Optimizing building envelope and window frame design for high-performance mixed-mode office buildings

In tropical climates, mixed-mode ventilation (MMV) is essential for optimizing thermal and energy performance in office buildings. This study investigates the impacts of wind-driven natural ventilation (NV) strategies and window frame design on the thermal and energy performance of MMV office buildings. A database of office buildings in São Paulo was used to develop a representative model to simulate various NV strategies and window frame configurations. artificial neural networks were employed to generate metamodels for annual cooling loads and cooling-degree hours, identifying optimal theoretical scenarios. Findings demonstrate that a holistic design integrating window-to-wall ratio (WWR), window frame design, and solar orientation is critical. In São Paulo's context, cross-ventilation on adjacent facades outperformed single-sided ventilation, reducing cooling loads by up to 25% and increasing air changes per hour (ACH) fourfold. The results emphasize treating WWR and orientation as integrated variables, notably, increasing WWR can serve as a deliberate cooling strategy if the resulting boost in NV potential offsets the higher thermal loads of larger glazed areas. This research underscores the significance of optimized envelope and window design in achieving energy-efficient MMV office buildings