By Deborah Snoonian, P.E.
When the Guangdong Tobacco Company solicited proposals for a new headquarters last fall, the company asked architects to incorporate measures for sustainability. The Chicago office of Skidmore, Owings & Merrill (SOM) took the project as a challenge, submitting a design for a 300-meter tower that the firm says will require no net energy to operate. Known officially as the Guangdong Tobacco Tower, but informally called the Zero Energy Tower, SOM’s proposal is among three finalists. A winner is expected to be announced shortly.
"We have been doing a lot of research into energy efficiency for tall buildings," says Gordon Gill, an associate partner at SOM, who worked on the proposal with partner Adrian Smith and engineer Roger Frechette. "We felt this was an ideal opportunity to showcase how a large building could be designed to utilize energy harvested from the local environment."
The tower’s primary facade would face south to take advantage of prevailing winds from that direction, which would drive a series of building-integrated wind turbines located on two separate mechanical floors. The curved geometry of the facade was designed to maximize the power generated by the wind, says Frechette.
This south facade would also be double-glazed and mechanically ventilated, with integrated louvers that would adjust automatically to the sun’s angle and intensity. Ventilated air would be channeled through a passive dehumidification system to remove moisture. Frechette says despite Guangdong’s humid, subtropical climate, calculations showed such a system could be used successfully.
The tower has other energy-efficiency strategies as well. A unique geothermal system would be integrated into the tower’s caissons and connected to high-efficiency chillers that would reduce the size of the mechanical plant by about 30 percent. Radiant slab cooling on each floor would reduce energy used for cooling by 40 percent compared to a conventional HVAC system, say the designers. Underfloor displacement ventilation would further reduce cooling energy and provide improved indoor air quality. Perhaps more important, the improved ceiling heights achieved through these HVAC strategies would allow the architects to fit the building’s program into a tower several stories shorter than originally anticipated, which would shave operating and maintenance costs throughout the life of the building.