## 6 Conclusions  
The conclusions drawn from the detailed analysis of temperature distribution and velocity profiles within the cavity of the passive facade highlight a complex interdependence between the geometry of the air channel and the system's energy efficiency. Specifically, cavity width emerges as a critical design parameter, exerting a direct influence on both the internal thermal and hydrodynamic regimes, and consequently affecting the facade'soverall performance in terms of energy conservation. A clear correlation is observed between the width of the passive facade cavity, the air mass flow rate, and the transferred heat flux. As the channel width increases, there is a corresponding increase in both the mass flow rate of air circulating through the cavity and the amount of heat transferred. The comparative analysis of the temperature fields in the XY plane demonstrated that a greater cavity width (12 cm) results in higher maximum temperatures at the outer edge of the facade, suggesting enhanced thermal transfer to the interior and reduced heat loss to the exterior. This observation, combined with the higher total thermal variation observed in wider cavity configurations, indicates an increased sensitivity of the thermal regime to air channel dimensions. From a fluid dynamics perspective, the parabolic velocity profiles--characteristic of a laminar flow regime--indicate a direct dependence of velocity magnitude on cavity width. Wider channels allow for higher maximum velocities, which imply an increased volumetric airflow through the facade. Greater airflow, driven by natural convection, contributes to more uniform temperature distribution within the cavity and more efficient heat removal in the warm season or preheating of incoming air during the cold season--both essential for optimizing the building's energy performance. These characteristics not only reduce the energy demand for heating or cooling but also enhance indoor comfort and building sustainability. Although the \"stack effect\" is a well-known concept, its detailed demonstration and explanation, through parabolic velocity profiles and direct correlation with increased heat flux within the specific context of passive facades with varying widths, adds further confirmation and a deeper understanding of its vital role in the energy performance of these systems. Even though studies on ventilated cavities exist, such an explicit and quantified comparative analysis of the direct influence of only cavity width across multiple profiles (temperature, velocity, heat flux, mass flow rate) for five distinct configurations contributes to a superior understanding of the processes and phenomena occurring within the cavity of a passive facade. This allows for the precise identification of the most efficient configuration within the specific context investigated. The work not only analyzes but also translates its results into practical recommendations, directly emphasizing that passive facades with optimized cavities (in this case, 12 cm) are an efficient and recommendable solution for achieving nZEB standards. This direct link between research and practical applications for modern buildings adds significant value. The present study focused on the influence of cavity width; however, the energy performance of a passive facade can vary significantly depending on the specific climatic context and other construction parameters of the building. A detailed quantification of specific energy benefits under various scenarios was not undertaken. The study primarily relies on numerical simulations. The authors emphasize the necessity of validating these simulations through experimental studies that evaluate the performance of passive facades under real and diverse climatic conditions by monitoring relevant physical parameters. Moreover, this study does not include an in-depth analysis of material and manufacturing costs, long-term durability, or the environmental impact associated with different passive facade configurations.