The feasibility of ventilation tower to enhance cross-ventilation performance in a detached house located in urban area

Cross-ventilation is effective not only for improving the indoor environment of urban housing but also as an energy-saving measure. Cross-ventilation using normal wall openings is difficult because the neighboring ridge space is small in major Japanese cities. To solve this problem, we propose installing a “Ventilation Tower” in a detached house and verify the effect of the tower. We conduct wind tunnel experiments to confirm the effectives of the Ventilation Tower as well as the reproductive accuracy of computational fluid dynamics (CFD) analyses. We calculated the ventilation rate and the average wind velocity in the occupied zone in gross building coverage ratios by CFD analyses. The data of CFD analysis correspond to experiment data. At 50% of gross building coverage ratio, the average ventilation rate of tower route is six times as much as that of the wall opening ventilation route. This is because the negative pressure at the tower section is hardly affected by the surrounding buildings. The ventilation rate of the wall opening route significantly decreased as the degree of neighboring building crowding increased. However, the ventilation rate of tower route is ensured regardless of the wind direction and building density.