'Skyscraper of the Year' completed in Chicago

James McHugh Construction has officially completed construction on Aqua, the Chicago high-rise that was named 2009 Skyscraper of the Year by international building database Emporis. Aqua beat out over 300 competitors worldwide for the honor, thanks in no small part to its no-two-alike undulating concrete balconies. It turns out, however, that there’s more to the 82-story tower than just good looks.

There were several challenges that needed to be overcome in the construction process. Because of the building’s proximity to Lake Michigan and the Chicago River, it was necessary to continuously remove groundwater from the construction site. To provide a secure foundation, crews had to fill in over 1,100 linear feet of abandoned underground freight tunnels beneath the property. The balconies also provided a challenge - while each one was unique, they also had to be poured in a reasonably time-efficient manner, so the team could stick to their schedule of pouring one floor every four days. They managed this by using light-gauge steel and brackets to create easily-laid, reusable forming edges for their balcony forms.

The balconies range from zero to eight feet in depth, and were inspired by the striated limestone outcroppings that are common throughout the Great Lakes. Besides providing aesthetic appeal, the balconies also diffuse wind gusts, and cut down on the need for air conditioning by shading the occupants from the sun. The building’s exterior even received an award from PETA, as its irregular, broken-up appearance will supposedly keep migrating birds from flying into it.

Other environmentally-friendly features of Aqua include the use of green building materials, public charging stations for electric cars, and an 8th floor terrace that doubles as a green roof.

"Aqua represents a real step forward in what architects and contractors can do with concrete, from a design standpoint," said Dave Alexander, McHugh's senior vice president. "We feel this building marshals a whole new era of innovation in Chicago architecture and construction."

The highrise contains condominiums, apartments, retail space and a hotel.