Thermal performance analysis of energy-active window systems with integrated airflow elements

Optimizing building envelope systems is essential for improving thermal comfort and energy efficiency. Glazed sections are typically the weakest in terms of heat transfer, requiring targeted enhancement. This study examines the thermal performance of Energy-Active Window (EAW) systems equipped with internal airflow-modifying elements to enhance convective heat transfer and mitigate heat accumulation within the window cavity. Computational Fluid Dynamics (CFD) simulations were performed under steady-state conditions to analyze temperature distribution and convective behavior. Lower airflow velocities (0.24 m/s) improved thermal uptake, resulting in an outflow temperature of 38.8 °C and an average pane temperature difference (ΔT) of 15.9 °C. In contrast, higher velocities (0.57 m/s) reduced these values to 35.36 °C and 15.73 °C, respectively. To further improve performance, circular, square, and triangular bar-shaped elements were investigated. The square bar configuration (SA2), with 3 bars spaced 0.1 m apart, achieved the highest efficiency, yielding an outflow temperature of 39.04 °C and a ΔT of 16.06 °C. Reducing the spacing to 0.05 m increased ΔT to 16.45 °C. The inner glazing temperature of 23.3 °C confirmed enhanced heat removal due to increased airflow disruption. These findings underscore the significance of the geometry and placement of internal elements in improving the thermal performance of EAW systems, with configuration SA₂ emerging as the most thermally effective design.