For several months in
2008until the World Trade Centers 1,776-ft-tall
Freedom Tower is finisheda planned 945-ft-tall Manhattan
skyscraper might rank second in height in New York City to the
1,250-ft Empire State Building. But forget stature. The team
for One Bryant Park, just starting construction, is far more
excited about how green it might be.
shaped by columns that slope in one direction and in principal
As planned, the 2.1-million-sq-ft
office tower will have all the usual bells and whistles of
a high-performance skyscraper and then some. A proposed anaerobic
digester plant to produce methane from food waste and a green
roof may not materialize. But the building is on course to
have a 4.5-MW cogeneration plant; night ice production; rain,
stormand groundwater capture and use for heating and cooling;
underfloor air distribution and more. The features could slice
$3 million per year off energy bills.
With an air-handling system that
filters 95% of particulates, this building is going to clean
up the citys air, says Robert F. Fox, principal of the
projects local Cook+Fox Architects. And it will have
no stormwater discharge to the city. The plan is to capture
4 ft of annual rainwater expected to fall on the two-acre
spite of all-glass facade, annual energy bills are expected
to be $3 million less. Steel frame will precede core construction.
Scott Frank, associate partner
for the buildings local consulting engineer, Jaros,
Baum and Bolles, calls the water conservation measures unique
to a tall building. Tanks for the water-capture-and-reuse
system will be on different floors of the building, utilizing
gravity feed and minimizing pumping, he says. The team is
even seeking city approval for waterless urinals. That would
save 3 million gal of water per year, says Frank.
The 51-story building, with a seven-story
podium that extends beyond the towers 40,000-sq-ft footprint,
is shaped like a giant crystal, with origami-like folds in
its all-glass facade that create facets. Offices will have
9.5-ft ceilings within a 14.5-ft floor-to-floor height, which
includes raised floors. The southeast face will have a double
glass wall to vent solar heat gain out the top.
The building has a structural steel
perimeter frame and a structural concrete core. The facade
folds resulted in only one totally vertical perimeter column,
says Edward M. DePaola, principal in charge for the local
structural engineer, Severud Associates. All others slope
at different elevations. The complexity of the sloped surface
is minimized by columns that slope in one direction and only
in principal planes, says the engineer.
Unlike most New York City high-rises,
the steel will lead core construction. This strategy was developed
by Severud in the 1970s, but never implemented in New York
until recently, says DePaola.
The construction manager selected
the approach because frame construction is about one-third
quicker, says Joseph L. Ross, executive vice president of
Tishman Construction Corp. of New York. Tishman also is using
the approach on Seven WTC and says the strategy relies on
the use of climbing forms, which allow the core to keep pace
with the steel.
Bank of America, which is the co-developer
with the local Durst Organization, will occupy about half
the building. Durst is the owner of the neighboring Four Times
Square, considered the nations first green
speculative office tower when it opened in 1999.
Fox, who was also the architect
for Four Times Square, says One Bryant Park could not have
happened without its neighbor. But One Bryant Park is
a dream project by comparison because it has the commitment
of not just the developer, but also the main tenant, he says.