## 4 Conclusions  
From the results deduced from the analysis, it was possible to evaluate how the energy consumption of public buildings should be reduced. The case study of the \"Ex Institute of Zoology\" has shown how it is possible to reduce the consumption of a historic university building without implementing interventions that affect its historicity. The method prepared in all its phases can be reproduced and adapted to redevelop the buildings that are part of the cultural heritage, considering the different architectural characteristics, construction materials, regulatory and historical constraints. A BIM modeling was performed to analyze the structure in all its components. Concurrently, a thermal transmittance study was performed to be used as a comparison and especially to be used in BIM modeling to have much more accurate data. The obtained values lead to significant energy savings of 35% on overall consumption; an 8% saving on consumption with the single intervention of replacing the fixtures, with new ones having thermal break glass and charged with argon gas; and a 20% saving by creating a new centralized system to replace the individual splits, the replacement of the light fixtures with LED lights and the installation of photovoltaic panels on the highest roofs of the building. Both the implementation of a single intervention and that of all the interventions may lead to a significant reduction in terms of CO\({}_{2}\) emissions (\(-\)33%). In conclusion, it is a duty for the administrations to evaluate solutions to make historical buildings more efficient to cope with the increases in bills by renovating \begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{4}{c}{**Total Consumption**} \\ \hline Total primary energy requirement & 508,440.61 & kWh \\ Thermal energy requirement for heating & 135,975.67 & kWh \\ Cooling thermal energy requirement & 40.784.00 & kWh \\ Domestic hot water thermal energy requirement & 732.38 & kWh \\ Electricity requirement for lighting & 28,198.40 & kWh \\ Design thermal load & 113,460.00 & kW \\ CO\({}_{2}\) emissions & 220,256.47 & kg/year \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Overall post-intervention needs of the Ex Institute of Zoology. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Post Intervention Requirement for Replacement of Thermal Break Glass with Argon Gas** \\ \hline Total primary energy requirement & 707,661.32 & kWh \\ Thermal energy requirement for heating & 140,356.07 & kWh \\ Cooling thermal energy requirement & 732.38 & kWh \\ Domestic hot water thermal energy requirement & 732.38 & kWh \\ Electricity requirement for lighting & 38,115.00 & kWh \\ Design thermal load & 141,355.00 & kW \\ CO\({}_{2}\) emissions & 306,558.00 & kg/year \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Thermal requirement after the replacement of thermal break glass with Argon gas in the Ex Zoological Institute. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Post-Intervention Requirement for the Construction of a Photovoltaic System, LED Lights** & **and Creation of a Centralized System** & \\ \hline Total primary energy requirement & 603,747.60 & kWh \\ Thermal energy requirement for heating & 133,294.70 & kWh \\ Cooling thermal energy requirement & 64,972.31 & kWh \\ Domestic hot water thermal energy requirement & 732.38 & kWh \\ Electricity requirement for lighting & 28,198.40 & kWh \\ Design thermal load & 151,664.00 & kW \\ CO\({}_{2}\) emissions & 261,543.40 & kg/year \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Post-intervention requirement for the construction of a photovoltaic system, LED lights and construction of a centralized system for the Ex Institute of Zoology. public structures in conditions of degradation. This paper could be considered a guideline to be followed to achieve this goal. Conceptualization, M.M. and D.M. ; methodology A.G., M.M. and D.M. ; software, A.G. and M.M. ; validation, D.C., A.G., V.F. and D.M. ; formal analysis, M.M. ; investigation, M.M. ; resources, V.F., A.G. and D.M.