Official in Shanghai's Luwan District hope to have planted gardens on 13,000 square meters of roofs by the end of this year in an attempt to cool down buildings and save energy.

Similar projects are also underway in Huangpu and Jing'an districts as well as Pudong.

A bird's-eye view of the garden on top of Minli Middle School. More such rooftop gardens will be built in the city to cool down buildings.

"We will first encourage companies to increase the use of rooftop gardens by offering preferential policies," said Gao Xiangwei, a greenery official, without explaining what breaks companies will receive for planting a lawn on the roof.

Officials said a few plants and a little grass on top of a building can lower the temperature inside, which reduces the use of air-conditioning.

Garden experts conducted tests on various buildings around the city and found that those with a roof garden were 3 to 4 degrees cooler inside during the summer. There are about 200 million square meters roofs in the city, but only about 350,000 square meters are covered with greenery.

With temperatures in the city rising over the past 20 years, planting gardens on top of buildings is one of the most effective ways to free people from stifling heat, officials said.

Planting gardens on top of a roof is also much less expensive than creating new parks and greenbelts. "But the function will be very great," Gao pointed out.

In addition to reducing indoor temperatures, rooftop gardens can slash the amount of electricity used on air-conditioning by about 20 percent, while also purifying the air and reducing noise.

(Shanghai Daily July 20, 2006)