China: Passive buildings captivate developers’ interest


In 2009, Wang Zhen, a property developer in this northeastern Chinese city, made a risky decision. If it were proved wrong, Wang would lose millions of dollars and his hard-earned reputation.

Wang decided not to have district heating in a condominium that he was about to build. In a city where temperatures often drop below zero in winter, most buildings use the city-distributed system; otherwise, occupants there would freeze.
But families living in Wang’s units didn’t. Instead, they became occupants of the first Chinese passive building. As China’s desire to save energy grows, Wang and other property developers in the country have begun to experiment with this kind of ultra-low-energy structure.

Using super-thick insulation and advanced window technology, passive buildings are covered by an extremely airtight envelope — so that almost no heat escapes and no cold seeps in. The buildings are also oriented toward the sun and equipped with heat-recovery devices. The result: A passive energy home consumes 90 percent less heating and cooling energy than a conventional building in the same climate zone.

“As a big country and a big real estate market, China consumes significant amounts of energy,” Wang said. “But the energy resources we have are limited. Developing energy-efficient buildings is a must for the country. That’s why we want to build passive homes.”
But building passive homes in China was not an easy matter. As the passive home project was the country’s first, there were no examples for Wang to follow. He could not simply replicate international approaches, either. The majority of passive structures built in the West are low-rises, while most Chinese families live in high-rise apartment buildings.

When the indoor air gets stagnant, a sophisticated central ventilation system automatically turns on. Most of the air exchange with the exterior is done by controlled ventilation through a heat exchanger in order to minimize heat loss.

In summer, the ventilation system helps cool incoming air, at the same time recycling waste heat generated from the cooling process to heat water.

All the units of the passive building were sold within a year. By contrast, it usually takes two to three years to sell out the units of a conventional condo building, the property developer says.

Chinese officials also like the design. The central government rewarded Wang’s company with 30 million yuan ($4.8 million) in cash. And the local government of Hebei province has been drafting a passive building development guideline with lessons learned from the project.

Statistics from China’s Ministry of Housing and Urban-Rural Development show that at least 37 passive structures are built or under construction in the country so far.

Still, scaling up the practice remains a challenge. As climate conditions in China vary, strategies used to develop passive buildings in chilly northern Chinese cities may not work for those in the warm, humid south.

“We need to develop and implement the best practices in an economic feasible way to fit different climate conditions,” said Tian Zhen, an associate professor specialized in sustainable buildings at Soochow University.

Pan Zhiming, a building energy efficiency specialist at the Beijing office of the nongovernmental organization Natural Resources Defense Council, agreed. Pan said that because no passive building standards are currently available, Chinese property developers have to pour substantial effort into the project design and construction. Not every developer is willing to do so, Pan said, adding that some companies also find it troublesome to train workers how to construct passive homes.

But Berthold Kaufmann, an engineer at the Passive House Institute in Germany, is eager to help.

“We are on a good way together with manufacturers to get components’ cost lower as soon as mass market and mass production is reached,” Kaufmann said.

“If you ask me how many factories in China are producing windows for passive homes, the number is only five. But if one starts, the others will follow. Already, some Chinese companies traveled to Germany to see passive homes and asked us for help.

“Chinese companies are so fast in developing new products, and construction products are no difference. When China will provide high-quality [passive] building products to the world market, costs will probably decrease to a reasonable level,” Kaufmann said.

For full article, see E&E Publishing

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