## 2 Literature Review
Key design aspects--such as shading elements and glazing optical properties--play a critical role in governing heat transfer and ventilation effectiveness. Additionally, the interaction between cavity depth and airflow rate significantly influences overall system performance. In another study [24], a two-dimensional numerical model of an innovative passive facade configuration was developed. This model incorporates an optical thin-film material composed of tungsten-doped vanadium dioxide (VO\({}_{2}\)) and an aluminum nitride (AlN) layer, selected for its high thermal absorption capacity. A parametric study on air cavity thickness revealed a notable decrease in thermal loads during both winter and summer periods. The analysis also indicated a marked enhancement in indoor thermal comfort, with seasonal fluctuations in interior surface temperatures. A detailed investigation into the combined effects of natural convection and radiation within the cavity highlighted their substantial impact on system efficiency. In this study [25], the passive facade concept is advanced by incorporating an adaptive external layer featuring a rectilinear kirigami-inspired cut. This section can be selectively actuated to open the facade for ventilation while simultaneously reorienting the outer surface to follow the sun's trajectory. The research aims to evaluate the potential advantages of integrating this approach into building facades. Findings demonstrated improved solar energy absorption, increased ventilation efficiency, and better indoor temperature regulation. The research presented in [26] integrates a building energy simulation tool with a computational fluid dynamics (CFD) package to examine the thermal performance of a passive facade equipped with a solar-exposed shading device. The findings reveal that air temperature within the facade cavity increases almost linearly towards the upper section, with elevated temperatures near the shading element. Another investigation [27] involves a comparative analysis between experimental data and numerical simulations conducted in ANSYS Fluent 17, focusing on a passive facade. Optimization strategies are proposed based on temperature and airflow distribution. The study identified the presence of natural free convection and recirculation zones in the experimental model and validated the chimney effect through temperature profiles obtained from both experimental and simulated data. Additionally, a two-dimensional numerical analysis of a passive facade considering both mechanical and natural ventilation was conducted using the finite volume method [28]. The study highlights the complexity in accurately determining the heat transfer coefficient and notes that numerical outcomes are highly dependent on input parameter accuracy, the value of the convective heat transfer coefficient, and numerical approximation errors. A separate two-dimensional numerical investigation [29] explored natural convection heat transfer within a tall cavity, examining both laminar and turbulent regimes using the k-\(\epsilon\) turbulence model. The study found that for turbulent convection, the Nusselt number rises with increasing aspect ratio, whereas in laminar flow, it declines as the aspect ratio becomes larger. In another study [30], researchers applied the zonal energy equation to simulate heat flux and temperature distribution across a passive facade. The findings confirmed that the zonal method is a practical tool for assessing facade performance, offering quick results with minimal computational effort. Concerning airflow velocity measurements in ventilated passive facades, one study [31] evaluated three conventional techniques. These included pressure-based methods at facade openings, anemometric measurements, and airflow visualization using tracer gas injection. Several case studies have explored the benefits of passive facades in improving building energy efficiency. A selection of such studies is summarized below.