One of the world's greenest skyscrapers approaches completion

The 71-story Pearl River Tower, described as one of the most energy-efficient skyscrapers in the world, has reached its topping out milestone on the way to its planned completion later this year. (For those not in the architectural know, topping out or topping off is a ceremony held when the last beam is placed at the top of a building.) With a height of 309.6 meters the 2.3-million square-foot Pearl River Tower incorporates the latest green technology and engineering advancements, the most immediately obvious of which will be a pair of openings in the tower’s facade which feed wind turbines to generate energy for the building.

Integrated Wind Turbines
Designed by SOM, the Chicago-based architectural consultants responsible for the Burj Tower in Dubai, the Pearl River Tower is being built in Guangzhou, China by the CNTC Guangdong Tobacco Corporation. Its distinctive sculpted body is designed to direct wind to the pair of funnel-like openings at its mechanical floors, which are located roughly one third and two thirds of the way up the building. As the wind flows through it pushes the building’s integrated wind turbines to generate power for the building’s heating, ventilation and air conditioning systems.
The shape of the building is designed to ensure the wind turbines will generate power in relatively mild winds from multiple directions. Wind studies conducted by SOM have predicted the turbines will speed up the wind’s velocity two-and-a-half times. Tested in winds up to 140 mph, the turbines are expected to generate up to four percent of the building’s power requirements and will be used to dehumidify the building.
Energy-Efficient Walls
The tower also incorporates a double skin curtain wall on the northern and southern facing facades – which is essentially a pair of glass “skins” separated by an internally ventilated eight-inch air corridor that acts as insulation against temperature extremes. Instead of transferring through to the interior of the building, heat from the sun is trapped in the cavity and rises to heat exchangers on the equipment floors where it can be used for passive dehumidification and supplying hot water. The east and west elevations will feature a triple glazed facade with external shades and automated blinds within the glazing cavity.
Meanwhile, solar panels on the roof of the building provide power to perforated metal window blinds inside the glazing cavities that automatically track the sun and open and close to minimize solar heat. These systems help the Pearl River Tower to cut its cooling needs and let it use an air conditioning system 80 percent smaller than those of comparable conventional skyscrapers. Solar collectors integrated into the building facades also transform the sun’s energy into usable AC current.
Other eco-friendly elements contributing to the building’s energy efficiency include under floor ventilation air, daylight harvesting and a ceiling system that incorporates chilled water piping to cool rooms by natural convection and radiation heat transfer. The building was also meant to have a geothermal system, but the site didn’t generate enough warm ground water for it to work.
While many of these sustainable attributes have been incorporated individually into skyscrapers around the world, the Pearl River Tower design represents the first time that they have been used collectively.
“Pearl River Tower is a special building that stands as a landmark within the Guangzhou skyline,” said Mr. Ye Zhi Ming, General Manager of the Construction Office of Pearl River Tower. “SOM’s pioneering architectural and engineering vision for this office complex has resulted in a sophisticated, environmentally-smart building.”
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