Impact of planar area ratio and opening positions on natural cross ventilation performance in sheltered high-rise buildings: A simulation study

Abstract

This paper studies the impact of planar area ratio (λP) and opening positions on natural cross ventilation performance of a sheltered three-level high-rise building through numerical simulations. Three building clusters of different λP and five different opening configurations each were assessed. To improve the accuracy of the numerical simulations, a novel calibration method utilizing 2k full-factorial design of experiment (DoE) approach was proposed to determine the closure coefficients of the Standard k−ε (SKE) turbulence model. Various parameters such as velocity profile (U/UH), pressure difference (ΔCp), turbulence kinetic energy (TKE), dimensionless flow rate (DFR), age of air (AOA) and air exchange efficiency (AEE) were examined. On level 1, distinct variations in DFR, AEE and AOA were observed for different λP values. Maximum DFR and AEE and maximum AOA are achieved when λP=0.25 for all opening configurations. Conversely, the impact of λP is minor for levels 2 and 3. Specific opening configurations, such as top-bottom and top-top on levels 1 and 2, and center-center and bottom-top on level 3, demonstrate favorable AEE of about 45–50%. The trade-off between AEE and DFR suggests that the bottom-bottom configuration performs best on level 1, while top-top and top-bottom configurations work best on level 2, and the center-center configuration is the best on level 3. The presence or absence of openings on levels 1 and 3 do not significantly affect the indoor airflow on level 2. The insights and recommendations derived from this study have practical implications for sustainable high-rise building design.