自然通風對建築設計上扮演這相當重要的角色，利用建築物外部與內部之間的壓力差異使得空氣流通，可減少對機械通風的依賴，節約能源。而在都會地區許多建築緊密相鄰，因此空氣較不易流通，即使有門窗開口，仍有通風不良的狀況。本研究使用大渦流數值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。探討的參數包括建築物的大小、間距及排列方式。研究結果顯示：當兩棟建築物之間的距離大於兩倍主建築物高度時，主建築物的通風量就不受鄰近建築物的影響。而當下風處鄰近建築物的寬度及高度越大，上風處主要建築物通風量越小。研究發現鄰近建築物的寬度對主建築物通風的影響很大，當下風處鄰近建築物寬度為主建築物寬度兩倍時，主建築物背風面的風壓係數會大於迎風面的風壓係數，造成逆向通風之現象。此研究並發現主建築物位於鄰近建築物後方時，鄰近建築物的高度越高，遮蔽效應越明顯，主建築物通風量越小，且主建築物背風面的風壓係數皆高於迎風面的風壓係數，因此皆有逆向通風現象產生。

In densely-populated areas, where buildings are grouped closely together, wind-driven ventilation is strongly influenced by the surrounding buildings. 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 Large Eddy Simulation (LES) model to investigate the influences of adjacent building on wind-driven natural ventilation of a pitched-roof building. The influences of building height, width and spacing between the buildings were systemically studied. The results demonstrate that the influence of the adjacent building on the ventilation rate of the pitched roof building becomes insignificant when the spacing S  2.0He. The leeward pressure is larger than the windward pressure when the building width Wb/Wu = 2.0. In other words, the air flow will enter the building from the leeward opening and exit through the windward opening. Furthermore, when the pitched roof building is behind a tall flat-roof building, due to the sheltering effect, the ventilation rate of the pitched roof building is significantly reduced with the increasing height of the flat-roof building.

References
[1] Allard F. Natural ventilation in buildings: a design handbook, James and James Ltd., London, England; 1998.
[2] Aynsley R. Estimating summer wind driven natural ventilation potential for indoor thermal comfort. J Wind Eng Ind Aerodyn 1999; 83 (1-3):515-25.
[3] Linden PF. The fluid mechanics of natural ventilation. Annual Review of Fluid Mechanics 1999; 31:201-38.
[4] Kanda M, Maruta E. Characteristics of fluctuating wind pressure on long low-rise buildings with gable roofs. J Wind Eng Ind Aerodyn 1993; 50:173-182.
[5] Holmes J.D. Wind pressures on tropical housing. J Wind Eng Ind Aerodyn 1994; 53:105-123.
[6] Etheridge D. Natural ventilation of buildings: Theory and measurement and design. John Wiley and Sons, Chichester, England, 2012.
[7] Awbi HB. Ventilation of Buildings. 2nd ed. Taylor and Francis, London, England, 2003.
[8] Etheridge DW, Chiu YH. External flow effects on the discharge coefficients of two types of ventilation opening. J Wind Eng Ind Aerodyn 2007; 95:225-252.
[9] Etheridge D, Sandberg M. Building ventilation: Theory and Measurement. John Wiley and Sons, Chichester, England, 1996.
[10] Chu CR, Chiu YH, Chen YJ, Wang YW, Chou CP. Turbulence effects on the discharge coefficient and mean flow rate of wind-driven cross ventilation. Build Environ 2009; 44: 2064-72.
[11] Karava P, Stathopoulos T, Athienitis AK. Airflow assessment in cross-ventilated buildings with operable façade elements. Build Environ 2011; 46(1): 266-79.
[12] Johnson M-H, Zhai Z, Krarti M. Performance evaluation of network airflow models for natural ventilation. HVAC&R Research 2012; 18(3): 349-365.
[13] Chu CR, Chiu YH, Wang YW. An experimental study of wind-driven cross ventilation in partitioned buildings. Energy Build 2010; 42(5): 667-73. doi:10.1016/j.enbuild.2009.11.004.
