Cold comfort: Ice system expected to save green, be 'green'

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Friday, August 1, 2008
— Janesville high school students and staff will endure just one more year without air-conditioned classrooms.

A new cooling system now being installed is scheduled to start pumping out cool, dry air in fall 2009.

And taxpayers will foot the bill, right?

Yes and no.

District officials expect to save on costs to heat and cool the schools, even though the referendum project now under way is adding substantial amounts of square footage.

The new cooling systems will use lower-cost electricity at night to make ice, and then use the ice to cool the air during the day.

A 2006 study by North American Mechanical showed substantial savings when a modern heating/cooling system was compared with the outmoded systems in place at Craig and Parker high schools—even with the addition of building-wide air conditioning.

The 2006 calculation for April through October at Parker High School alone indicates:

-- Total building electricity use without ice storage: 1.84 million kilowatt hours, costing $170,194.

-- With ice storage, 1.8 million kilowatt hours, costing $152,001.

-- Estimated savings: $18,093.

Officials said savings would be more than the 2-year-old calculations because energy prices are higher.

Modern electronic controls are also a big part of the energy savings. They're expected to monitor each room and use only enough warm or cool air to keep rooms comfortable.

"Green"-minded taxpayers might be wondering why the project isn't using geothermal energy—boring wells into the ground to take advantage of underground temperatures that are cooler in the summer and warmer in the winter.

Geothermal was considered during planning for the 2006 referendum. But engineers determined it would have been cost-prohibitive.

For geothermal to work, much of the older parts of the schools would have needed new ductwork, which would have been prohibitively expensive, according to engineering estimates.

Also, geothermal requires a heat pump in almost every room, and many rooms would not have space to accommodate the pumps, officials said.

A newly built school, in contrast, could be built to accommodate a geothermal system.

The ice-storage system required new piping, but not everywhere. Parker already had chilled-water piping in 60 percent of the building. It was installed when Parker was built, but it was never used because it was thought, at the time, that it might someday be needed, officials said.

Ice storage in and of itself isn't an alternative energy source, but it does have a "green" effect, according to Alliant Energy.

Here's how that works:

On muggy, high-demand days, the power company often has to fire up "peaker plants" to handle the heavy daytime use of electricity. Conventional air conditioning, used during the daytime, adds to that need for extra power plants. But making ice at night spreads out the demand for electricity and leads to less need for peaker plants.

Note to consumers: Running your dish- or clothes-washing machines at night has the same effect.

Craig and Parker also are getting some passive "green" technology: All new windows, with double thermal panes that sandwich blinds between them.

And yes, the windows can be opened.

Last updated: 10:05 pm Thursday, December 13, 2012

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