SHANGHAI - Shanghai now has the world's most energy-efficient building, thanks to the Hamburg House, the German city's independent pavilion at the Urban Best Practices Area at Expo 2010 Shanghai.

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Hamburg's mayor Ole von Beust was in Shanghai on Monday to mark Hamburg Day and promote the city's building concept known as the passive house, a concept widely applied in Hamburg's model of its environmentally friendly community Harbor City.

"As the first certified passive house in China, Hamburg House possesses great prospects," said Beust. "Although the building is a little more expensive to build at the beginning, much more will be saved in the long term, and it can adapt to all climate zones in China."

Themed "Home of Hidden Energy", the exhibition showcases benchmarks for ecological construction. The highest-level environmental technologies were used, including a building shell that reduces air-conditioning energy requirements, and an energy supply ensured through geothermal heat, groundwater refrigeration and solar energy.

The house also offers a fresh-air supply, ventilation and exhaust provided with recovered waste heat, all of which were designed with Shanghai-specific climate conditions in mind.

"Hamburg House cost 4.2 million euros to build, half of which came from the Hamburg government," Beust said.

According to the exhibitors, the passive house costs 10 percent more to build than a normal house.

The primary energy requirement of the Hamburg House is less than 50 kilowatt hours per square meter per year. In comparison, Germany considers a primary energy requirement of 360 kilowatt hours per square meter and more to be normal for newly constructed office buildings.