水平導風板對室內自然通風之效益研究

A Study on the Efficacy of Horizontal Wind Deflector on Indoor Natural Ventilation

本研究以居室空間單側通風模式為探討對象，探究水平導風板應用於建築外殼開口部對室內自然通風之效益，研究方法乃運用計算流體力學（CFD ）數值解析方式進行室內穩態氣流場、溫度場模擬，配合足尺實驗方法檢證模擬之精確性，作為數值模擬邊界條件設定之依據，設定不同的外部環境風速，計算並分析不同水平導風板深度對室內換氣率（ACH ）、二氧化碳濃度、溫度垂直分佈及風擊不滿意度（DR ）之影響，基於上述綜合評估以建議最佳的構造尺寸。研究結果顯示：9cm 以上水平導風板有助於提升單側通風時之換氣率，並隨導風板深度而遞增，尤其當外部風速小（0.3m/s ）的時候較為明顯，但風擊也隨之提高，當外部風速為2m/s 以下、導風板深度需為36cm 以下，才能完全符合ASHRAE 之DR 標準；而導風板深度為4cm 時，不僅無法提升室內換氣，在高風速下（1~2m/s ），還會減少5~13% 的換氣率；若綜合考量各評估項目，導風板深度以18~48cm 為較佳的選擇。

This study focused on the single side ventilation model of the residential room, and discussed the efficacy of the horizontal wind deflector of the exterior opening of the building on the indoor natural ventilation. The research method used the numerical algorithm of computational fluid dynamics (CFD) to simulate the steady-state air field and temperature field indoor, and used full-scale experiment to verify the accuracy of the simulation as the reference for boundary condition setting of the numerical simulation. Different external wind speeds were set to compute the effects of different depths of horizontal wind deflector on the indoor air change rate (ACH), vertical distribution of temperature, concentration of carbon dioxide, and predicted percentage of people dissatisfied due to draft (DR). Based on the composite evaluation, the best structural sized was suggested. The results showed that horizontal wind deflector over 9cm can help to improve the ACH of single-sided ventilation, and the effect would decrease as the depth of deflector increases. It was most obvious when the external wind speed was small (0.3m/s), yet the wind impact would increase. When the external wind speed was under 2m/s, the depth of horizontal wind deflector needed to be under 36 cm to meet the DR standard of ASHRAE. When the depth was 4cm, it not only was unable to improve the ACH, but also would reduce 5~13% ACH under high wind speed (1~2m/s). For consideration of each evaluating factor, the depth of the horizontal wind deflector is suggested to be 18~48 cm.