## 4 Results  
### Improving the Energy Performance of the Outpatient Medical Center  
Once it was verified that the model satisfactorily estimates the building's electrical demand and computed the desirable indices, the passive and active substitution scenarios were analyzed in three lots: Lot A, corresponding to cases where there are exclusively passive modifications to the roof or wall; Lot B, where passive modifications to the roof are  
\begin{table}
\begin{tabular}{l c c c} \hline \hline
**Parameter** & **Value** & **Unit** & **Reference** \\ \hline Electricity price & 1.07 & MXN / MJ & [40] \\ Emission factor & 0.012 & kg CO\({}_{2}\)/ MJ & [41] \\ Electricity inflation rate & 4.0 & \% & [42] \\ Annual discount rate & 1.0–20.0 & \% & [43] \\ Maintenance annual & 6.0 & \% & [42] \\ increase rate & 15 & years & [31] \\ \hline \hline \end{tabular}
\end{table}
Table 6: Costs, energy, and environmental assumptions for performance indices of the medical center.  
combined with efficient air conditioning systems (inverters); and Lot C, where, in addition to the active and passive modifications, a reflective coating is added onto walls. Figure 8 illustrates the KPI results both monthly and annually for the three analyzed lots linked to electricity consumption.  
For the scenarios with modifications exclusively on the roof or wall (Figure 8a), only applied passive technologies are feasible to reduce the medical center energy consumption between 5% and 11% for the hottest months (April-September). Green roof was detected as the least effective (annual KPI of 96.3%), followed by polyurethane insulation (annual KPI of 94.3%). In the case of selective coating on the facade, during the hottest months, its contribution is almost zero; however, it demonstrates exemplary performance in energy saving for winter days. Furthermore, the annual advantages in energy savings are not negligible, decreasing by around 9% annually. For its part, the analysis of the annual KPI indicates that reflective coating on the roof (Case A-II) and its combination with expanded polyurethane (Case A-III) are the ones that have the most significant benefit for the building, reducing electrical demand by 10.09% and 10.19%, respectively. It is important to highlight that the contribution of including the expanded polyurethane layer can represent a higher cost when modifying the envelope with an almost zero energy benefit of 0.1% annually and barely 1% for the hot month of the year. It is also important to emphasize that although the lower consumption in the warmer months is obtained in Case A-III, the monthly curve of Case A-II is more constant throughout the year, obtaining even better energy benefits for the winter season (November to February).  
The scenarios in Lot B demonstrate the benefits of combining passive and active technologies. According to Figure 8b, the effect of passive technologies in the envelope is better appreciated when introducing inverter air conditioning systems. In summary, it is possible to reduce the electrical consumption of the outpatient medical center for the hottest months from 22% (Case B-I) to 31% (Case B-IV). Excluding Case B-I, which proposes using an inverter system without modifications to the envelope, again, selective coating on the walls (Case B-VI) and green roofs (Case B-V) have the least favorable results. At the same time, the reflective coating on the roof and its combination with insulating material were again the best thermal options, obtaining practically the same performances (KPI of 72.2% and 72.05%, respectively). The expanded polyurethane on the roof is benefits from using inverter technology, differing only 3.5% from the best Case. Finally, the results of Lot C (Figure 7c) show that the integration of selective coating on the walls improves the energy performance of the medical center by 2.45% concerning theirs homologous of the Lot B. The above implies that a white reflective coating provides the greatest thermo-energetic advantage to the envelope.