Last week when the temperature hit 103 degrees, it was still a nice and cool 70 to 75 degrees inside the buildings at the University of Nevada, Reno. That’s because large cooling systems on campus are connected to an underground grid so buildings can share cooling power. If each building depended solely on its own system, a few degrees of heat or cool would be sacrificed when the temperatures reached either extreme.
This underground system includes a network of pipes, valves and pumps—and something John Sagebiel from UNR’s Department of Environmental Health & Safety called, “a lot of really sophisticated controls.” The network, largely underground, has been added onto any time there’s been construction on campus over the last several years so that future buildings can be connected to it. On July 14, the system got a new addition, a central cooling unit that’s expected to slash UNR’s energy bill.
The new unit, which took up two lanes of freeway traffic as it arrived by truck with a police escort, was placed just east of the Ansari Business Building. The unit chills water, which is dispersed around campus to cool the buildings, by piping it through large tanks of R-134A refrigerant.
“That’s the same stuff that’s probably in your car’s air conditioner,” said Sagebiel.
This new equipment will allow for a fully centralized cooling system to go online soon, serving 23 buildings. After more buildings are renovated or built over the next few years, it should serve 28.
Although this will be UNR’s first leap from shared cooling to centralized cooling, centralized heating has existed on campus since 1908. Sagebiel called these two underground systems part of “the invisible campus.”
“I bet you could interview a thousand graduates of UNR, and maybe one of them has seen the inside of this thing or knows it’s here,” he said of the central heating facility, a nondescript brick structure also east of Ansari. “If we put up a big solar array, everybody’s going to come by and look at it. Nobody’s going to look at this.”
Invisible as the system may be, experts predict it’ll yield some noticeable advantages.
“By centralizing, you gain efficiency,” said Sagebiel. For example, UNR runs its centralized heat system using four boilers, the largest of them about the dimensions of an oversized dump truck. When the cold weather starts in the fall, it’s likely that only one of those boilers will be in use, and it’ll be running at full efficiency. That, said Sagebiel, is far more efficient than it would be to heat a couple of dozen buildings, each with its own boiler running at partial efficiency.
According to campus Facilities Mechanical Engineer Candice George, the new cooling system is estimated to save around $334,000 annually in energy and around $11,000 in maintenance. In addition, buildings such as the new Pennington Student Achievement Center, which opened earlier this year, can be constructed without devoting square footage to boiler rooms and air conditioning systems, making way for a few hundred square feet of classroom and office space.