## 3 Results and Discussion
### PCM-Incorporated Building Model
#### 3.2.4 Optimal PCM Panel Thickness  
Finding the optimal thickness for the PCM layer inside the external wall includes investigating the external wall with different PCM panel thicknesses, particularly 11.2 mm, 20.8 mm, and 37.1 mm, while fixing all other measures to focus on finding the optimal thickness of the incorporated PCM panel that will achieve the best results for the specific application. In evaluating the impact of different thicknesses of a single sheet of BioPCM(r) on the baseline building model with extruded polystyrene, the findings highlight the significance of PCM thickness in achieving optimal energy-saving results.  
The results indicate that increasing the thickness of the incorporated BioPCM(r) panel contributes to greater reductions in electrical energy consumption. For a thickness of 11.2 mm, the PCM-incorporated building model demonstrated a 28.50% reduction in heating and a 14.28% reduction in cooling, resulting in a total end-use energy reduction of 13.71%. A thickness of 20.8 mm led to more substantial reductions, with a 31.93% decrease in heating and a 19.19% decrease in cooling, contributing to a 16.25% total end-use energy reduction. Further increasing the thickness to 37.1 mm resulted in even greater reductions, with a notable 38.79% decrease in heating and a 24.76% decrease in cooling, achieving a  
Figure 20: HVAC energy comparison chart for the tested PCM products.  
significant 20.14% total end-use energy reduction, as shown in Figure 23. Figure 24 shows an HVAC energy comparison chart for the tested PCM layer thicknesses.  
Simulation results revealed that the highest energy-saving rate was achieved in Amman (20.14%), followed by Irbid (19.78%), Aqaba (7.50%), and Oradea (5.64).  
These results comply with the fact that PCMs can perform better in moderate climate conditions, like in Amman and Irbid, significantly more than their performance in very hot-dry climate conditions like in Aqaba city and cold-wet climate conditions like in Oradea  
Figure 21: Annual electrical energy consumption chart for the building incorporated with BioPCM® layer closer to the interior surface of the external wall compared with the baseline model.  
Figure 22: HVAC energy comparison chart for the tested PCM configurations.  
city. This is due to the fact that average daily temperatures are closer to the PCM phase transition temperature of 23 \({}^{\circ}\)C. This proximity facilitates a greater latent heat of the fusion effect, stabilizing building temperatures and reducing HVAC system energy usage for indoor climate control. Furthermore, the energy use intensity (EUI) of PCM-incorporated buildings was notably lower than that of baseline models with conventional insulation in all locations, demonstrating a substantial reduction in total end-use energy. Table 7 compares the EUI and HVAC electricity intensity for PCM-incorporated and baseline building models in Amman, Irbid, Aqaba, and Oradea.  
Figure 23: Annual electrical energy consumption chart for the building incorporated with 37.10 mm layer thickness of BioPCM® M91/Q23 compared with the baseline model.  
Figure 24: HVAC energy comparison chart for the tested PCM layer thicknesses.  
As illustrated in Table 7, a considerable reduction in the EUI could be achieved by incorporating PCM in the building envelope. Moreover, in Amman, as demonstrated in Table 7, the EUI value for the building after incorporating PCM with optimal specifications and properties could reach 117.42 kWh/m\({}^{2}\)/year, which is close enough to the average ideal value for green buildings of 115.14 kWh/m\({}^{2}\)/year stated by the Building Energy Efficiency Standard (BEES).