**5. Conclusions**

The present research proposes a new methodology to predict the indoor ambience based on NNT procedure and using real-sampled data that would provide better insights to future research toward improving the system of predicting indoor ambiences and reaching a more detailed database of real material properties.

From this research, it can be concluded that it is possible to develop a predictive model of internal coverings' e ffect based on ANN and real-sampled data. This way, such a model becomes a useful tool to help predict the expected materials thermal behaviour. Furthermore, obtained ANN models showed that the control level of internal coverings is directly related to the vapor permeability, which is in clear agreemen<sup>t</sup> with previous statistical studies, thereby indicating the validity of this methodology.

In this case study, a common indoor partial vapor pressure model was obtained as a function of the permeability level of internal coverings and outdoor weather conditions during non-occupancy. Our results sugges<sup>t</sup> that, as a consequence of the long period of non-occupation, the average e ffect of moisture release of materials can be neglected, and the model can be identified as the first term of the moisture transfer equation.

Simultaneously, the second model that reflects the same indoor conditions during the occupancy period as a function of material permeability level and outdoor weather conditions can be represented by a nearly horizontal plane. In other words, during this period, as a consequence of the high number of air changes, the permeability e ffect of internal coverings does not exert any e ffect on the indoor conditions.

Furthermore, as an example of the predictive accuracy of the ANN, our results showed that, during the winter unoccupied period, permeable materials tended to increase the internal partial vapor pressure and, on the contrary, impermeable internal coverings demonstrated the opposite behaviour. These results are in clear agreemen<sup>t</sup> with the main results obtained in our earlier studies [6–10].

Finally, for future research, the authors plan to focus on developing systems to improve thermal comfort and optimize energy saving on an average and during peak conditions, especially during the first hours of occupation. Furthermore, in-detail analysis of a new internal coverings design criteria based on these results is warranted.

**Author Contributions:** Conceptualization, J.A.O.; Methodology, J.A.O., Á.M.C. and R.B.; Software, J.A.O.; Validation, D.V., Á.M.C. and R.B.; Formal Analysis, J.A.O., D.V., Á.M.C. and R.B.; Data Curation, J.A.O. and D.V.; Writing—Original Draft Preparation, J.A.O.; Writing—Review and Editing, J.A.O. and D.V.

**Funding:** This research was funded by CYPE Ingenieros S.A. in their research project to reduce energy consumption in buildings and its certification, in collaboration with the University of A Coruña (Spain) and the University of Porto (Portugal) (Grant No. 64900).

**Acknowledgments:** The authors wish to express their deepest gratitude to the Sustainability Specialization Campus of the University of A Coruña for the administrative and technical support.

**Conflicts of Interest:** The authors declare no conflict of interest.
