Effects of closed vertical void on natural ventilation in double-loaded apartment building

We proposed a new design of an affordable apartment with a closed-vertical void to improve the indoor natural ventilation especially for the leeward side of the building and constructed a full-scale experimental house in Indonesia in 2020. This paper analyses the effects of the proposed ventilation system through field measurements in the experimental house. In the experimental house, the vertical-closed void with a width of 2.85 m was designed between the two rows of units. A pilotis was provided on the ground floor and a wind fin was attached to the bottom of the vertical void. The rooftop of the void was basically closed. First, vertical and horizontal distributions of wind velocities were measured at 125 points placed inside and outside the void with various window/door-opening conditions in 2022. Second, the volumetric flow rates (VFRs) for the void space as well as leeward units were measured through a tracer gas decay method and based on the measured inlet wind velocities respectively in 2023. The average wind velocity ratio, at the inlet of the pilotis was approximately 2.4 times higher than that in front of the building at the same height (reference point) due to the venturi effect. However, the increased winds did not reach the upper floor of the leeward units sufficiently even when the fin size was increased. Opening conditions of windows/doors significantly affected the wind velocity distribution in and around the void. Sufficient levels of VFR were obtained even in the upper floor of leeward units due to the increased static pressure inside the closed void. The proposed ventilation system would be able to provide sufficient cross ventilation to the double-loaded apartment buildings entirely with the increase in static pressure even for a mid-rise building.