## 5 Discussion  
Each NN was trained based on the respective indoor sampled conditions of each office and its respective outdoor weather conditions, with an adequate margin of error. Each of the different trained networks had predicted indoor conditions as a function of the same outdoor weather (Figures 2 and 3) with the aim to demonstrate the effect of internal coverings over indoor ambiences, as in the laboratory analysis. Previous to this analysis, it is important to remember that, in previous works [1; 2], statistical studies showed that internal covering materials used in several offices such as paper, paint, and plastic, showed a statistical behavior representative of the permeable, semi-permeable, and impermeable \begin{table}
\begin{tabular}{c c} \hline
**Covering** & **Permeability (kg/(m s Pa))** \\ \hline Paper and Plaster & 1.44e-10 \\ Paint & 1.75e-12 \\ Plastic & 0.80e-12 \\ \hline \end{tabular}
\end{table} 
Table 2: Permeability values of different types of coverings [1; 2; 3; 4; 5]. Figure 11: Indoor air percentage of dissatisfied persons (PD\({}_{\text{IAQ}}\)) predicted for each internal covering during the summer season. Figure 12: Indoor air enthalpy predicted for each internal covering during the summer season. materials and, in consequence, the offices buildings with these materials were selected to model the behavior of internal covering materials. In accordance with the previous works performed in the summer season, for this climatic region, a more interesting period helps to appreciate the more intense effect of internal coverings. In this sense, we can appreciate that, during the winter (Figure 5), permeable coverings tended to exert an opposite effect on the outdoor conditions. In particular, the humidity cumulated and released from permeable materials is expected to be found in the first 4 h (from 19:30 to 11:30) and, after this, only permeable internal coverings will reduce partial vapor pressure more slowly than impermeable internal coverings. Additionally, the opposite effect was appreciated during the last hours of occupation in this season. This effect was more intense in the summer, as can be seen in Figure 9. As soon as the outdoor partial vapor pressure was reduced from an initial value of 19:12 to 0:00, the indoor partial vapor pressure in offices with permeable internal coverings released humidity and tended to increase its partial vapor pressure. Furthermore, the opposite effect to the increase in the outdoor partial vapor pressure can be appreciated during the last hours of the unoccupied period from 06:00 to 09.00. We can also see that, during the winter and summer seasons, the indoor ambiences of office buildings with impermeable internal coverings showed a tendency very similar to that of the outdoor ambiences. Finally, the office with semi-permeable materials tended to maintain a nearly constant partial vapor pressure during the night in both the seasons (cf. Figures 5 and 9). As a consequence of this effect of the internal covering over indoor ambiences, we can appreciate clear consequences to thermal comfort and energy saving. For instance, as seen in Figure 6, the acceptability index (\(\mathrm{ACC_{IAQ}}\)) during the winter showed a nearly constant value of 0.5, while the impermeable coverings showed a great variability of this index over time. This variability is a clear example of the effect of temperature and relative humidity over indoor partial vapor pressure in office buildings with impermeable coverings. As seen in Figure 10, this same index revealed higher acceptability during the summer season as a consequence of lower indoor partial vapor pressure during the first and last hours of the unoccupied period. Consequently, a better acceptability of indoor ambiences was expected when these materials (permeable coatings) were used. The same effect was identified via the expected number of people that were unsatisfied with the perception of indoor air quality, by means of the \(\mathrm{PD_{IAQ}}\) index (Figures 7 and 11).