systems and ending with the lighting system and the rest consumptions. Once the potential energy saving measures have been investigated, the electricity production plants are examined and dimensioned on the basis of the remaining electricity consumption. The BEMS is designed lastly, in order to control and supervise the operation and the performance of all the introduced active systems. Another crucial point is the selection of the most appropriate active technologies for energy saving and production. In the specific case, for example, the availability of high solar radiation imposed the utilization of solar collectors and photovoltaic panels. The significant biomass potential in the island of Crete also led to the introduction of a biomass heater, while the considerable cooling loads and the vicinity of the Stadium with the coastline implied the installation of an open loop geothermal system. These systems constitute without doubt the optimum selection for this specific application. However, for a different facility at a different location, the above systems may not be applicable. The conclusion is that, in any case, the consultants should seek for the most economically and technically feasible interventions, imposed by the locally met conditions and, of course, the type and size of the existing energy loads. Generally, we could claim that the presented case study constitutes a representative application for the Mediterranean islands and for locations with similar climate conditions, significant biomass potential, perhaps from agricultural by-products, availability of aquifer, etc. Finally, the demonstrative attitude of the overall proposed project is of considerable importance too. Taking into account the number of daily users and visitors in the Stadium, the proposed project aims at the promotion of the rational use of energy concept, through the demonstration of the introduced measures. To this end, special actions have been also proposed, such as demonstrative screens located in strategically selected points along the Stadium presenting the current energy production and consumption and relevant statistical data, school or academic educational visits, etc.