Two wells as deep as 2,000 meters underground will provide heat for a 7,500-seat gymnasium in winter, the competing venue for the badminton tournament of Beijing Olympic Games, and another 12 wells are used for the cooling system in summer.

The Beijing University of Technology Gymnasium will realize zero emission in the use of geothermal energy, and energy consumption would be reduced by 30 percent, said vice president of the university Zhang Ailin.

It is one of the venues featuring "Green Olympics". Advanced technologies, including water recycling, rainwater utilization, solar photovoltaic power generation and reclaimed water source heat pumps are widely used, according to Tan Xuxiang, deputy director of Beijing Municipal Planning Commission.

Green Stadiums

The University of Science and Technology Beijing (USTB) Gymnasium, the competing venue for judo and taekwondo, boasts the world's largest suspended dome ceiling measuring 93 meters in diameter.

The highlight of the USTB Gymnasium lies in the installation of 148 optical fiber light pipes that are 530 mm in diameter. On days with strong sunlight, the pipes will be able to meet the lighting needs for sports training in the gym. At night, the pipes will transmit light through the roof, creating an attractive nightscape.

The National Stadium, known as the Bird's Nest for its unique latticework of interwoven steel, is considered a template for water conservation, with 70 percent of its supplies coming from recycled water.

"Recycled water will be used to wash the racetrack and water the plants around the venue," said Li Jiulin, chief engineer in charge of the stadium construction.

Through the system, rainwater that falls on the stadium's roof, playing field and its more than 20,000 square meters of surrounding area will be collected and channeled to a 12,000-cubic-meter pond, before going through three screens of filtration to clear harmful elements.

The National Aquatics Center close to the Bird's Nest, or the Water Cube, also features energy conservation.

It is able to collect millions of liters of rain, bathwater and waste water from swimming pools annually to wash the ground, flush toilets, supplement the water supply for the cooling tower and water plants around the venue.

Its blue bubbling translucent exterior, also a part of the Water Cube's environmental design, is said to allow in more sunlight to heat the swimming pool and save thermal loss.