## 8 Conclusions  
This article presents the overall roadmap towards the energy performance upgrade of a national stadium. The size of the Stadium's facilities and the variety of the energy loads make the overall work a complex and demanding task. Aiming to summarize the quantitative results of this work, we may conclude to the following remarks:  
* High energy saving percentages are achieved by each one of the proposed interventions. Specifically, the combined replacement of particularly selected openings in the Stadium's envelope and the geothermal system installation lead to 48% electricity savings for the indoor space conditioning, compared to the existing operation. Moreover, a total savings of 83% is also achieved on the primary energy consumption for hot water production and swimming pools heating. The introduced interventions on lighting system will also offer 52% savings on the electricity consumed for the Stadium's lighting needs. The reduction percentage on the reactive electricity annual consumption, due to active electricity savings, exceeds 42%. * The Stadium's energy performance is upgraded to rank A+ from rank D. With further production of 199,475 kWh of electricity, which can be achieved with the additional installation of roughly 85 kWp of PV panels, the Stadium will be upgraded to a zero-energy infrastructure. * The electricity and diesel oil annual achieved savings impose a corresponding annual CO2 emission reduction above 85%, with regard to the current operation. \begin{table}
\begin{tabular}{c c} \hline
**Production Technology** & **Primary Energy Production (kWh)** \\ \hline Photovoltaic station & 2,704,862 \\ Biomass & 180,691 \\ Solar collectors & 305,394 \\ Total production & 3,190,947 \\ Annual primary energy consumption & 3,882,875 \\ R.E.S. annual penetration percentage (\%): & 82.18 \\ \hline \end{tabular}
\end{table} 
Table 11: R.E.S. production annual penetration percentage calculation. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Existing Operation**} & \multicolumn{2}{c}{**New Operation**} & \multicolumn{2}{c}{**CO2 Saving**} \\ \cline{2-7}
**Energy Source** & \begin{tabular}{c} **Primary Energy** \\ **Consumption** \\ **(kWh)** \\ \end{tabular} & \begin{tabular}{c} **CO2** \\ **Emissions** \\ **(m)** \\ \end{tabular} & \begin{tabular}{c} **Primary Energy** \\ **Consumption** \\ **(kWh)** \\ \end{tabular} & \begin{tabular}{c} **CO2** \\ **Emissions** \\ **(tn)** \\ \end{tabular} & \
\begin{tabular}{c} **(tn)** \\ \end{tabular} &
\begin{tabular}{c} **(\%)** \\ \end{tabular} \\ \hline Active electricity consumption & 5,478,674 & 5418 & 346,478 & 343 & 5076 & 93.68 \\ Reactive electricity consumption & 1,126,380 & 1114 & 650,844 & 644 & 470 & 42.22 \\ Total electricity consumption & 6,605,055 & 6532 & 997,322 & 986 & 5546 & 84.90 \\ Oil diesel consumption & 186,059 & 184 & 0 & 184 & 184 & 100.00 \\ Totals & 6,791,114 & 6716 & 997,322 & 986 & 5730 & 85.31 \\ \hline \hline \end{tabular}
\end{table} 
Table 12: Analysis of the annual reduction on the CO2 emission. * Impressive evaluation indices are calculated, like the remarkably low payback period (12 years), the high R.E.S. annual penetration percentage (82%) and the high energy saving percentage (83%). Beyond the above presented quantitative results, the article highlights the significant energy saving potential on large size sports facilities, such as national Stadiums. As a matter of fact, such large size facilities exhibit considerably high energy consumptions, through a variety of final energy uses, with lighting, indoor space conditioning, hot water production and swimming pools heating being the most important. The size and the variety of these loads create a huge potential for the introduction of active and passive energy performance upgrade measures, offering also the chance for the configuration of advanced systems, through the combined operation of fundamental technologies.