TES Spells Savings

The owners of Shell Point, a retirement community near Ft. Myers, Fla., had a problem. It cost them nearly $1.13 million a year to power the 60-plus buildings on their campus. Several new chillers and thermal energy-storage (TES) systems however, are making a very nice dent in the community's energy bill.

The retrofit involved the installation of two 100-ton chillers and a TES system to provide cooling for the village's church and assembly hall. Although the new system cost an additional $136,000, compared to a traditional cooling system, energy costs at this location have been cut nearly in half.

The TES system stores 972 ton-hours of ice at night during off-peak hours. The stored ice is then used in conjunction with the chillers to air-condition the facilities during the day. As a result, approximately 2.71 cents per kWh have been shifted to off-peak hours, plus an additional $8.30 is saved for each kilowatt of demand that is avoided. Combined with a $50,150 rebate from Florida Power and Light, Shell Point owners are now looking at a payback of less than two years.

Additional benefits of the campus-wide retrofit have also been reported, notably better indoor-air quality and occupant comfort. Prior to the installation of the new equipment, Shell Point's senior apartments suffered from high relative humidity. Because the new TES system supplies lower temperature coolant to the air-handler coils, humidity has been lowered. Mold and mildew problems have also been greatly reduced.

Additionally, the new cooling system has also proved its worth in maintenance, with average annual upkeep costs of $35,000 dropping by almost 90 percent.