Utilization of Cross-ventilation in High-density Urban Areas

The increased density of buildings in urban areas in Japan over the past several years has meant that less outdoor wind blows into buildings. Additionally, houses with many or large-size of openings are difficult to build due to concerns about security and privacy. In the present study, we have investigated the cross-ventilation characteristics of void, monitor roof and wind tower for the purpose of improving the cross-ventilation in detached houses built in high-density urban areas based on wind tunnel experiment and flow-network model calculation. At first, wind-pressure characteristics of a detached house in high-density urban areas were obtained by the wind tunnel experiment. From this result, we found that It is difficult to ensure adequate cross-ventilation in houses located in high-density urban areas by only openings in the wall surface. So, void, monitor roof and wind tower have been investigated as techniques of improving the cross-ventilation. Wind-pressure characteristics of each technique were examined by wind tunnel experiment. And rates of cross-ventilation flow from cases (i.e., void, monitor roof and normal roof) were calculated by flow-network model using wind-pressure coefficients from previous experiments. It can be concluded that void is a very effective technique for improving cross-ventilation in detached houses.