Cooling System Takes Advantage of U.P. Weather

It is critical to maintain a cool environment for the NMU computer servers housed in the basement of Cohodas Hall. That used to be achieved with a traditional compressor-based cooling system that ran on a 24/7 schedule. A new system, located on the north side of Cohodas (pictured), was installed as a replacement last summer. It takes advantage of the Upper Peninsula’s relatively lower temperatures and reduces the need to run mechanical equipment.

“The replacement utilizes a free-cooling system, because outside air or the natural environment is used to cool glycol, which acts as a chilled water loop to cool the rooms instead of relying entirely on mechanical cooling,” said Ross Christensen (Plant Operations). “This feature is available for most of the year. When the temperature rises above 50 degrees, the system utilizes mechanical cooling. Another added efficiency feature is that almost all components—outdoor fans, refrigeration compressors, air handling units—are variable speed. This acts sort of like ‘cruise control’ for the system. When mated with digital controls, the temperature can maintain within one degree. By implementing these items, the energy savings are quite considerable over a standard on and off cooling system.”

Kathy Richards (Facilities) said the concept is similar to what has been done for the remaining floors of Cohodas while the air-conditioning is being fixed: taking outside air at night to help cool down the building before the next day.

“The main reason for putting in a new system was the age of the original one. It was something we had to do anyway, so we took advantage of the opportunity to install a unit that is 25 percent more efficient. The cost savings is offset somewhat by the fact we’ve doubled the space in the basement that needs to be cooled. The system used to cool the original server room with all of the racks. Now it also extends to the telecom room and adjacent server room. So the system’s more efficient, but we’ve also expanded the scope in terms of the area it cools.”

John Marra (Technical Services) works in the computer center and said the new system is “a big change from just a year ago when we ran four compressors nonstop trying to keep the rooms cool.”

Retiree Bob Ryan was the project manager for the cooling system replacement.