[14] Chu CR, Wang YW. The loss factors of building openings for wind-driven ventilation. Build Environ 2010; 45(10): 2273-79. doi:10.1016/j.buildenv. 2010.04.010.
[15] Chu CR, Chiang BF. Wind-driven cross ventilation with internal obstacles. Energy Build 2013; 67,:01-09. doi:10.1016/j.enbuild.2013.07.086.
[16] Bauman FS, Ernest DR, Arens EA. The effects of surrounding buildings on wind pressure distribution and natural ventilation in long building rows, ASHRAE Transactions 1988; 94 (2): 1670-1695.
[17] Chang CH, Meroney RN. The effect of surroundings with different separation distances on surface pressures on low-rise buildings, Journal of Wind Engineering and Industrial Aerodynamics 2003; 91: 1039-1050.
[18] Tominaga Y, Akabayashi SI, Kitahara T, Arinami Y. Air flow around isolated gable-roof buildings with different roof pitches: Wind tunnel experiments and CFD simulations. Build Environ 2015; 84:204-213.
[19] Li JQ, Ward IC. Investigation of roof pitch and wind induced ventilation by computational fluid dynamics. 2006; PLEA2006 - The 23rd Conference on Passive and Low Energy Architecture.
[20] Evola G, Popov V. Computational analysis of wind driven natural ventilation in buildings. Energy Build 2006; 38:491-501.
[21] Kato S, Murakami S, Mochida A, Akabashi S, Tominaga Y. Velocity-pressure field of cross-ventilation with open windows analyzed by wind tunnel and numerical simulation. J Wind Eng Ind Aerodyn 1992; 41-44: 2575-86.
[22] Jiang Y, Chen Q. Effect of fluctuating wind direction on cross natural ventilation in buildings from large eddy simulation. Build Environ 2002; 37(4): 379-86.
[23] Ramponi R, Blocken B. CFD simulation of cross-ventilation flow for different isolated building configurations: validation with wind tunnel measurements and analysis of physical and numerical diffusion effects. J Wind Eng Ind Aerodyn 2012; 104-106: 408-18.
[24] Hu CH, Ohba M, Yoshie R. CFD modelling of unsteady cross ventilation flows using LES. J Wind Eng Ind Aerodyn 2008; 96(10-11):1692-706.
[25] Kobayashi T, Sagara K, Yamanaka T, Kotani H, Sandberg M. Power transportation inside stream tube of cross-ventilated simple shaped model and pitched roof house. Build Environ 2009; 44(7):1440-51.
[26] Ramponi R, Blocken B. CFD simulation of cross-ventilation for a generic isolated building: Impact of computational parameters. Build Environ 2012; 53:34-48.
[27] Germano M, Piomelli U, Moin P, Cabot WH. A dynamic subgrid scale eddy viscosity model. Physics of Fluids A 1991; 3(7): 1760-65.
[28] Smagorinsky J. General circulation experiments with the primitive equations. I. The basic experiment. Monthly Weather Review 1963; 91(3): 99-164.
[29] Chen Q. Ventilation performance prediction for buildings: A method overview and recent applications. Build Environ 2009;44:848-58. doi:10.1016/ j.buildenv.2008.05.025.
[30] Launder BE, Spalding DB. The numerical computation of turbulent flows. Computer Methods in Applied Mechanics and Engineering 1974; 3:269-89.
[31] Tominaga Y, Mochida A, Yoshie R, Kataoka H, Nozu T, Masaru Y, Shirasawa T. AIJ guidelines for practical applications of CFD to pedestrian wind environment around buildings. J Wind Eng Ind Aerodyn 2008; 96:1749-61.
[32] Blocken B, Stathopoulos T, Carmeliet J, CFD simulation of the atmospheric boundary layer: wall function problem, Atmospheric Environment 41 (2007) 238-252.