Cooling Buildings With Thermal Energy

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. Thermal energy storage makes economic sense and seems to be a great environmental solution. The concept 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.

Consider this example: If a building’s cooling load is 100 tons, during times of peak afternoon cooling requirements in the summer it will take as much as 100 tons of cooling to maintain comfort. Without energy storage, that building would need a 100-ton chiller to meet that peak demand. With energy storage, however, ice is available to meet that peak load so the chiller’s work can be spread throughout the day and night, meaning that a much smaller chiller can provide the building’s cooling needs.  Energy cost and productions problems solved by ice cubes.