'Green curtains' helping to keep buildings cool

TOKUSHIMA (Kyodo) An elementary school in Itabashi Ward, Tokyo, is taking part in an experiment to grow plants covering its outer walls as a way to beat the heat.

Sixth-graders tend the plant bed during breaks from class, checking the progress of cucumbers and dishcloth gourds whose stems extend over a net stretching from the ground to the third floor.

The students at Takashima No. 5 Elementary School have been keeping an eye on the garden plants since the school year started in April.

Itabashi Ward is regarded as an "advanced" locality in a growing "green curtain" movement aimed at setting up nets outside school buildings, public facilities and homes to grow plants. The idea is to block the sun in the summer and keep rooms cool, holding down the use of air conditioners to save energy.

The movement is proving its worth this summer, with Japan seeing a stretch of record-breaking heat.

About 50 schools and a smattering of public facilities in Itabashi Ward are taking part in the movement championed by Takashima schoolteacher Ruriko Kikumoto, 49, which she initiated while teaching at another school in 2002. She got the idea from growing morning glories at home.

"I spent the summer (growing the flowers for shade) almost without using air conditioning," she said.

Kikumoto describes the savings on her electricity bill as "friendly to my wallet."

She also points out that green curtains do not impose a burden on the environment.

Such efforts are spreading. More than 130 elementary and junior high schools in Kyoto are taking part in the green curtain movement.

Yuji Suzuki, head of the nonprofit organization Midori no Kaaten Oendan (Green Curtain Support Group), said the drive can really take off once children "bring it back home." Suzuki's group is striving to popularize the movement centering on schools.

To cut air conditioning bills, officials in Kamiita, Tokushima Prefecture, covered the exterior of the ground floor of City Hall last year with a 45-meter-wide net bearing "goya" vegetables, akin to bitter cucumbers, which are part of Okinawan cuisine.

"It looked cool in its appearance," said Toshiyo Tamura, 57, of the town's general affairs division. Supporters in the prefecture launched a network this year to promote the green curtain drive.

Meanwhile, Minami Ward in Yokohama plans to hold a photo contest on green curtains covering homes.

Green curtains are not only refreshing and cool because they block the sun but also because the water that collects on the leaves reduces the surrounding heat as it evaporates.

Kenichi Narita, a professor of environmental engineering at Nippon Institute of Technology, studied the difference in room temperature caused by the presence or absence of green curtains in a Tokyo elementary school room last year.

He found a temperature difference of 1 degree when the windows of the room were open but found a maximum disparity of 4 degrees when the windows were closed. He also learned that the difference in "reasonable temperatures" rose to a maximum of 6 degrees because the sun warmed the room's floor and walls and prevented the heat from being discharged.