The "enclosed" offices have got local architects thinking on how to ensure thorough ventilation in high-rises while eliminating potential dangers of "skyscraper hurricane."

"We have never encountered such a situation before," said Huang Xiangming, a chief architect of Tian Hua Architecture Planning. "If we open the windows of an on-flight plane, everything inside the jet will fly out because of the negative pressure. Similarly, windows of skyscrapers are also not designed for opening."

He added, "In case they are opened, people inside will suffer heavy gale and at the same time indoor stuff could 'fly' out of the window, posing a danger to passers-by on the ground."

As a result, most property management companies for skyscrapers - such as Jin Mao Tower, the country's tallest building in Pudong District - have no plans to open windows, for now.

"We still depend on our central air-conditioning system which purifies the interior air every 54 minutes," said Wu Lin of China Jin Mao Group Co.

However, with the Ministry of Health urging "careful use" of central air-conditioners, some office workers in skyscrapers have tried opening windows to a small crevice for ventilation. But architects warn against it.

Xing Tonghe, a chief architect of Shanghai Xian Dai Architectural Design Co, said: "Those randomly unfastened small 'openings' can hardly provide overall ventilation because air convection should be achieved through overall architectural design."

Xing suggests highrises use "double-layers windows, which allow air to flow in through pipes between the two layers of glass so that people only have to open the interior window for ventilation.

Nearly 2,000 local office buildings have central air-conditioners but few are fitted with "double-layer" windows because it's very expensive, he said.

(eastday.com May 28, 2003)