Jan 28 2010
Approximately 10,000 gallons of DOWFROST™ Heat Transfer Fluid is enabling a new aqua-thermal system at Saginaw Valley State University (SVSU) located near Midland, Michigan. Built into a 6.75 acre, 2.2 million gallon retention pond along state highway M-84, the closed loop, aqua-thermal heating and cooling system at the $28 million Health and Human Services building is the largest system of its kind in Michigan.
The physical operation of an aqua-thermal system is virtually identical to a geothermal ground source system. As in a geothermal installation, the heat transfer fluid in an aqua-thermal system is circulated through water that is consistently warmer or cooler than ambient temperatures. In the SVSU system, pond water temperatures as low as 40 degrees Fahrenheit (F) will assist in winter heating, while summer temperatures as high as 85 degrees F will assist in cooling.
The fluid circulates through two, 10-inch lines that run from the building to the water. Beneath the water, the lines separate into 2-inch lines connected to 28 heat exchangers, each made up of 14 coils. Inside the new building, a mechanical unit made up of seven pumps will pull thermal energy from the fluid and use it to control the temperature in the 90,000 square-foot-building. The system is designed to deliver 350 tons of cooling or 3 million BTUs of heating.
The university expects the systems to cut heating and cooling costs by about 35 percent a year, an estimated $90,000.00 a year in energy savings – a payback of less than four years on the extra costs associated with an aqua-thermal system compared to a standard HVAC system. Two additional glycol lines have been installed for future building projects. SVSU officials hope to have the building certified under the U.S. Green Building Council’s Leadership for Energy and Environmental Design (LEED) Green Building Rating Program. The system will have no effect on aquatic life in the pond.