St. Cloud Municipal Athletic Center (MAC)
St. Cloud, Minnesota USA
Customer: City of St. Cloud
General Contractor: Harris Companies
Project Contract: US$1,720,000
Project Manager: Bob Swanger
In a time of tight budgets and soaring energy costs, the St. Cloud Municipal Athletic Center (MAC) in St. Cloud, MN found a way to go “green” and save taxpayer dollars in the process. With the installation of a new GeoExchange System, the MAC uses the earth to maintain the arena ice and heat their facility. By installing this sustainable technology, the MAC will reduce gas usage by 95% and electric usage by 30%. Nearly 4,000,000 gallons of water usage will be eliminated along with the yearly elimination of 300,000 pounds of greenhouse gases.
The MAC has two arenas: the Torrey Arena is original to the facility and was installed in 1972. The second arena, the Ritsche Arena, was installed in 1997. The Torrey Arena was not operating efficiently and needed mechanical repair. In addition, the original arena floor was built using galvanized piping that circulated brine through the floor, eventually causing severe degradation in heat transfer and efficiency. The MAC staff felt they could justify a chiller replacement with energy savings but did not think the floor could be replaced due to budget constraints. Harris Companies met with the arena staff and conducted a preliminary review of the facility and found that the project, including the new floor, would be possible.
The heart of the new mechanical installation is the TRAK International
GeoExchange Ground Source Heat Pump System. The system has four
(60) ton heat pumps dedicated to the source loop providing chilled glycol/water solution for the arena floors, and two (60) ton heat pumps dedicated to the load
loop providing hot water that is integrated into the existing hot water and
domestic hot water systems.
The system was custom designed by TRAK International, a division of Harris, to meet the needs of both ice rinks. The Ritsche Arena chiller system was left in place but tied into the new TRAK system so that it could remain as a back-up system and provide additional capacity if needed during peak load conditions. There are other arenas that use GeoExchange, but this is the only one that captures the waste heat generated and raises the temperature to allow for the elimination of all other heating sources, such as boilers or domestic hot water heaters.
The MAC staff now have a high-performance “green” arena with a new arena floor in the Torrey Arena, a high-efficiency GeoExchange “chiller plant”, a new web-enabled and integrated Building Automation System (BAS) installed by Harris Controls and improved system operation. The new system will save enough electricity to power over 30 homes, enough gas to heat over 80 homes, and reduce greenhouse gas emissions by an amount equal to the removal of more than 100 cars from the road each year. In addition to the energy savings and reduction in water and gases, the project will pay for itself within 15-years and create positive cash flow by year seven.