An interview with Yutaka Hikosaka, architect and designer of Japan’s technologically advanced pavilion at World Expo 2010 Shanghai, China.
Editor’s note: This interview with Mr. Yutaka Hikosaka was conducted by Ms. Kikuko Tagawa, executive director of IFAI Japan, on March 8, 2011 in the offices of Taiyo Kogyo Corp., Tokyo, Japan. Hikosaka was the architectural producer of the Japan Pavilion at the World Expo 2010 Shanghai. He is an architect (member of The Japanese Institute of Architects), and the president of Space Incubator Inc. In addition, he is maestro of Beijing De Tao Masters Academy and a guest professor at East China Normal University. Also present at the interview were Mr. Shinji Nanami and Mr. Jun Kitamura, both of the Design section of Advanced Structures Division of Taiyo Kogyo.
At World Expo 2010 Shanghai (“Better City, Better Life”), which ended on October 31, the Japan Pavilion presented a 100m x 50m x 24m dome with a roof made of steel-framed ETFE film: architecture with an organic image. Putting the emphasis on “eco,” one of the main features of the structure is its use of photovoltaic membrane; ETFE film panels with photovoltaic (PV) cells are placed in a checkerboard pattern on the roof. Air is brought in between the two ETFE films to form a pillow, and amorphous silicon PV films are put inside of the ETFE film. The ETFE film pillows are then placed onto the steel frame.
Amorphous silicon PV film is thin, lightweight and flexible. The power generation by this system is 37kW at the maximum, which covers approximately 5–10% of the electricity that the Japan Pavilion uses. The ETFE film was made by Asahi Glass Co. Ltd., Tokyo, and the PV cells by Fuji Electric Systems Co. Ltd., Tokyo; the pavilion roof was constructed by Taiyo Kogyo Corp., headquartered in Osaka. With another unique feature—an “Eco Tube” system that allows in sunlight and wind and accumulated rainwater—the Japan Pavilion became an experiment in environmentally benign architecture, searching for ways to lower environmental loads. In addition, mist generators on the building’s top spray to cool the air, further reducing the building’s heat gain.
Kikuko Tagawa: What inspired the concept of cushion panels for the exterior cladding of the Japan Pavilion?
Yutaka Hikosaka: Ah, it is very difficult to talk in brief. First, I must say I was asked by so many Chinese people which animation character was the model for this pavilion with a unique shape with horns. I realized that Japan is considered an “Animation” country. Actually this building has nothing to do with any characters in Japanese animation. (Laughs.)
I wanted to make it organic, or biomorphic. The concept of the Japan Pavilion is “eco-breathing architecture,” to accord with the Shanghai Expo theme: “Better City, Better Life.” I wanted the pavilion to make an impressive image by its form and by its color so that it remains in people’s minds.
The Japan Pavilion was the biggest among all the foreign pavilions. The organizer for this pavilion wanted a large inside volume for display, so I thought it should be a big domelike shape or square shape. I produced the Japan Pavilion at World Expo 2005 in Aichi, Japan using bamboo. I wanted to start from there and develop it in a similar shape with a new material and new technology.
In Aichi, the building blocked the light to reduce energy use. However, for this pavilion, I chose a new energy generating concept, photovoltaic cells.
It is nicknamed the “Purple Silkworm Island” or “zi can dao,” and has the shape of silkworm larvae, exciting the people’s imagination that something is about to be born or something comes soon. I wanted to incorporate that kind of message. As you can see in the picture, there is a little part added to the main body, indicating that a new life (or energy) is just born.
As for the color, it is between light purple and crimson, a very noble color both in China and in Japan. Purple goes well as a contrast with the surrounding site greenery, and it goes well with the color of the PV cells as well.* Also, the color changes slightly with the changing of daylight, as does a living creature.
Jun Kitamura: The inner ETFE, which is the same crimson/purple color as the pavilion, blocks the light 99.99 percent.
Shinji Nanami: This would be the first application of this technology in the world. The outer ETFE is transparent so that it allows the sunlight to reach the PV cells.
Tagawa: How do the Eco Tubes work? What function do they provide to the working of the pavilion?
Hikosaka: There are six vertical apertures, three with the solar chimney, in the pavilion. Each tube is like a chimney and connects with the space under the first floor. So the space in the Eco Tube and the space beneath the ground floor is “outside,” where air can circulate. In a traditional Japanese house, there is a space beneath the veranda and the floor. The air circulates and produces natural ventilation and a cooling effect in summer and warming effect in winter. With the Eco Tube it is the same idea.
The upper part of the building is a display area, so it is OK to be dark, but at the first floor, we needed some light; the Eco Tubes allow in light to this lower level.
Rainwater goes into the Eco Tube and accumulates and then circulates to be used in the rooftop sprinklers. The surface of the outer ETFE layer is coated with TiO2, and the sprinkled water reduces the temperature of the building. This concept also is taken from a traditional Japanese idea of sprinkling water over a gateway at a traditional Japanese house for a cooling effect in summertime.
The vertical structure of the Eco Tube supports the large membrane roof. It provides air, water and light to the main organs of the building like blood flowing in our body.
Additionally, one of the important things regarding environmental issues is lightness of weight, or you may say “diet building.” Saving energy after construction is important, but it is also important to build (and dismantle) a building with less energy consumption. Also, the light weight of the ETFE and PV cells really contributes to this by using fewer trucks, fewer people and less energy to construct.
Tagawa: How does placing the PV inside the ETFE cushions work? Why not place them on the outside?
Hikosaka: This system in a package can work even at the North Pole or the South Pole in those extreme environments. PV is protected by air even in a cold/hot environment or in wind/rain storms. Yes, it is for the protection.
Organic EL PV is more interesting, as it is more flexible. At the time we designed the Japan Pavilion, amorphous silicon type of PV was the only option.
Tagawa: What other applications, building types do you think could benefit from this system of energy design?
Hikosaka: It could be applied to anything. This is made for summer, but it also can be used for winter, with some batting inside as an insulator. Eco Tube is also the same, with a building more than a certain size of the building. This is a kind of system suggestion. Takenaka is considering using this in the future for bus stops with PV-generated electric light. Actually an electric cord is not necessary.
One of the interesting things we discovered with this project was that the air in Shanghai is not clear. Consequently, the air inside the pillow was found to contain a lot of dirt. We are surprised about this. The dirt produced a unique line in the pillow, which was OK.
* In truth, Hikosaka expended a great deal of time and energy to convince the Japanese government officials responsible for the pavilion to go with purple.