open issue - Plumbing Engineer

pe01_pgs_065_072rev_Layout 1 12/27/11 9:23 AM Page 65
‘Aqua’ changes Chicago skyline
Chicago’s high-rise skyline is forever
changed. Under construction for four
years, the 82-story, 1.9 million-squarefoot
Aqua building in Chicago’s downtown
area is now one of the city’s most
prominent jewels.
The Aqua — built by developer James Loewenberg
of the Magellan Development Group, with design
by Jeanne Gang, FAIA, of Studio Gang — is now a
28-acre Lakeshore East complex on the old Illinois
Central Railroad yards along Lake Michigan. At its center,
the Aqua Tower surges high above the surrounding area.
Gang’s alluring design includes a residential tower,
which rises from a mixed-use podium at its base. All told
the entire project, from land to furnishings, required an
investment of $4 billion.
The design team devised ways to make Aqua energy
efficient through sustainable strategies that enabled the
developer to apply for LEED Silver status. Loewenberg
admits that green wasn’t the first thing on his mind at the
beginning of the process, but, because of Chicago’s strong
environmental laws, he soon thought, “We could make
this building green. We were already heading in that direction,
and I wasn’t even aware of it.”
Gang, who has incorporated energy-saving features into
a number of her previous projects, was delighted.
Concrete and glass
In a city known for its rectilinear skyscrapers, Gang
introduced dramatic curves by wrapping the tower with
sinuous concrete balconies. The building’s plan reserves
floors four to 18 for The Radisson Blu Aqua Hotel, which
opened in late 2011, with 334 rooms and suites. Floors 19
to 52 will have 474 rental apartments. The remaining
upper floors provide space for 264 high-end condos, with
penthouses on floors 80 and 81.
Gang designed the balconies for sun-shading, making
them deeper on the south than on the north. As many balconies
as possible were placed next to living rooms, thus
forming visual extensions of the living spaces.
While the concrete decks cut solar load on the glass
facades, the architects left certain glazed areas exposed —
organically shaped expanses of wall they call “pools” —
for interiors where balconies aren’t needed but direct sunlight
is welcome. To reduce solar load on the exposed
glass, Studio Gang conducted sun pattern studies that in
turn led to its specifying six different types of glazing. In
addition to low-E coatings, the firm selected reflective
Aqua building
glass for the exposed parts of the east and south facades.
Studio Gang acknowledges that the concrete balconies,
which are extensions of the floor slabs, shed Btu in the
winter, much like fins on an air cooled engine. The idea of
adding thermal breaks between the indoor and outdoor
portions of the slabs was considered, but it proved too difficult.
In terms of overall energy use, the heat loss in the
winter is more than offset by summer savings from shade
provided by the balconies and the use of reflective glass in
the “pool” areas.
Inside the dwelling units, the architects selected materials
and equipment with sustainable features, such as bamboo
for the floors. Low-flow plumbing fixtures were
selected to cut down on water use, and Energy Star-rated
appliances were installed.
Mechanical bliss
Heat for the 870-foot tall building comes from four,
12,800 mbh gas-fired boilers that feed a 10-inch riser. Two
1,030 gpm pumps are used to circulate the water, while
another pump is on standby. The boilers are also used to
fire indirect water heaters to supply nearly the entire
building with domestic hot water. The upper condominium
floors have individual gas-fired water heaters.
“That 10-inch main supplies three risers for the whole
building,” said Dan Krebsbach, VP of Advance
Mechanical, which is based in Arlington Heights and kept
between 30 and 40 union workers on the Aqua job for
Continued on page 66
Plumbing Engineer January 2012/Page 65