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respectively. The city’s overall energy efciency retrot proect is reducing emissions by more than 1.7 million pounds of CO2
taking more than 160 cars off the road every year.6
CHALLENGES AND
equivalent annually, which is equivalent to The
ice arena upgrades account for nearly 30 percent of the proect’s total carbon reductions.
The indirect NH3 /CaCl2 /CaCl2 system has experienced no
refrigeration leaks to date. urthermore, by selecting NH3
instead of hydrouorocarbon (HC)
refrigerants, like R-507, additional greenhouse gas emissions are avoided.
A breakdown of the costs associated with the ice rink renovation is as follows:
Installation costs. The overhaul of the two ice rinks cost $4.5 million, which the City of Brooklyn Park funded with grants, Heritage Infrastructure unds, bonds sales, and utility energy savings rebates. Installation costs for indirect ammonia ice systems are typically 3.5 percent more than R-22 or HC systems, since the systems usually require additional building renovation costs to address ammonia’s toxicity and mild ammability (e.g., a re-rated room, vestibule on the entrance door to contain potential ammonia leaks, or exterior entrance).
Operation and maintenance costs. Maintenance costs are somewhat lower for an industrial-grade ammonia system than a similar system using R-22 or HC-based refrigerant because of the smaller equipment and increased efciency in its operation. Maintenance costs include compressor oil changes, gasket replacements, and inspections, among other activities.
Costs savings. The citywide efforts to improve energy efciency are saving the city more than $250,000 per year in utility and other operational costs; the ice rink renovations are contributing approximately 25 percent to these cost savings. The citywide efforts to improve energy efciency, which include the ice rink renovations, have an estimated payback period of ust over 12 years.
LESSONS LEARNED The conversion to a new ice rink was a maor undertaking, and with it, the Brooklyn Park CAC faced a number of construction-related obstacles, including nding sufcient space for the new systems, routing piping through the existing building, and working around day-to-day services and operations during renovation.
The Brooklyn Park CAC also had to overcome a challenge related to using the system’s waste heat for other building applications, since as a result of improvements to the energy consumption of the refrigeration system, the waste heat given off by the cooling plant became insufcient to continue to use as a source for many of the heating needs of the building. Introducing new heat pumps not only satised the hot water temperatures required by the facility but it also signicantly reduced operation costs over time.
Other ice arenas have since been upgraded with similar designs using similar advanced control technology and climate-friendly refrigerants. The geothermal connection may be a viable option for some facilities, if local governments can access raw or nished water mains at a low cost. The controls and balancing of the system is applicable to any ice arena in any community.
The CAC’s previous R-22 refrigeration system. Source: Stevens Engineers
U.S. Environmental Protection Agency Office of Air and Radiation (6205T) EPA-430-R-14-008 October 2014
6 See EPA’s reenhouse as Equivalencies Calculator, available at: www.epa.gov/cleanenergy/energy-resources/calculator.html.