Combining perforated ceiling and attic ventilation for night cooling in a single-zone building: CFD analysis

The ventilative cooling potential of a perforated ceiling in combination with attic ventilation during the night in naturally ventilated residential buildings in tropical climate is investigated. 3D steady Reynolds-averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) simulations were carried out with the RNG k-ε turbulence model under non-isothermal conditions for two different single zone realistic building models, C1 (building without perforated ceiling and attic ventilation) and C2 (with perforated ceiling (40% porosity) and attic ventilation). The simulations were conducted for nighttime conditions in Indonesia (Makassar), as obtained from measured weather data, to represent real-life conditions as much as possible. The CFD simulations were performed for the wind direction perpendicular to the building facade with the window openings. The heat removal effectiveness (HRE) and air changes per hour (ACH) were assessed for both building configurations. The results show that building C2 facilitates a faster removal of heat from the occupied zone compared to building C1. This leads to a reduction of indoor air temperature that is lower by 0.8 °C for case C2 compared to case C1. Moreover, C2 displays higher values for both HRE (1.25 vs. 1.00) and ACH (34.1 h-1 vs. 27.9 h-1).