More than a city office: a new site to see
▼项目与周边环境鸟瞰，aerial view of the project and surrounding environment © ToLoLo studio
Known for its beautiful archipelago of some 700 islands, Japan’s Setonaikai (Seto Inland Sea), is the largest waterway of its type in the country. Located in the center of the sea, Onomichi is surrounded by the Onomichi Channel, a key historic point for maritime traffic, and by a trio of mountains home to ancient temples. Used as a setting for many literary works and movies, the area’s scenery has more recently been recognized as a Japan Heritage Site. It has also become a mecca for cyclists, and attracts both domestic and overseas interest.
▼海上政府大楼，A Veritable Ship at Sea © ToLoLo studio
Onomichi City Office is more than a government office building. The first and second floors and the rooftop have terraces with a view of the garden-like landscape. Connected by stairwell, they remain open to the public after office hours and on holidays. More than a municipal administrative facility, the goal was to create a government building that would also serve as a new Onomichi landmark, and a site to see.
▼临海一侧立面，overview of the facade along the seaside © SATOH PHOTO
▼立面细部，detail of the facade © SATOH PHOTO
▼景观露台，terraces with a view of the garden-like landscape © SATOH PHOTO
An urban-friendly, sea-embracing design
In making the most of its location facing the Onomichi waterway, the goal was to create not a government building with a view of the sea, but a government building on the sea. Protruding seaward to the south, the contours erase all but the sea from view, creating the sensation of floating on water.
▼入口立面夜景，night view of the entrance facade © SATOH PHOTO
▼入口雨棚，Entrance canopy © SATOH PHOTO
Outdoor staircase leading to the second floor viewing terrace © SATOH PHOTO
In addition, the southward slope of the building blocks direct light and reduces the heat load. On the other hand, its gradual setback from the north side urban area lined with detached houses is unoppressive, allowing unobstructed sunlight. Truss columns that match the building’s incline are employed around the perimeter to increase horizontal stiffness and maximize the seismic isolation effect. The truss shape also minimizes the pile count by consolidating foundation beam columns, thereby reducing construction cost and environmental impact.
▼由室外露台看海上美景，Views over the sea from the outdoor terrace © SATOH PHOTO
A laid-back architecture that appeals to the senses
The objective with this design was to create an architecture that embodied unique “Onomichi time” – where ferryboats come and go and the daily pace is leisurely. A building with a human touch would be more appealing to the five senses than a “functionally supreme” homogenous structure, it was thought.
▼入口，Entrance © ToLoLo studio
▼中庭，Atrium © ToLoLo studio
Atrium staircase runs through the building © SATOH PHOTO
▼办公环境概览，overview of the office © ToLoLo studio
▼会客室，Meeting room ©SATOH PHOTO
Windows can be opened and closed freely by office workers. The false ceiling was eliminated in the office space and ceiling fans installed to generate airflow with consistent temperature and humidity. The lighting is simple, with fixtures attached to cable racks which can be freely wired without the installation of raised floors. Wooden louvers, polished concrete floors, and bare steel eaves were selected to allow for some unevenness and color variation. The laid-back, customizable architecture should gain in character and appreciation as time passes.
▼会场，Conference ©SATOH PHOTO
▼会场天花板细部，detail of the conference room’s ceiling © SATOH PHOTO
Turning the everyday into the exceptional (“wow!”)
▼海上运输与滚压成型技术，Transporting materials by sea and use roll forming © Nikken Sekkei
Onomichi boasts the largest shipbuilding and maritime transport industries in Japan. Thus, incorporating relevant technologies into the architectural design seemed like a superb idea. The building’s exterior is comprised of 12mm thick steel plates formed at a shipmaker and delivered directly by sea. The soft outer look was accomplished by employing the unique shipbuilder’s “gyotetsu” (roll forming) technique, in which three-dimensional shapes are processed by repeated heating and cooling.
▼滚压成型加工现场，Rolling molding processing site ©Nikken Sekkei
Transporting materials by sea meant that size limits no longer applied, so that conventional architectural scales could be re-imagined: hence, the installation of 18-meter wide exterior steel plates and 13-square meter steel sheet eaves. By embracing shipbuilding and shipping technologies, the everyday was converted into the exceptional, with a “wow!” effect. The possibilities of architectural design were pushed passed their limits.
▼夜景，night view © SATOH PHOTO
▼剖面效果图，CG Cross section © Nikken Sekkei
Facility Name : Onomichi City Hall
Location : Onomichi City, Hiroshima Prefecture, Japan
Client : Onomichi City
Site area : 7,748.74 m2
Building area : 4,156.07 m2
Total floor area : 14,496.54 m2
Maximum height : 22.75m
Number of floors : 1 basement, 5 floors
Structure : Steel structure; Partially steel in reinforced concrete structure;
Construction period: October2017 – August 2020