Electricity in a snakeskin jacket

A flying dragon, a snake encircling its prey, or a watercourse – the stadium in Kaohsiung, southern Taiwan, can evoke a variety of associations in a viewer. It forms a closed mass when seen from afar, but seems to change shape constantly as you approach. Curved concrete arches strung together resemble the spinal vertebrae of a primeval animal, lying asleep in the midst of a subtropical parkland. Overhanging lattice stanchions with white steel pipes spiraling around them support the stadium roof. Depending on your viewing angle, these steel pipes either stretch skyward uniformly, or carry your eyes all around the oval of the stadium. The scales on this reptile’s back have a blue sheen, and 8,844 solar modules embedded between diagonally running pipes form the roof cladding.
This stadium, special in so many ways, was created by the Japanese star architect Toyo Ito. Working with the Takenaka Corporation, one of Japan’s biggest building firms, originally specializing in temples, Ito implemented this new building with 40,000 spectator seats as the main venue for the 2009 World Games in Kaohsiung. The World Games are an international forum for sports that aren’t recognized as Olympic events, with tug of war, canoe polo, parachuting and dragon boating among its 31 disciplines.
The games were held for the eighth time last July, one year after the Olympics as is customary. Kaohsiung, Taiwan’s second largest city with 2.8 million inhabitants, was the venue. The government ordered the new stadium to welcome 3,235 athletes from 90 countries. It is the first stadium in Taiwan that complies with both the standards of the International Association of Athletics Federations (IAAF) and the rules of the Fédération Internationale de Football Association (FIFA). The World Games don’t attract as much attention as the Olympic Games, so Toyo Ito’s stadium generated much less excitement than last year’s Beijing “Bird’s Nest”, the Olympic stadium built by Herzog & de Meuron. That was unfair, because Ito’s building creates an exceptional conjunction of opposites: a closed sports arena that nevertheless opens out to the surrounding parkland and city.

Extensive parkland area

After two years of construction, the stadium was completed in January 2009, but even before the opening ceremony in May, more than 200,000 visitors had made a pilgrimage to this sports facility, which is also an extensive parkland area for Kaohsiung’s residents. Visitors arriving from the downtown area by public transport first travel along a wide boulevard before swinging round onto the forecourt. The tail of the stadium block, housing ticket desks and restaurants, leads them from there to the entrance gates, with the forecourt itself rising up a slight incline to the stadium. When you get inside, the surface suddenly falls away to turn into a grassy slope, opening up a vista of the playing fields. Toyo Ito envisages the public having free access to the field during many events, so spectators can drift freely in and out without having to buy tickets.
Ito compares the roof structure, which curls around the entire stadium and produces solar power, to a living organism. The 8,844 photovoltaic modules are installed on an area of around 13,000 square meters, occupying two-thirds of the large, undulating roof and forming its closure.
Three layers in all – the overhanging framework members, the spiraling steel pipes, and the photovoltaic structure – form the roof. The C-shaped framework members bear the main load. A total of 159 beams, of changing size around the curvature of the building, are installed on the site. 32 spiraling steel pipes wind around these roof frames and interconnect them. They are also important supporting elements for coping with occasional loads as they occur, like earthquake shocks and wind forces.
Up on top, solar module units 2.5 to 3.5 meters wide form the roof cladding. The approximately square, semi-transparent glass-glass modules are held in threes, along with an opaque glass panel, in an aluminum frame. An opaque edging strip allows their width to be varied. Taiwan’s Kinmac Solar, formerly Lucky Power Technology Company, fulfilled the big order to make the modules with polycrystalline cells.
The frames are suspended between two adjacent steel pipes, so certain tolerances between the three-dimensional roof structure and the two-dimensional solar modules are unavoidable here. They are compensated for by folded rubber lips, and the connecting pieces can also be fixed to the pipes in different positions and at different angles.

Peak output of 1.03 megawatts

Located in the south of the approximately 400-kilometer-long island, the port city of Kaohsiung is blessed with an average 2,282 hours of sun each year. “On a cloudless day, the solar power array can provide 80 percent of the electricity required during an event in the stadium,” says Charles Lin, who heads the Kaohsiung building authority.
With a peak output of 1.03 megawatts, the array is expected to produce 1.14 million kilowatt-hours per year, enough to cover the stadium’s operations while at the same time supplying power to a considerable number of nearby homes. Toyo Ito’s stadium meets eight criteria of the “Green Building Standards,” the Taiwanese directive on sustainable construction. Instead of having the wood close to the stadium felled, Ito built the stadium around it. He says all its materials can be reused and were produced locally in Taiwan. Rainwater is collected, the illumination comes from LEDs, and the open structure gives the stadium natural ventilation. In summer, the load-bearing structure admits the south-west wind, ensuring mild temperatures in the stadium. The semi-transparent solar modules that cover the roof area fend off direct insolation. Overall, the stadium only occupies a little more than a tenth of the 18-hectare site. Ito has transformed the remaining area into a park. Cycle paths and ponds, palms and other tropical plants offer the citizens of Kaohsiung a new destination for outings.
The Taiwanese government fully financed the stadium with the equivalent of 103 million euros without any support from the World Games Organization. The people of Kaohsiung are hoping that the exemplary and impressive building will put them on the world map, in the same way as the Guggenheim Museum has done for Bilbao, and that the image of a dirty port city will now be replaced by that of a high-tech center for world trade.
While the city’s residents enjoy the extensive park and the square to the south of the stadium created by Israeli artist Yaacov Agam, the government is working on plans to attract further high-profile sporting and cultural events to Kaohsiung. The life of the Kaohsiung stadium has only just begun. The spectator tiers are roofed with a megawatt of output in the form of semi-transparent photovoltaic modules.