## 3 Results and Discussion
Zone III and Zone II show similar patterns with high CO2 improvements and significant cost reductions. Zone I has the lowest improvements in CO2 emissions, and again, a deterioration is observed in cost. Across all optimization objectives, Zone IV consistently shows the highest percentage improvements in both cost and CO2 emissions, indicating the effectiveness of optimization strategies in this zone. Zones II and III also perform well, with significant gains in CO2 emissions, though slightly lower than Zone IV. When the analyses are conducted based on the optimum CO2 scenario, a deterioration in costs is observed in all Zones except Zone IV. The findings suggest that climate zone-specific strategies may be necessary to maximize benefits, especially for relatively warm zones like Zone IV, which shows the most significant potential for improvement. Figure 12 illustrates the variation in cost components for different insulation thicknesses in the hottest (Zone I) and coldest (Zone IV) climate zones. In Zone I, the heating cost (\(C_{heat}\)) is initially significant but gradually decreases as insulation thickness increases, reflecting reduced energy consumption for heating. The cooling cost (\(C_{cool}\)) is relatively high at lower insulation thicknesses and shows a slight decrease as insulation thickness increases, indicating reduced energy use for cooling. The heating cost (\(C_{heat}\)) is significantly higher in the coldest zone compared to the hottest zone, especially at lower insulation thicknesses. This cost decreases substantially as insulation thickness increases, demonstrating the effectiveness of insulation in reducing heating demand. In Zone IV, the cooling cost (\(C_{cool}\)) is relatively lower due to the colder climate, and it shows minimal change with increasing insulation thickness. The overall pattern indicates that when increasing the insulation thickness, significant savings in heating costs can be achieved in colder climates, making it a cost-effective strategy. Figure 12 highlights the trade-off between the initial costs of insulation, plaster, and wall materials and the savings in heating and cooling costs achieved with increased insulation thickness. In Zone I, cooling cost savings are more pronounced, while in Zone IV, heating cost savings are more significant. Figure 13 illustrates the variation in emission components for different insulation thicknesses in the hottest (Zone I) and coldest (Zone IV) climate zones. In Zone I, initially, emissions from heating (\(M_{CO2,heat}\)) and cooling (\(M_{CO2,cool}\)) are substantial but decrease sharply as insulation thickness increases, indicating reduced energy consumption for heating and cooling. Emissions from heating (\(M_{CO2,heat}\)) are significantly higher in the coldest zone compared to the hottest zone, especially at lower insulation thicknesses. These emissions decrease substantially as insulation thickness increases, demonstrating the effectiveness of insulation in reducing heating demand. Emissions from cooling (\(M_{CO2,cool}\)) are relatively low in Zone IV due to the colder climate and show minimal change with increasing insulation thickness. The overall trend shows that when insulation thickness rises, substantial reductions in heating emissions can be realized in colder climates, making it an environmentally advantageous approach. Figure 13 shows the balance between initial emissions from insulation, plaster, and wall materials, and the savings in heating and cooling emissions with increased insulation thickness. In the hottest zone, the focus is on reducing cooling emissions, while in the coldest zone, reducing heating emissions is more significant. Figure 12: Cost components variation for different insulation thicknesses in the hottest and coldest climate.