Three gardens, seven meters lower than the ground surface, have been built under the fencing gym of the 2008 Beijing Olympics in order to save energy as cool air comes easily without the help of air conditioner, the Olympic project contractor said.

The gardens, covering an area of 1,200 square meters, could see the underground temperature lower than a normal room temperature, according to a spokesman of the Beijing Construction Engineering Group (BCEG) that designs the gardens.

He said cool air could come naturally with the effect of three dormer windows built on the top of the fencing gymnasium that produces air convection out of air pressure caused by the temperature difference between the gym and gardens.

Both the gardens and fencing gyms are built in the National Conference Center, one of the landmark buildings in the Olympic park in northern Beijing. Covering an total area of 270,000 square meters it will be completed before the end of 2007.

"People in the conference center can feel cool without air conditioner even in the heat of summer," said a BCEG engineer, calling the garden design as a plan of "characteristics and great originality".

How to water them becomes a problem due to the size of the gardens. Zhao Feng, a BCEG technical staff, said the arch bridge-shaped roof of the center could be served as a rainwater recycling container that collected and treated rainwater to water the three large underground gardens.

"Rainfall in Beijing's August can meet the demand," said Zhao, adding without the energy-saving plan the expenditure on water "can be great".

About 380,000 kwh of electricity could be saved annually for the center, experts estimate.

The center will host fencing and air pistol events during the Games scheduled for next August and serve as a home for a major press and an international broadcasting center.

Beijing usually suffers humid and hot weather in August. As the country marks a one-year countdown to the Games, officials and experts have been exploring ways to ease the heat, save energy and bring flower into full blossom though few flower types are able to cope with the heat.

(Xinhua News Agency August 14, 2007)