Ice has long been used for space comfort conditioning. In the early nineteenth century, ice was placed in air ducts to cool and dehumidify warm air blown by fans. I recently saw such a system that was still in use in the Hungarian Parliament building after more than a century of service. The ice in that system was harvested from Lake Balaton in the winter and placed in the air ducts when needed for summer cooling.Since harvesting and year-round ice storage is not common these days, mechanical refrigeration is used to make ice, often at night when electric rates are lower. This ice is stored, and when cooling is needed water is circulated through the ice storage area and then distributed at about 34F (1.7C) to provide space cooling, although lower temperatures can be used with appropriate fluids.
Ice thermal storage has two potential advantages. In addition to the use of off-peak ice making, an ice storage system can reduce chilled water flow requirements by half. A traditional chilled water system using 44F (6.7C) supply and 54F (12.2C) return will require 2.4 gallons per minute (gpm) of chilled water for each ton-hour of refrigeration. An ice storage system can supply chilled water at 34F (1.7C), reducing the required chilled water flow to 1.2 gpm.
| Location | Ice Storage Capacity | Serves |
| Cosmo Square, Osaka, Japan. Joint venture by Kansai Electric Power and Osaka Gas | 29,300 ton-hours 103,000 kWh | Ice storage part of central plant serving six buildings in Nanko, Osaka, Japan, including the World Trade Center and the Asia Trade Center. Steam and hot water also provided. |
| USF&G Office Complex Baltimore, Maryland | 5500 ton-hours 19,360 kWh | Cools six office buildings in the headquarters complex for the USF&G Insurance Corporation. Uses ammonia as refrigerant. |
| Chauffage Urbain Prodith Lyon, France | 8530 ton-hours 30,053 kWh | Cools 4.3 million sq ft (400,000 sq m) of office space in conjunction with traditional chilled water system. |
| Unicom Thermal
Technologies Chicago, Illinois | 66,000 ton-hours 232,300 kWh | Serves commercial customers in Loop area of downtown Chicago. Plant located next to Palmer House Hotel. |
| Montgomery College (2 systems) Rockville & Germantown, Maryland | Each system: 2,440 ton-hours 8,590 kWh | Each system cools five classroom buildings. Uses ammonia as refrigerant. Rockville system to be expanded to serve 17 buildings. |
| San Antonio City Water
Board San Antonio, Texas | 19,300 ton-hours 62,288 kWh | Serves 21 customers, including Alamodome. Built 1993. |
| University of Miami Miami, Florida | 3,660 ton-hours 12,883 kWh | Supplies chilled water to 13 campus buildings |
| Johns Hopkins Applied
Physics Laboratory Laurel, Maryland | 8,400 ton-hours 29,568 kWh | Built in 1988. Cools four office/laboratory buildings. |
| Johns Hopkins University Baltimore, Maryland | 11,200 ton-hours 39,420 kWh | Cools main campus. |
| Homesavings of America Irvindale, California | 13,600 ton-hours 47,872 kWh | Serves five headquarter buildings of Homesavings of America. |
| Lee College Baytown Texas | 5,535 ton-hours 19,483 kWh | Part of a central district cooling system serving 30 buildings. Shifts 760 kW load to off peak for ice building. |