Dynamic façades (DF) represent a promising approach to decarbonize the building sector, offering adaptability to environmental changes and users’ habits. This research focuses on the design, manufacturing, and performance analysis of a Dynamic Shading Device incorporating Phase Change Materials (DS-PCM), targeted to passively improve the indoor thermal environment. A performance-based design tool is under analysis to streamline and evaluate the performance of this dynamic shading device across different conditions. Therefore, this paper presents the research methodology, workflow, and preliminary results of a numerical simulation aimed at comprehensively characterizing the dynamic shading device with PCM and evaluating the influence of building location (i.e., climate zone) on thermal performance. The numerical model was developed and validated based on the experimental data obtained from real-scale prototype testing in two test rooms: one equipped with a conventional curtain as the reference case and the other featuring the dynamic shading device incorporating PCM. Dynamic building simulations demonstrated that the DS-PCM device reduced thermal discomfort by up to 8% compared to a traditional curtain, with its impact being most significant in Portugal’s moderate summer climate. These findings highlight the potential of this innovative dynamic shading system and emphasize the need for the development of a design tool for the sizing and optimizing of the dynamic shading system to aid designers and architects and offer a user-friendly interface for design purposes.