1. Archive


Frozen water cools buildings, slashes bills, frees up the power grid and cuts pollution.

As the summer swelters on, skyscrapers and apartments around the city will crank up air conditioners and push the city's power grid to the limit - but some have found a cool alternative.

Some office towers and buildings are keeping their AC use to a minimum by using an energy-saving system that relies on blocks of ice to pump chilly air.

The systems save companies money and reduce strain on the electrical grid in New York.

Ice cooling also cuts down on pollution. A system in Credit Suisse's offices at the historic Metropolitan Life tower in Manhattan is equal to taking 223 cars off the streets or planting 1.9-million acres of trees to absorb carbon dioxide from electrical use for a year, according to the New York State Energy Research and Development Authority.

Such a reduction in pollution is valuable in a city where the majority of emissions come from the operation of buildings. Officials said there are at least 3,000 ice-cooling systems worldwide.

Because electricity is needed to make the ice, water is frozen in large tanks at night when power demands are low. The cool air emanating from the ice blocks is then piped through the building. At night the water is frozen again and the cycle repeated.

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, officials said.

The technology is not 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.

Air-conditioning alternative

How it works: Imagine a fan blowing cool air from a block of ice, only on a larger scale. Water is frozen in huge silver tanks and the cool air emanating from the ice blocks is then piped throughout the building.

The benefits: Officials say replacing traditional air conditioners with the ice-cooling system in one Manhattan office tower is as good for the environment as taking about 220 cars off the streets.