This simple yet elegant home by Key Architects is not just an intriguing example of modern Japanese design — it’s also is the first certified Passive House in Japan. Simplicity has its rewards, and when the Passive House standard is synthesized with Japan’s refined building sensibility the result is a powerful combination that can move green building to a new level. This ultra-efficient house is a far cry from traditional Japanese housing, which used thin wall construction and single-pane windows, which even today is still quit typical.
Key Architects‘ Passive House uses very detailed construction materials and building techniques to improve the shell’s r-value to the point where much of the interior heating is provided by the appliances and occupants of the building. This home is a great example of the Passive House standard‘s building techniques — it features triple-pane windows, thick walls for insulation, and a minimum of exterior joints, which are prone to air leaks and thermal bridging. The core of the HVAC system is a HRV — or Heat Recovery Unit — that provides a constant supply of fresh, filtered air. A building becomes Passive House certified when, amongst other things it achieves a strict kWh per square-foot per year energy profile — in this case the home’s rating is ¼ of what is considered average.
The Passive House standard is becoming an important measure of sustainable building, and in Japan’s climate these homes would save an enormous amount of energy. This home is located about 50 miles southwest of Tokyo in the resort town of Kamakura city. Its design helps diminish the criticism that the ‘boxyness’ of many passive houses is not beautiful — and we also really like the roof deck.