Council on Tall Buildings and Urban Habitat
 

Aqua Tower Tour


17 December 2008, Chicago

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Looking Up     Click here to see photos of the Aqua Tower Tour.

CTBUH staff had the great opportunity to receive an educational tour of the Aqua Tower guided, by Jim Loewenberg of Magellan Development Group (Owner/Developer for the project), Randy Bullard, Project Manager from contractors McHugh Construction and Mauricio Sanchez, Project Architect from Studio Gang Architects.

The tour started at the east side of the tower in the park at Lakeshore East. Equipped with hard hats CTBUH staff listened fascinated as Mr. Loewenberg explained his latest project, in the creation of an entire urban neighborhood – the 28-acre Lakeshore East, which is the largest parcel of downtown land under development in Chicago. This $4 billion development is located where the Chicago River meets Lake Michigan and will eventually include 4,950 residences, 2.2 million gross square feet of commercial space, 1,500 hotel rooms, a public park and a proposed elementary school. Over one-third of the Lakeshore East master planned community has currently reached completion.


The Aqua Tower will be one of the most striking architectural designs in Chicago with its one-of-a-kind form measuring 874 feet in height. Although it is listed as an 82-story structure, it will actually rise 88 stories from ground level, with six levels of parking below the raised street level of Upper Columbus Drive. The building's eight-story base – which will be topped by an 80,000-square-foot terrace with gardens, gazebos, pools, hot tubs, walking/running track, and fire pit – will offer approximately 140,000 square feet per floor, while typical tower floors will be approximately 16,000 square feet in area. Aqua, which has been designed to meet LEED certification, will feature five levels of enclosed parking and three levels of retail, hotel and amenity space on an eight-story base. The tower will feature 18 floors of hotel space, 30 floors of apartments and 25 stories of condominiums. The reinforced concrete structure is being built atop 305 drilled bell and rock caissons, ranging from 4 to 10 feet in diameter and reaching as far as 112 feet below grade. In drilling the caissons, the project team had to work around more than 1,100 linear feet of Chicago's underground freight tunnels. Studio Gang Architects is the consulting architect for Aqua, Loewenberg Architects is the architect of record, and McHugh Construction is general contractor.

          
Mr. Loewenberg describing his latest project   CTBUH staff on their way up to the 76th floor


A construction hoist took CTBUH visitors up to the 76th floor – viewing en-route the tower’s exterior; a glass façade with undulating balconies that change slightly from floor to floor creating a rippling effect across the façade. Despite the cold Chicago wind, all enjoyed the journey to the top of the tower, with great views out over Chicago. Mr. Bullard explained the challenges faced in constructing the undulating balconies. They were poured in place on top of a table system and shaped by a flexible steel edge that was reused to make the different edge profiles. A robotic survey tool that was used, able to load construction drawings and guide the balcony shapes on site. “At first, we thought they were going to come within a tolerance of 4-5 inches, but it was really dead on,” Mr. Bullard explained. “We’ve found that there’s no variation between what was drawn and what gets laid out.”

Breathtaking views out over Chicago


The tour next took in one of the technical floors, where Mr. Loewenberg and Mr. Bullard described the MEP systems of the tower and how different uses are handled. A highlight of the tour was the visit to a completed apartment, which gave insights into the interior design and enabled study of the cantilevered balconies. Mr. Sanchez explained that the building’s exterior is being composed with approximately 300,000 square feet of glass, with five different types of glass in the window system, e.g. solar glass in those areas where the balconies don’t provide protection from the sun to avoid solar heat gain. Studio Gang Architects decided to use black painted steel balustrades to achieve the effect of them disappearing against the façade. A glass balustrade may have offered greater panoramic views and a translucent space perception but would have boosted the construction cost considerably. Thus the black steel balustrade was considered an acceptable solution.

Each floor plate in Aqua has a different shape at every level. The “waves” of the balconies that provide Aqua's rippling effect extend out as much as 12 feet from the glass curtain wall. According to Mr. Sanchez, the typical floor thickness is 9 inches. However, the balcony thickness varies. “Each balcony begins to slope just 8 inches beyond the column line,” he points out. “So, the further a balcony comes out, the thinner the slab becomes. Every piece of that slab is a different thickness as it contours out from the building edge.”

                              
 Mr. Bullard explaining the construction of the balconies
   
The effect of the black steel balustrade disappearing against the façade    Undulating balconies of the
Aqua Tower


The free cantilever balconies are an important asset to the Aqua Tower. However when a protruded external balcony slab without thermal isolation is cast as an extension of the internal floor slab it creates a classic thermal bridge. The balconies on the Aqua are an extension of the internal floor slab and are treated with an insulating paint to attempt to reduce the heat transfer into or out of the apartments. Over lunch later, CTBUH staff discussed the efficiency and durability of this solution and whether a thermally insulated connector, highly used in Europe would be an appropriate solution taking into consideration construction, cost and its level of performance. Staff noted that there were several methods of avoiding the thermal bridge problem with cantilevered external slabs, typically employed in European construction, that don’t seem to be considered in the U.S.

Towards the end of the tour the CTBUH team gained a first impression of Chicago’s next biggest ballroom, the interior swimming pool, the fitness club and the hotel lobby. As the visitors finished the tour and left site the tower gave a climatic farewell with a ground floor breathtaking view up its rippling façade induced by the cantilevered, undulating balconies.

Our combined thanks go to Mr. Loewenberg, Mr. Sanchez and Mr. Bullard for making this outstanding tour possible and CTBUH look forward to facilitating a further tour of the completed Aqua Tower in summer 2009.

For more information on the Aqua Tower visit
http://www.studiogang.net.

From left to right: Randy Bullard (McHugh Construction), Katharina Holzapfel (CTBUH), Steven Henry (CTBUH),
Philip Oldfield (CTBUH), Antony Wood (CTBUH), Tim Brown (IIT), James Loewenberg (Magellan Development Group), Mauricio Sanchez (Studio Gang Architects), Rich Harkin (IIT)




Picture Gallery
Click an image below to enlarge. Photos courtesy of Marshall Gerometta and Katharina Holzapfel.

           
View Aqua Tower from the Park at Lakeshore East
Mr. Loewenberg describing his latest project CTBUH staff on their way up to the 76th floor
View out of the construction hoist
Mr. Loewenberg on the construction of the Aqua Tower
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View looking north with John Hancock Tower
View looking east over Navy Pier View looking south at Blue Cross Blue Shield Extension View looking south over Millennium Park
View looking west over Chicago River and Trump Tower
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Mr. Bullard explaining construction of the concrete floor slabs
View looking down over Aqua Tower Terrace Technical Floor in Aqua Tower
Undulating Balconies with Swissotel in the background Black steel balustrade disappearing against the façade
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The ballroom
The interior
swimming pool
CTBUH staff
View looking up the Aqua Tower
View up under the entry canopy