Cross Ventilation Enhancement in Small Dwelling Units with Double-loaded Corridor: A CFD and Field Study in Bangkok

Abstract

Small dwelling units in urban multi-storey buildings often suffer from inadequate ventilation due to single-sided openings, which negatively impacts thermal comfort and indoor air quality. This study investigated solutions to enhance cross ventilation, adopting a typical studio-unit layout of a Bangkok apartment as a case study. CFD simulations were conducted for 48 scenarios, varying by the internal opening design, wind direction, and unit location. Each scenario was evaluated using the average indoor velocity coefficient at occupied level (C_vi) and the product of the velocity coefficient at openings and inlet area (C_vo × A). It was found that the base case unit (BC) provided the poorest performance (mean C_vi = 0.01; C_vo × A = 0.02). The improved unit with a transom window (C1) exhibited higher mean C_vi and C_vo × A values (0.09 and 0.26, respectively), while the unit improved with a louvre door (C2) achieved the highest values (0.20 and 0.76, respectively). The most significant parameter for improving mean C_vi and C_vo × A was found to be the opening design, followed by wind direction in relation to building orientation, and unit location, respectively. Further analysis based on Bangkok’s climate indicated that the ventilation rate of most BC unit scenarios failed to meet the recommended criterion (5.0 ACH). In comparison, the C1 unit and C2 unit achieved ACH ranging from 12.6 to 173.7, consistently meeting the recommended criterion throughout the year across all building orientations and unit locations. Moreover, several scenarios of the C2 unit can provide occupied-level air velocities that pass the recommended criterion for thermal comfort throughout the year. The findings revealed both the potential and limitations of using internal openings for cross ventilation in compact units to improve indoor air quality and thermal comfort, providing practical solutions for architects and policymakers to enhance sustainable residential design.