都會地區的建築物大多緊密相連，阻礙空氣流動，造成室外風場微弱，空氣不易流通。因此即使建築物前後皆有向外的窗戶開口，仍會導致建築物通風不良的狀況，室內容易產生悶熱、不舒適的居室環境。本研究採用計算流體動力學模式研究受周遭其他建築物影響的建築物表面風壓及通風量換氣率。探討參數建築物的深度、高度、寬度及間距。結果顯示當主建築物受到上風處建築物的阻擋，不僅會影響建築物表面壓力係數，也會導致通風量的減少，特別是在兩棟建築物的距離為一半建築物高度對下風處主建築物影響最為明顯。而當兩棟建築物的距離大於五倍建築物高度時，上風處建築物就不會影響下風處主建築物；且兩棟建築物的距離固定為一倍建築物高度時，改變上風處建築物的高度Hu或寬度Wu，當Hu大於1.5Hb或Wu大於1.5Wb時，主建築物背風面壓力係數會高於迎風面的壓力係數，會產生逆向通風的現象，其通風量會折減一半以上。研究結果亦發現單棟建築物的風壓通風量不受建築物寬度的影響，但建築物的深度變大時，因為建築物迎風、背風面壓差改變導致通風量變小，當建築物深度大於3.5倍建築物室內高度時，通風量就不再受深度影響。In densely-populated areas, where buildings are grouped closely together, wind-driven ventilation is strongly influenced by the surrounding structures. The sheltering effect of the surrounding built-up environment can reduce the wind speed and wind-driven ventilation rate. This study used a three-dimensional Computational Fluid Dynamics (CFD) model to investigate the influences of adjacent building on wind-driven natural ventilation of the downwind building. The influences of building depth, height, width and spacing between the buildings were systemically studied. The simulation results demonstrated that the ventilation rate decreases as the building depth increases, and the influence of building width on the cross ventilation rate of a single building is insignificant. When two identical buildings placed in tandem arrangement, the ventilation rate of downwind building, compared to that of a single building, was notably reduced by 50% when the spacing between two buildings is less than three times of building height. The numerical results also demonstrate that the ventilation rate of downwind building will be significantly reduced when the upwind building width and height was Wu/Wb≧1.5or Hu/Hb≧1.5.
