## 3 Results
Figure 7: Interval plot of (**a**) optimum insulation thickness values (m) and (**b**) annual financial gains (USD/m\({}^{2}\)) with EPS insulation material for Adyaman. Considering all the calculations made, the optimum insulation thickness varies between 0.0169 and 0.0546 m when the fuel type is natural gas, while it takes values between 0.0173 and 0.0725 m in electricity use and 0.00-0.0234 m in coal use. The highest gain is obtained as 20.05 USD/m\({}^{2}\) per year when EPS is used as insulation material in a 15 cm thick concrete wall, similar to that in Hatay province. The situation where it is not financially economical to make insulation is the application of EPS, XPS, or rock wool as the insulation material to the 15 cm thick Ytong wall structure in coal use. The highest insulation cost is calculated as 20.056 USD/m\({}^{2}\) when EPS is employed as the insulation material on a 15 cm concrete wall with an electric fuel type. This value was 4.38 USD/m\({}^{2}\) when the fuel type was coal and 19.69 USD/m\({}^{2}\) when the fuel type was natural gas. Although the fuel type changes, the highest insulation cost is for this wall type and insulation material. Considering the payback periods, the shortest periods are obtained in the case where EPS insulation material is used in the 15 cm thick concrete wall where the highest gain is obtained. However, this period is 0.56 years in natural gas and electricity use. The city of Malatya, which was affected by the earthquake, is located in the third degree-day zone. In the case of using XPS as insulation material, the insulation thickness and financial gain for different wall types are given in Figure 9, and optimum insulation thickness values and annual financial gains with different insulation materials are given in Table 5.  
In the five wall types examined in Figure 9, the highest insulation thickness was obtained when electricity was used as the fuel, while the smallest insulation thickness was achieved with coal. This order remained consistent regardless of the wall type. For a 15 cm concrete wall, the optimum insulation thickness was 0.0490 m when electricity was used, whereas it decreased to 0.0204 m when coal was considered as fuel. The lowest optimum insulation thicknesses were observed in the Ytong wall type. Additionally, the annual financial gain was higher when electricity was used as the fuel compared to other fuel types. In case EPS is used as the insulation material and electricity, natural gas and coal are used as the fuel, optimum insulation thicknesses and annual financial gains for five different walls are given in Figure 10.  
Figure 9: Interval plot of (**a**) optimum insulation thickness values (m) and (**b**) annual financial gains (USD/m\({}^{2}\)) with XPS insulation material for Malatya. According to Figure 10, the smallest insulation thickness was obtained when coal was used as the fuel. The biggest value of the optimum insulation thickness was obtained when electricity was used as the fuel in other wall types. In case rock wool is used as the insulation material and electricity, natural gas and coal are used as the fuel, optimum insulation thicknesses and annual financial gains for five different walls are given in Figure 11.  
According to Figure 11, the smallest insulation thickness was obtained when coal gas was used as the fuel. This value was 0.0182 m for a 15 cm concrete wall, while it decreased to 0.000 m for the Ytong wall type. The biggest value of the optimum insulation thickness was obtained when electricity was used as the fuel in other wall types. When considering the 22 cm solid brick wall for Malatya in Figure 10, the optimum insulation thicknesses are calculated as 0.0887 m, 0.0604 m, and 0.0235 m for electricity, natural gas, and coal usage, respectively. For Adyaman province, these values are 0.0725 m, 0.0485 m, and 0.0174 m, as shown in Figure 7a. In Hatay, the corresponding values are 0.0419 m, 0.0262 m, and 0.0058 m, as depicted in Figure 3a.