## 5 Conclusions  
This study has been developed to investigate a feasible solution to host an electrical power transformer enclosure inside a historical building with a reuse intervention. The site selected is made of a single room and it is supposed to have been built during the 3 rd century A.D. Its preservation is of fundamental importance, and the requirements for such installation are clear; the indoor microclimatic conditions shall not be modified, to avoid the formation of molds or saline formations over the plasters. High temperatures combined with high thermal gradients can cause the detachment of plaster. At the same time, the transformer enclosure's transformers must work at low temperatures, to avoid damage and malfunctions.  
The impact of the transformer enclosure on the microclimatic indoor parameters was therefore studied by CFD simulations, with five different simulations and two different layouts of the transformer enclosure. The simulations were validated using data obtained from a measurement field campaign performed during summer, from July to September. As hypotheses for the simulations were formulated, the worst-case conditions were recorded during the campaign (36.7 \({}^{\circ}\)C of air temperature and a humidity of 48.7% RH). The inlet air flow rate varied from 1100 and 2200 m\({}^{3}\)/h. In this work, only the minimum and maximum flow rates are discussed, leaving the other cases (1650 m\({}^{3}\)/h and 1925 m\({}^{3}\)/h) in the ESM document. The two layouts use the same boundary conditions but differ in the presence of a confining box containing the power transformer in the second case. The box is made of rigid foam insulation panels with a thickness of 8.0 cm and is designed to protect the building from the thermal stress caused by the rise in temperature due to the transformer power dissipating into the environment. Both layouts use an inlet fan to cool the transformer, but in the second case, the ventilation is directed inside the box by a duct system.  
The results showed good performances for the confined solution, which can maintain indoor temperature and humidity in an acceptable range for both the historical building and the power transformer, while the open layout is unable to maintain a good condition for both the maximum and minimum air-flow rates. Moreover, in the first layout, the simulated microclimatic conditions do not ensure the proper preservation of the building. The humidity notably decreases as the temperature rises compared to the external air temperature.  
In conclusion, this study aims to present a specific case where an electrical transformer enclosure is installed inside a historical building. From the analysis, to ensure the preservation of the building as well as the performance of the electrical transformer enclosure, confinement appears to be the best solution so as not to alter the internal microclimate conditions.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app142310827/s1](https://www.mdpi.com/article/10.3390/app142310827/s1)]([https://www.mdpi.com/article/10.3390/app142310827/s1](https://www.mdpi.com/article/10.3390/app142310827/s1)), File S1: Electronic Supplementary Material (ESM).  
Conceptualization, F.N. and L.G.; Data curation, L.G.; Formal analysis, F.N. and L.P.; Funding acquisition, F.N. and L.G.; Investigation, F.N., L.G. and L.P. Methodology, F.N., L.G. and L.P.; Project administration, F.N., L.G. and F.C.; Resources, L.G.; Software, F.N. and L.P.; Supervision, F.N., L.G. and F.C.; Validation, F.N., L.G. and L.P.; Visualization, F.N., L.G., L.P. and F.C.; Writing--original draft, F.N., L.G. and L.P. Writing--review and editing, F.N. and L.P. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author.  
The authors declare no conflicts of interest.