IceBank® Energy Storage: Cooling for a Greener, Smarter Future
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U.S. Green Building Council Energy Star ARI Office/Commercial Owner


Shell Point Retirement Village

Shell Point Retirement Village
Fort Myers, Florida

What is energy storage and how does it work? energy storage is a proven technology that takes advantage of low-cost, off-peak electric rates to produce cooling energy for use when electric rates are higher. CALMAC’s ICEBANK® thermal energy storage tanks work in conjunction with a building’s chiller to make ice during less-expensive off-peak hours at night. The ice is stored in the tanks and then used the next day to cool the building during more-expensive on-peak hours.

There are at least three energy storage strategies to consider: full storage, partial storage, or a combination. Full storage shifts a building’s entire cooling load to off-peak hours. The building’s chiller only runs at night to produce ice. The stored ice is used to cool 100 percent of the building’s load the next day. Full storage offers the greatest savings potential and is simple to operate, but requires a larger capital investment than partial storage

With partial storage, IceBank tanks work in tandem with the chiller. The chiller produces ice at night and continues to run the following day, cooling up to 70 percent of the building’s load, depending upon electric rates. The stored ice in the IceBank tanks cools the remaining 30 percent. As a result, building owners can install a chiller that is 40 to 50 percent smaller while reducing energy costs. The smaller chiller and electrical requirements of partial storage lower installation costs, which can be used to offset the cost of the storage tanks.

Click here (PDF, 440 Kb) for more information regarding the energy storage process.

Additional building owner benefits

  • Payback period for partial energy storage is typically under two years. Some owners have received payback in less than one year. Full storage, typically, has longer paybacks. Paybacks depend upon the utility rates.
  • Energy storage systems are demand-responsive, providing further savings opportunities.
  • Lower operating costs increase a building’s property value.
  • The size and cost of air handlers, motors, ducts and pumps can be reduced by 20 to 40 percent, further increasing cost savings.
  • Energy storage can lower humidity levels, which leads to increased worker productivity.
  • Click here for a complete list of building owner benefits.

Misconception: Thermal energy storage is risky. Do you consider your water heater risky? Each hot shower is worth about 20 kW of peak demand. A busy house may have two or three showers operating at once, adding 40 to 60 kW to an electric meter. To minimize investment and operating cost, a water heater and storage tank is installed. The water heater can make and store enough hot water using a small heater (10 kW of demand) to make and store hot water. The water heater reduces demand and saves money with very little risk. A partial storage energy storage system is very similar. Most partial storage systems have a smaller chiller than a building’s peak load requires. The chiller produces ice at night, which is stored in IceBank energy storage tanks. The stored ice is used the next day, along with the smaller chiller, to meet the building’s cooling load.

Centex Building Dallas, Texas U.S.A.

The U.S. Environmental Protection Agency (EPA) and the U.S. Department of Energy (DOE) have created an Energy Star Building Program, which rates energy efficiency in different types of buildings. The Centex building in Dallas, Texas, was awarded an unprecedented 99 out of a possible 100 in the rating system, using only 28.4 kBtu/ft2 yr. The building uses 14 CALMAC IceBank® energy storage tanks and a Trane helical rotary type water-cooled chiller to air-condition the 180,000-ft2 building.


Click here for a partial listing of energy storage projects.

Please click here to contact any of CALMAC’s regional managers for additional information or questions.

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