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technology allows the ice sheet to warm during non-use and then automatically cools the ice sheet before skaters return to the ice arena (without affecting ice quality). Making energy saving improvements to an ice temperature control system can sometimes cost as little as $1,000, but significant upgrades usually cost at least $9,000, with a resulting energy savings payback period that is typically several years long or longer. The implementation of improved ice temperature control should be considered in conjunction with implementing automatic capacity control for compressors and installing cooling system pump controls. Arenas that have infrared ice temperature control and/or ice temperature setback are listed below. Arena Contact Person Phone Litchfield Civic Arena Steve Olson (320) 693-2679 Farmington Civic Arena Jim Bell (612) 463-1851 Cottage Grove Arena Dean Mulso (612) 458-2846 Bloomington Ice Gardens Andy Baltgalvis (612) 948-8842 Automatic Capacity Control of Compressors The compressors in ice arena refrigeration systems are sized large enough to be able to handle the initial freezing of the ice sheet. During lower cooling load periods, such as overnight and in winter, the compressors are oversized and waste energy. Many control systems simply cycle an arena's compressors on and off-even when the potential to vary compressor capacity is built into the system. Automatic capacity control of the compressors can provide more efficient operation of the compressors by supplying a more consistent feed of refrigerant at a slightly higher average temperature. The higher temperature allows the refrigeration system to operate more efficiently and use less energy. Additional savings can also be realized by a reduction in an arena's monthly electric demand charge. The electric utility bases an arena's demand charge on the highest power draw over a fifteen minute interval during a given month. The power draw for compressors with a simple on- off cycling control is high because the compressors operate near their maximum capacity whenever they are on. In contrast, automatic capacity control allows the compressors to operate at significantly reduced power draws most of the time. The reduction in monthly demand charges (kilowatt or kW) can be significant, amounting to more than the savings associated with total monthly electric use charges (kilowatt hours or kWh). Automatic capacity control of compressors has long been used by a number of ice arenas in Minnesota. The cost to upgrade an existing refrigeration system with a new control system using automatic capacity control is usually several thousand dollars or more, which typically leads to a long energy cost savings payback time period. However, the most important benefit of automatic capacity control is often the reduction in the personnel time and expertise necessary for day-to-day operation of the refrigeration system. This is because the simple on-off control systems used in many ice arenas often demand significant arena staff time to frequently check on the system and make manual adjustments. The implementation of automatic capacity control of compressors should be considered in conjunction with the decisions to implement improved ice Energy Improvements in Minnesota Public Ice Arenas Project Page 9 Center for Energy & Environment