Wind-driven natural ventilation of cubic buildings in rural and suburban areas

Abstract

Model experiments were performed in a boundary layer wind tunnel to study wind-driven natural ventilation of a cubic building. The focus is on the effect of the atmospheric boundary layer (ABL) characteristics, i.e., rural and suburban ABL wind conditions, on the wind-driven natural building ventilation, an issue previously not adequately studied. This was investigated for a single building standing alone (isolated) and a building surrounded by other buildings (sheltered), where the effects of the spacing between buildings, flow velocities, and incidence angles in the single-sided and cross-ventilation arrangements were analyzed. The parameter used to quantify the natural building ventilation was the air change rate (ACH). The results indicate several important findings. The ABL characteristics strongly influence the intensity of ventilation for both the stand-alone building and the one embedded in the neighborhood. For the single-sided ventilation, the maximal relative difference between the rural and suburban ACH of the stand-alone building is 15%, while that difference may reach 20% for the building situated in a neighborhood. Cross ventilation of a building surrounded by other closely packed buildings is characterized by greater ACH rates in rural ABL conditions; the maximum ACH is in the case of the flow perpendicular to the window plane. For higher spacing between buildings, the maximum ACH is at the flow incidence angles between 30° and 60°. Ventilation rates of buildings subjected to the rural ABL are generally more sensitive to changes in the flow direction.