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Rainwater Connections

New building brings fresh water back to townspeople

Kugayama1
Photo: Takumi Ota

The Kugayama South Gate Building is located in the west part of central Tokyo, near the Kugayama railway station. The area is rimmed with greenery, and shows reminders of the area’s past hilly countryside. South of the station are waterways like the Kanda River and the Tamagawa Aqueduct. To the north, there’s a trace of an old pilgrimage trail.

For a modern commercial building, Ryuichi Sasaki, principal of Sasaki Architecture, Tokyo, says one of the key demands is to maximize profit by compressing common space and make way for as much tenant space as possible. On the other hand, he says, analysis showed that underneath the modern-day cityscape there were generations of relationships between the water, greenery and people. “Finding out how our new building could communicate with this site’s uniqueness was the starting point of the design,” Sasaki says. “We aimed at synchronizing these different values in one commercial building.”

Site Interaction

The rapid development of the suburbs has covered the ground with concrete, and transformed rivers into nothing more than huge ditches. The water level is too unstable for the natural habitat to grow, leaving people to stay away from the water. “We miss the way we had previously interacted with water,” Sasaki says. “We miss the balance and beauty that Mother Nature originally had.”

Situated on a tight, irregularly shaped site surrounded by two roads, the 10,264-square-foot, three-story Kugayama South Gate Building faces the gateway to a shopping lane, which opens its two sides to the public. According to Sasaki, the shopping districts have been partaking in greening campaigns the last few years, and are areas actively engaged in tree planting of each building and planting in front of the road.

Photo: Takumi Ota

Trees and Nature

The tree is one shape found in nature, and everywhere in the water cycle. Branches, roots, veins, rivers and roads, tree shapes are a universal solution of nature to reach as much areas as possible while minimizing resources. “Another advantage is that only a simple set of codes is enough to realize a complex system, because the shape itself is a fractal,” Sasaki explains. “Our solution is to take that shape onto our building, not only as an icon, but as an integral and functioning part of large-scale water cycle that will grow over time and blur the boundary between art and nature. This will best symbolize visions of nature-loving people.”

The Kugayama South Gate Building façade is characterized by the combination of two main elements: aluminum panels and tree shapes. The tree shapes work as a rainwater drain, which provides support for the plants, and at night, lights up the building. The shapes are made up of H-beams as the tree trunks, pipes as the branches, and wires for plants. Tanita Housingware Co. Ltd., Tokyo, supplied the aluminum pipe, while Natsuha Kameoka at Lighting Sou, Osaka, Japan, did the lighting design.

Together, the shapes provide multiple routes of rainwater drainage to minimize the roof slab height while maximizing rental space. According to Sasaki, the rainwater flows along the sides of the H beams into the basement reservoir, where it is pumped for reuse in the building as irrigation for the plants before being let go into a controlled penetration or drainage system until it reaches the river.

“By using the rainwater drain as main part of the façade design, we aimed to change values,” Sasaki explains. “By openly showing the rainwater—in a symbolic shape of natural water cycle—we strongly visualize how the building works as integral part of that cycle. Townspeople will now be able to enjoy rainwater again.”

Photo: Takumi Ota

Aluminum Façade

The façade features 2-mm aluminum in a bright dip anodized aluminum. The aluminum is electropolished and has a bronze color anodize. “We were looking for something to have a material that reflects the constant flow of the city and season, etc.,” Sasaki says. “We considered metal material and it has original characteristic and light itself.”

The reflection of the aluminum panels showcase the constant flux seen throughout the city in terms of climate, people walking around, automobiles, birds, and more. “Aluminum cladding has a special luster that reflects the town's ever-changing ambience in different times of day or weather to blend the new building in this mature townscape while showing prospect to the coming ages,” Sasaki adds.

One of the challenges of the metal cladding was figuring out how much of the diffuse reflection of light had on the street and town. To come up with the right amount, Sasaki says the glossiness of the metal was tested, with several samples being prepared on the construction site.

The project was completed in October 2017. As the plants grow over the tree shapes, they will continue to evolve for years to come. The windows, supplied by Austell, Ga.-based YKK AP America Inc., are enclosed by the tree shapes to present indoor activity in green frames, in hopes of attracting green-friendly tenants. “We expect to see the changes for the better that this little experiment will bring to the townscape,” Sasaki says.

Photo: Takumi Ota