## 4 Conclusions  
In this study, analyses have been conducted for three different house usage scenarios: a house that is cooled but not heated (summer house), a house that is heated but not cooled (winter house), and a house that is both cooled and heated (all-season house). A summer house is typically located by the sea, in a resort area, and is occupied only during the summer. In contrast, a winter house is usually situated at the foothills of a mountain and is used only in the winter. An all-season house is located in the city center and is used throughout all four seasons. This study has clearly demonstrated that the periods of the year during which the building is used lead to significant differences in the ideal insulation thickness. For example, according to the results obtained for the north direction, the optimum insulation thicknesses are as follows: 5.02 cm when considering only heating energy requirements, 1.56 cm when considering only cooling energy requirements, and 6.08 cm when considering both cooling and heating (annual) energy requirements. It is observed that the aim of the building's use  
Figure 11: Variations of energy cost savings for various directions. Figure 12: Payback periods and energy saving rates for various directions. (summer house, winter house, or all-season house) is a significant factor in deciding the insulation thickness to be applied. In buildings both cooled and heated throughout the year, it is evident that the difference between the ideal insulation thicknesses determined for different directions reaches a maximum of 0.16 cm. It is found that the variation in the insulation thickness required for different wall orientations is limited and does not exceed 3%. For this reason, it has been concluded that for a building to be used throughout the year, different wall orientations do not greatly affect the ideal insulation thickness, and a single thickness could be preferred for all walls in insulation application. On the contrary, for a building that is only heated or only cooled, it has been observed that there is a difference of up to 0.53 cm between the ideal insulation thicknesses on the walls oriented in other directions. When examined in percentage terms, a significant difference of 35% is observed between the wall direction requiring the thickest insulation and the wall direction requiring the thinnest insulation. Hence, it would be fitting to utilize different insulation thicknesses for different directions in a seasonally used building, such as a summer or winter house. Consequently, it is found that the wall orientation has a greater impact on insulation thickness in buildings used only in summer or winter, and it is recommended that the appropriate insulation thickness be decided upon after conducting a directional analysis. When walls are insulated using optimum thicknesses obtained for each direction, there is a reduction in the total cost as expected. The most notable cost reduction is observed on the north-facing wall, showing a substantial decrease of 38.9%, whereas the south-facing wall exhibits the lowest cost decrease at 37.0%. The average decrease in the life cycle cost for all directions is calculated to be 38.0%. Under these analysis conditions, it is seen that such an investment would pay for itself in approximately six years, and the energy saving rate is found to be 70%. Moreover, a correlation is evident whereby walls with higher savings rates, notably those facing the north and northeast, correspond to shorter payback periods. Consequently, applying insulation in these directions is more advantageous. The most important thing that can be said about practical applications of thermal insulation according to wall directions is this: the south-facing walls of a building tend to receive more sunlight, leading to increased heating during the summer months. In such cases, applying additional insulation to these walls can help maintain cooler indoor temperatures.