The inlet aperture area should be around 20% of the floor area (or 30 m2) to achieve adequate natural ventilation for an acceptable comfort level. With such an aperture area, the air velocity in the first floor is around 0.4 m/s. The indoor air velocity distribution is rather uniform in the house we designed. When the aperture area is reduced to 13%, the corresponding indoor air velocity becomes 0.3 m/s. Therefore, it is desirable to use a ceiling fan to increase the air velocity if a large aperture area is not feasible. Another option would be the use of a solar chimney to enhance the natural ventilation by buoyancy effect.