In hot and humid climates such as the city of Abadan, a significant portion of building energy consumption is allocated to cooling systems. One of the main contributing factors to this high energy demand is thermal loss through the exterior building envelopes. This study aims to evaluate and compare the amount of energy loss in external walls constructed with conventional materials (such as brick and cement block) and those incorporating thermal insulation materials, including Expanded Polystyrene (EPS), Extruded Polystyrene (XPS), rock wool, glass wool, and Autoclaved Aerated Concrete (AAC or Hebel blocks), under the climatic conditions of Abadan. The research methodology is based on a prescriptive approach to analyzing the thermal behavior of building envelopes using the balance-based prescriptive design software developed by the Iranian Ministry of Roads and Urban Development, according to the 2019 (1399) edition of the National Building Code, Part 19. The climate conditions were defined using meteorological data from the Abadan Meteorological Organization. The results indicate that while the use of the aforementioned thermal insulation materials in the outer layer of walls does not entirely prevent heat transfer, it significantly reduces it and substantially improves the building’s thermal performance. Among the evaluated insulation materials, comparative analysis revealed that glass wool exhibited the best performance in terms of thermal behavior