The Building Tradesman Newspaper

Friday, November 06, 2009

Saginaw Valley State University’s unique aquathermal system...

By Marty Mulcahy, Editor

SAGINAW – The 2.2 million-gallon north pond on the campus of Saginaw Valley State University provides a home to bluegill, crappie and other aquatic life, but next year, it’s going to do what no other pond has ever done in the State of Michigan.

An “aquathermal” heating and cooling system that’s being installed at SVSU and linked to its new Health and Human Services Facility is expected to use the pond to chill and heat water for the building’s heating and cooling system, providing overall energy savings of 34 percent compared to conventional systems.

Spence Brothers is acting as construction manager on the project, which began in April. The building is expected to open in August 2010. The job currently employs about 80-90 Hardhats, and that’s about peak employment.

Under construction on the north side of campus, the two-story (plus mechanical penthouse) Health and Human Services Facility “has been about the smoothest job I’ve been on in the last 10 years,” said Spence Brothers Project Manager Brian Keeler. “Everything has gone really, really well.”

The 95,000 square-foot building will contain 13 labs, 12 classrooms and office space. The building will have a number of environmentally friendly features, and is expected to get at least a silver LEED certification.

The Health and Human Services building in itself going to be a nice, but unremarkable addition to the SVSU campus. However, the building’s first-of-it’s kind heating and cooling system is creating quite a buzz, and has generated television and newspaper stories across Michigan.

“We’re getting a lot interest and inquiries from schools around Michigan,” said Jerry Stuart, director of construction for Saginaw Valley State University. “But we have the pond, and it’s a resource a lot of other places don’t have.”

What’s so special about the pond? Nothing really. It has 6.75 acres of surface area, has an average depth of 13 feet, and sits 1,025 feet from the new building.

During the project planning, SVSU assistant vice president for campus facilities Steve Hocquard decided to pursue using the pond – which he termed “a very efficient energy absorber” – to supplement the conventional heating and cooling system for the Health and Human Services Building. The aquathermal system can also be expanded to serve other buildings on campus.

Underground between the pond and the Health and Human Services Building run four 10-inch main polypropylene tubes containing some 10,000 gallons of “Dowfrost,” –  donated by Dow Chemical – which is a propylene glycol product. The system involves the sinking of 28 “skids” into the pond, each containing 14 heat exchange coils. The system works to heat and cool the building by transferring heat through an underground loop to the coils submerged in the pond.

In the summer, the loop transfers the building’s heat, which is absorbed by the pond. In the winter, the loop draws upon the latent warmth of the water to return heat.

Variable speed circulating pumps vary the flow of the glycol according to the building’s needs. The system eliminates the need for individual heat pumps assigned to every room in the building. And, the heat pump system will provide chilled water to the building’s air handling unit and under-floor heating system to maximize comfort in the building.

The heating and cooling system work is being performed by UA Local 85 members working for Remer and their sub, S & J Heating and Cooling. The university says the system will have no effect on the aquatic life in the pond.

Wayne Kerbelis, of Peter Basso Associates, which engineered the aquathermal system, said a software program measures the amount of heating and cooling that’s needed, as well as the size and depth of the pond, to determine the hardware required for the system.

He said the cooling costs of the aquathermal system would normally be “a wash” compared to conventional methods, but the real savings come on the heating end. The heat pump system can save 50 percent in building heating energy costs, compared to a conventional boiler heating system.

A website which performs experiments in renewable technologies, Richard, said the efficiency of water source heat pumps usually win “hands down” when compared to air or ground-based heat pumps. The reason – “most of the time the water at depth has a consistent temperature and hardly varies at all throughout the year.”

It said the reason more people don’t use ponds in their heat pump systems is simple: they don’t have access to a pond.

HEAT EXCHANGER GRIDS await placement at the bottom of Saginaw Valley State University’s north pond. The pond itself was created a few years ago when road builders needed fill dirt for nearby Bay Road, and scooped it out from an open field – with the college’s permission – on the north side of the campus. Photo courtesy Saginaw Valley State University

FITTERS FROM Local 85 and S & J Heating and Insulation prepare two-inch supply/return lines for heat exchanger grids. Photo courtesy Saginaw Valley State University

PIPES THAT ARE PART of Saginaw Valley State University’s aquathermal system, consisting here of six-inch to eight-inch carbon steel, are ready for a weld by Richard Los of Plumbers and Steamfitters Local 85, working for Remer.