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Architects: TAISEI DESIGN Planners Architects & Engineers
- Year: 2022
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Photographs:Naoki Kumagai Photo Office, Inc., Taisei Corporation
Text description provided by the architects. This project involved preserving and restoring a modernist building built in 1967 in Ginza, Tokyo, known as an example of Metabolism architecture. This building is a distinctive work by Kenzo Tange, one of Japan's most celebrated architects, who devised a creative new form for a small site located in a place that symbolizes Japan's post-war period of rapid economic growth. The cylindrical core at the center of the building houses vertical circulation routes such as stairs, elevators, and piping. The office spaces protrude outwards from the core, giving it a distinctive appearance.
The paintwork of the exterior walls was renovated in 1993, and the interior facilities and the exterior were renovated in 1999. This time, structural and functional reinforcement and an overall renovation were carried out to extend the building's lifespan for another several decades.
In particular, given the unique structural system, seismic retrofitting was planned to maximize the reinforcement effect while minimizing the space required by identifying the building's weak points through seismic response analysis. Carbon fiber sheets were attached to the cylindrical core wall legs (around the first floor) from the inside as bending reinforcement and thin steel plates were installed as shear reinforcement for the lower floors (first to fifth floors.) This allowed for a significant increase in earthquake resistance while maintaining the building's original form and also ensuring the usability of the small spaces.
As for the exterior, we conducted paint inspections on the walls inside and outside the cylinder to reproduce the original colors at the time of construction. We checked the paint history of the inspection points and compared the colors with photographs from the construction period to identify the colors.
In addition, the underside of the eaves and the cylindrical shape were lit up, and LED lighting was introduced in the interior. This transformed the building's appearance at night and emphasized its presence as a local landmark, day and night.
For the interior and facilities, we focused on reflecting the needs of today's users. Specifically, we enhanced security, implemented business continuity planning (BCP) measures, ensured barrier-free access, and added new shared spaces and pilots. As a result, more comfortable and user-friendly working environments have been achieved.
The project's most significant focus was identifying the areas that needed renovation and those that needed preservation and recording each area's history before restoring it. This metabolism architecture will be passed on to the next generation while adding new functions and value.
