In the suburb of Tokyo - Yokohama metropolitan area, House in Yayoidai is located upon a hill demolished for residential district after the rapid growth of economy since 1970s.
Within a limited site area, and with restricted architectural laws like a set-back-regulation to keep houses less than 2 stories, in order to fulfil the space for living, people tend to have so called "underground." On the other, such an underground space tends to have much humidity and less light which are sometimes bad for human health or mentality.
Underground courtyard is efficient for resolving the problems. Whenever I am forced to plan the undergrounds, I always design the courtyard as a set of space related to interior.
In the house, I planed two courtyard; smaller one on north, larger one on south, which induces natural light an sunlight; as well as natural ventilation with a mechanism of gravity and air. The latter in particular, when the air in the south courtyard is heated, it gets lighter in weight, and it soars upward to the sky; in accordance with the movement, the air in the north side yard is forced to flow towards south side (less air pressure portion) when the basement interior is opened like a tunnel for air.
Text by Satoshi Okada