Increased energy efficiency is critically important for both achieving environmental sustainability and realizing economic savings. Specifically, insulation materials used in buildings play a key role by minimizing heat losses, which in turn reduces energy consumption. Furthermore, reduced energy usage leads to lower carbon emissions, mitigating adverse environmental impacts. This study focuses on improving building energy performance in Türkiye's Southeastern Anatolia Region through a comprehensive energy analysis. Two distinct insulation materials (artificial polyurethane and natural glass wool) and two fuel types (fuel oil and LPG) were investigated. The degree-day method was employed to calculate the optimal insulation thicknesses for eight provinces within the region. Subsequently, the annual net savings and payback periods resulting from these optimized insulation applications were determined. The study culminates in a comparison of the annual energy requirements of insulated versus uninsulated buildings, providing a detailed examination of the potential for energy savings. This research aims to contribute to informed decision-making regarding building energy performance enhancements and offers valuable insights to shape future sustainable energy policies.