Supertall high-rises pose some issues in the HVAC arena. How can you efficiently cool and heat a building that is over 120 stories? Gensler found a way with zoning.
Gensler is the architect working on the 121-story, 2,073-foot tall Shanghai Tower that will be the second tallest building in the world. To re-think the HVAC, they decided to zone the building into 12-15 floor zones so they can develop a better HVAC plan and install a hybrid cooling system.
"There is a certain threshold where it doesn't make sense to put [the chiller plan] at the top so you bring it back to the ground, and you start thinking about the building in zones," said lead project architect Ben Tranel.
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Soaring more than 1,200 feet into the sky, supertall skyscrapers are monuments of engineering prowess, from their structural design to their construction. Less well appreciated is the technology that makes them livable: How exactly do you heat and cool a tower that shoots a half mile into the sky?
In a standard high-rise, it’s mostly a matter of scale: With large enough pumps and heat exchangers, a single system with a cooling tower and chiller plant on the roof can service an entire building. But as a structure approaches supertall status, this one-building, one-system approach becomes too expensive, too inefficient, and too bulky.
“Supertalls are like cities standing vertically,” says Mehdi Jalayerian, an executive vice president for Environmental Systems Design, in Chicago, which consults on HVAC design for supertall towers. “The real challenge is how [do you] get environmental controls and amenities [to residents] as you get higher?”
The answer: Creatively.
Take the 121-story, 2,073-foot-tall Shanghai Tower, slated to become the tallest building in China and the second tallest in the world. Rather than think of the building as a single unit, Gensler opted to parcel the structure and install a hybrid cooling system. “There’s a certain threshold where it doesn’t make sense to put [the chiller plant] at the top so you bring it back to the ground, and you start thinking about the building in zones,” says lead project architect Ben Tranel, AIA, a principal based in San Francisco.
GenslerInterior rendering, Shanghai Tower
Gensler and engineering firm Cosentini Associates, in New York, divided the tower into nine zones, each 12 to 15 floors in height, and fitted it with two chiller plants, one in a sub-basement and the other in a mechanical space spanning the 82nd and 83rd floors. (Each of the nine zones also has its own ventilation system, water heaters, and electrical transformers.) By doing so, the designers eliminated the need for a massive chiller plant in the upper reaches of the building and reduced the load on the pumps at grade.