SCAD invests in energy-efficient air conditioning

Photo by Charlie Ribbens
Jim Buice, SCAD maintenance superintendent, services the chilled water system at the SCAD Student Center May 25.

By: E. Christina Spitz

Published: Friday, June 1, 2007

The Savannah College of Art and Design is a cool school in more ways than one. In several of its buildings, including Boundary Hall, Montgomery Hall, the Student Center, York Hall and SCAD-Atlanta, the college has invested in distinctive, state-of-the-art air conditioning systems that provide energy-efficient cooling.

An air conditioner’s objective is to transfer heat from one source to another. A chilled water system, one of the systems used by SCAD, utilizes water at an operating temperature of approximately 42-45 degrees Fahrenheit to convey heat from a conditioned space to the outside.

Michelle Peavler, mechanical engineer and principal at Rosser International, an engineering firm that has worked on air conditioning projects for SCAD, explained the process.

“A building is cooled by means of an air handler. An air handler is made up of a fan, cooling and/or heating coils [a collection of pipes that essentially works as a radiator], and a filter … [With a chilled water system], the cold water, usually around 45 degrees Fahrenheit, enters the coil, picks up heat from the air and returns to the chiller,” she said. “The air is cooled down to supply cold air to the space and keep the desired room temperature … The water goes back and forth between the air handler and chiller …The chiller takes in the water coming back from the air handler, which has now warmed up from the 45 degrees to around 55-58 degrees Fahrenheit, and cools it back down. The chiller does this with refrigerant. The refrigerant now takes the heat from the water and makes the water cold again.”

With an air-cooled chiller, such as those used by Bergen Hall (to make cold water for photo development), the Student Center and Boundary Hall, the chiller is outside and releases the heat directly into the air. York and Montgomery halls have water systems with cooling towers, which, according to the Cooling Technology Institute Web site, are “heat rejection device[s], which extract waste heat to the atmosphere though the cooling of a water stream to a lower temperature.”

York and Montgomery halls use a water-source heat-pump system. “Each area within the building is equipped with a heat pump (as opposed to a fan-coil of the chilled water system),” said Rick Sebring, principal engineer at Sebring Engineering, another firm that has worked with SCAD on air conditioning projects. “This heat pump has an integral compressor that operates to transfer the heat from the space into the water loop, which transports the heat to a cooling tower, where it is expelled into the atmosphere via evaporative cooling.”

The systems are efficient in numerous ways. To begin with, they allow for the air conditioning of one room at a time instead of an entire building, saving energy.

Furthermore, a chilled water system can also be used for thermal storage, according to Chuck Hanning, senior mechanical engineer, principal, with Rosser International. In some states, he pointed out, the cost to buy electricity at night is cheaper than during the day. “So if you generate ice at night or chilled water at night, you could use your chilled water [to cool a room] during the day,” he said.

Though the systems are expensive up front, he said, they are worth it.

“If you bought a refrigeration-type unit … for your house, the lifespan on most of those is maybe around 12 years. A chiller’s lifespan is approaching 20 to 30 years,” he explained.

Jim Buice, maintenance superintendent at SCAD, said money also can be saved through heat pumps, which “are efficient because you don’t have to manufacture heat. It is available all the time — you just transfer it.  We can move heat cheaper than we can manufacture it,” he explained.

The systems also are environmentally friendly in that they reduce the number of units on the ground and keep the refrigerant sealed and self-contained.


Spitz is senior publications editor.