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Kotaro IDE and Casa Guscio

Karuizawa, Distretto di Kitasaku, Prefettura di Nagano, Giappone• ★★★★☆• 347 views
Renee Carlington
Karuizawa
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About Kotaro IDE and Casa Guscio

Kotaro IDE and Casa Guscio - Karuizawa | Secret World Trip Planner

The shell house, designed by Japanese architect Kotaro IDE, is a very special house.

Built in the forest, in Nagano, Japan, it was designed as a holiday home, able to withstand the temperatures of wet summers and cold winters typical of the region. To avoid this, the architect IDE chose not to use a wooden structure, a typical material used for the construction of villas in the area, because of its sensitivity to climate change. Instead, he preferred to use reinforced concrete to give stability to the climatic conditions, even though it is a material that at first glance does not integrate well into an ecological house project. The J-structure takes shape from the combination of two oval cylindrical masses of different sizes, cut by the curves. The straight part of the J, the smaller mass, connects to the curved section of the J, the more voluminous part. The wall of the highest part of the oval building is 35 cm thick; its width gradually increases to 75 cm on both sides to meet structural parameters. The curved lines are visible on the edge and the three-dimensional curved surface makes a twist and is partly shown on the cut surfaces. The floor is raised 140 cm above the ground, with the lower half of the shell projecting outwards, supporting the terrace at the same height. All outlets for the air ducts and exhaust pipes were installed in the strip below, so that air could flow outside through the ventilation duct of the terrace. Semi-openable windows help to maximise natural ventilation (we have no air conditioning systems in the central parts). While at first glance the space of the oval cylinder may seem badly exploited, in reality its functionality is optimized to the maximum with the furniture all located in its lower half".

The central control system - perfectly integrated in the architectural design - allows to monitor with three buttons all mechanical and electronic devices. The installation of an underfloor heating system, custom-designed for Shell House, allows a significant reduction in energy consumption.

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Frequently Asked Questions

IDE chose reinforced concrete to provide structural stability against Nagano's extreme climate conditions, including wet summers and cold winters that would damage traditional wooden structures typical in the region. Although concrete may seem counterintuitive for an ecological house, it was the practical solution to ensure the holiday home could withstand the region's temperature fluctuations.
The J-structure combines two oval cylindrical masses of different sizes connected by curves, with the smaller mass forming the straight part of the J and the larger, more voluminous section forming the curved part. The three-dimensional curved surfaces create a distinctive architectural twist that's visible on the building's edges and cut surfaces.
The house uses natural ventilation through semi-openable windows and a ventilation duct system integrated into the terrace, with all air outlets and exhaust pipes cleverly installed in the strip below the raised floor. This passive cooling design eliminates the need for air conditioning systems in the central living areas.
The floor is raised 140 cm above ground, with the lower half of the shell structure projecting outward to support a terrace at the same height. This elevated design creates space for mechanical systems and air circulation beneath while maximizing usable living space above.
Although the oval cylinder spaces might initially appear inefficiently designed, all furniture is strategically positioned in the lower half to optimize functionality and maximize usable space. The central control system allows guests to manage all mechanical and electronic devices from three convenient buttons integrated throughout the home.