## 3 Results and Discussion
### PCM-Incorporated Building Model
#### 3.2.1 Optimal Melting Point  
The simulation results for the comparison of heating and cooling loads between the baseline building model, featuring extruded polystyrene insulation, and PCM-incorporated building models with varied phase transition temperatures reveal substantial energy-saving potential. For the PCM with a melting point of 21 \({}^{\circ}\)C, heating and cooling loads experienced  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Amman** & **Irbid** & **Aqaba** & **Oradea** \\ \hline
**Baseline Building Model** & \multicolumn{4}{c}{**Energy Use Intensity [kWh/m\({}^{2}\)/Year]**} \\ \hline Energy Intensity per Conditioned Floor Area & 147.03 & 155.08 & 143.09 & 181.40 \\ \hline Energy Intensity per Total Floor Area & 132.10 & 139.33 & 128.55 & 162.97 \\ \hline HVAC Energy Intensity per Conditioned Floor Area & 91.14 & 99.19 & 87.20 & 123.66 \\ \hline HVAC Energy Intensity per Total Floor Area & 81.89 & 89.12 & 78.34 & 111.10 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Energy use intensity (EUI) for the baseline building model in Amman, Irbid, Aqaba, and Oradea.  
reductions of 31.30% and 18.22%, respectively. At a melting point of 23 \({}^{\circ}\)C, the reductions were 34.38% for heating and 23.33% for cooling. Similarly, for the PCM with a melting point of 25 \({}^{\circ}\)C, reductions were 31.56% for heating and 17.06% for cooling. The PCM with a melting point of 27 \({}^{\circ}\)C demonstrated reductions of 24.90% for heating and 11.44% for cooling. Lastly, the PCM with a melting point of 29 \({}^{\circ}\)C resulted in an 11.75% reduction for heating and a 4.91% reduction for cooling. Overall, incorporating PCMs into building envelopes exhibits a consistent trend of significant reductions in both heating and cooling loads across different melting points, highlighting the potential for substantial energy savings.  
As directly observed from the simulation results, the PCM with a phase transition temperature of 23 \({}^{\circ}\)C reached the highest energy-saving rate compared with the baseline simulation results and the other melting points. As illustrated in Figure 18, the total energy-saving rate achieved by incorporating PCM with a melting point 23 \({}^{\circ}\)C is 18.23%, compared with the energy-saving rates of 15.76%, 15.53%, 11.69%, and 5.38% for melting points of 21 \({}^{\circ}\)C, 25 \({}^{\circ}\)C, 27 \({}^{\circ}\)C, and 29 \({}^{\circ}\)C, respectively.  
Figure 19 shows an HVAC energy comparison chart for the different melting points of PCM. It is worth mentioning that since the indoor set point temperature for the HVAC system used in the energy simulation of the building was 23 \({}^{\circ}\)C, these results comply with the literature [38; 45], as they proved that the optimal PCM melting point should be close to the indoor set point of the HVAC system.  
Another observation was noticed from the energy simulation results; PCMs can perform better in reducing the heating load more than the cooling load. For the PCM with a melting point of 23 \({}^{\circ}\)C as an example, the energy-saving rate for heating is \(-\)34.38%, while for cooling, the energy-saving rate is \(-\)23.33%. This might be caused by the fact that in Jordan, the daily temperature fluctuation during the winter season is higher than that in summer, resulting in a higher effect of the latent heat of fusion for these materials.  
Figure 18: Annual electrical energy consumption chart for PCM-incorporated building with melting point 23 \({}^{\circ}\)C compared with the baseline building model.