"Although this is the first massive use of ETFE as a construction material in China, it is a mature technology abroad after being used for dozens of years. We decided on this material after a series of tests," said Toby Wong, another Chief Designer on the Water Cube, from PTW Architects.

Wang said the fluorin content in ETFE makes its chemical nature more stable than glass and in tests it has shown that it can survive a hailstorm. In the event of a fire the ETFE roof of the stadium can let open a crack to dispel smoke from the building. Wong said the designers had fully considered the impact of sandstorms in Beijing. He explained that the ETFE membrane surface is an impossible environment for mildew to survive on due to lack of water. The pillow cladding on the Water Cube is also dust-resistant. The life for the ETFE pillow cladding is 30 years and it can be replaced within hours.

While the construction of the landmark project officially started in December 2003, the membrane structure, with over 3,000 ETFE pillows, was completed in December 2006. The whole project looks set to be ready in October 2007.

Venue for all swimming, diving, synchronized swimming and water polo competitions for the 2008 Olympic Games, the arena, covering a floor space of 80,000 square meters, will hold 6,000 permanent seats and be installed with an additional 11,000 temporary seats during the Games. Spectators will witness 42 gold medals being won at the Water Cube.

The building's architecture has provided an opportunity to use new technologies in sustainable development. It uses solar energy to heat the pools and the interior area, and all backwash water and collected rain water will be filtered and recycled.

The erection of the building's steel constructure was highly complicated as it consists of 30,513 different shafts, which had to be pieced together according to a blueprint without a single mistake.

During the first stage of the unprecedented project, no more than 10 shafts per day could be jigsawed together due to lack of experience. Later, construction workers were able to install over 200 shafts per day. To maintain the high quality of the building, 180 welders working on the construction site had to go through 16 rounds of tests before getting the job.

To meet the latest sanitation standards of the International Swimming Federation, all the swimming pools in the Water Cube will use ozone as a disinfectant, which can effectively remove unpleasant smells in the pool while avoiding skin allergies. An automatic water level system has been adopted, which can save on disinfectant, power and refilled water by up to 50 percent.

Another water-saving technology used by the Water Cube is that filtered and sterilized waste water will be used to flush toilets, clean garage floors and water the grass outside the stadium. Another 4.5 tons of water will be saved using this technology each year.