This project aims to propose a methodology for planning the analytical process involved in the resilient and energy-efficient retrofitting of cultural heritage buildings. Within this scope, the İzmir Radio and Democracy Museum, a historic residential building located within the borders of the historic port city of İzmir, in the Mediterranean climate zone, and currently adaptively reused as a museum, was selected as a case study. By examining existing literature, current approaches to the energy-efficient retrofitting of historic buildings were identified; those deemed suitable for the selected case study were then applied, and evaluated through thermal modeling, leading to the development of a model methodology for the energy-efficient retrofitting of other historic structures within the Mediterranean climate zone.