Chill factor


Utilizing ice-based thermal energy storage to cool buildings makes both environmental and economic sense.

Chill Factor - Alex Wilson, April 2010

Somehow, cooling buildings with ice seems primitive—harkening back to the days before refrigerant-cycle air-conditioning when we cooled food and sometimes buildings with blocks of ice. But using ice today is one of the most advanced, smartest ways to cool buildings, and the practice is growing.

Ice-based thermal energy storage is finding its way into more and more high-tech green buildings, including the Durst Organization’s recently completed Bank of America building at One Bryant Park in New York City. The growth in thermal energy storage is no surprise once one understands how it works, why it makes economic sense, and why it’s a great environmental solution.

Understanding thermal energy storage (TES)

The basic principle of ice-based thermal energy storage for cooling is simple. Ice is produced at night when electricity is cheap, and that ice becomes the source of cooling energy during the day. Ice works so well because a great deal of heat is absorbed and released during freezing and melting (referred to as latent heat). Materials can store heat both as sensible heat and as latent heat. Sensible heat is stored as the temperature of a solid or liquid is changed. Latent heat is stored when there is a change in phase—in this case between solid and liquid.

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