Optimizing window design for natural ventilation in high-rise social housing toward livable space

The livability of compact high-rise social housing in tropical climates depends heavily on thermal comfort, particularly in units relying solely on natural ventilation. This study investigates how window design— specifically Openable Window Ratio (OWR) and Window Height Shading (WHS)—affects thermal comfort in naturally ventilated units of a public rental apartment in Jakarta. Using validated CFD simulations calibrated with real climate data at peak discomfort hours (13:00), thirty-six window variants were tested across three building levels (floors 4, 10, and 16). Thermal comfort was evaluated using the ASHRAE 55 standard with PMV, PPD, and thermal sensation metrics. Results show that a window design with 90% OWR and 100% WHS consistently improves thermal comfort across all heights, reducing PPD from over 80% to under 30%. Notably, even with single-sided ventilation—a common limitation in such housing—specific window configurations successfully shifted indoor conditions toward acceptable comfort thresholds. These findings provide actionable design guidelines for enhancing livable space in tropical high-rise social housing.