New York Skyscrapers Use Ice to Stay Cool
Monday, July 16, 2007
NEW YORK — As the summer swelters on, skyscrapers and apartments
around the city will be cranking up the air conditioning and pushing
the city's power grid to the limit.
But some office towers and buildings have found a way to stay cool
while keeping the AC to a minimum — by using an energy-saving system
that relies on blocks of ice to pump chilly air through buildings.
The systems save companies money and reduce strain on the electrical
grid in New York, where the city consumes more power on hot summer
days than the entire nation of Chile.
It also cuts down on pollution. An ice-cooling system in the Credit
Suisse offices at the historic Metropolitan Life tower in Manhattan is
as good for the environment as taking 223 cars off the streets or
planting 1.9 million acres of trees to absorb the carbon dioxide
caused by electrical usage for one year.
Such a reduction in pollution is valuable in a city where the majority
of emissions come from the operation of buildings. State officials say
there are at least 3,000 ice-cooling systems worldwide.
"It is worth it to do in New York City," said William Beck, the head
of critical engineering systems for Credit Suisse. "If you take the
time to look, you can find innovative ways to be energy efficient, be
environmental and sustainable."
Because electricity is needed to make the ice, water is frozen in
large silver tanks at night when power demands are low.
The cool air emanating from the ice blocks is then piped throughout
the building more or less like traditional air conditioning. At night
the water is frozen again and the cycle repeats.
Ice storage can be used as the sole cooling system, or it can be
combined with traditional systems to help ease the power demands
during peak hours.
At Credit Suisse, for example, the company must cool 1.9 million
square feet of office space at the Met Life tower, a historic building
that was New York's tallest in the days before the Empire State
In the basement, three main cooling rooms house chilling machines and
64 tanks that hold 800 gallons of water each. Credit Suisse has a
traditional air conditioning system, but engineers use the more
efficient system first.
Construction on the system took about four months, and company
engineers say it is extremely efficient.
"The concept is the same, but when you make something mechanical, it
can break, but a big block of ice four floors below grade level isn't
going to do anything but melt," said Todd Coulard of Trane Energy
The company built the Credit Suisse system and is one of several that
work with ice storage.
Trane, the air-conditioning arm of American Standard, also developed a
system for Morgan Stanley's Westchester County offices, and just
completed a new system for its offices on Fifth Avenue.
A new Goldman Sachs headquarters will also have ice cooling. Credit
Suisse is looking at installing the systems in offices around the
globe, but nothing has been decided yet.
Coulard, an expert in energy efficiency, was hired by the company four
years ago to develop the energy services department.
"I've been doing green since before it was cool," he said. "The idea
of not only saving money for large companies, but doing something that
benefits the environment is win-win. It's doing the right thing."
Engineers say the power-saving results from the system are impressive.
And it translates into millions of dollars saved in energy bills for
Ice storage at Credit Suisse lowers the facility's peak energy use by
900 kilowatts, and reduces overall electric usage by 2.15 million
kilowatt-hours annually — enough to power about 200 homes.
At the Morgan Stanley facility in Westchester County, the system
reduces peak energy use by 740 kilowatts and overall electricity usage
by 900,000 kilowatt hours annually.
Both companies received incentives from the New York State Energy
Research and Development Authority under a program designed to improve
the power grid and help businesses reduce operating costs.
The technology isn't for every office space. There has to be room to
install the large tanks. And costs are considerable: Credit Suisse
spent more than $3 million to renovate its cooling system; and Morgan
Stanley's costs were comparable, which means the technology is best
suited to large companies.
"This is for companies that want to go green but that there has to be
other benefits, returns on investments," Coulard said. "It works for
larger companies because their cooling costs are so considerable."