Caltech Replaces Water Cooling Towers for Efficiency, Sustainability, and Noise Reduction

Chilled water is crucial to the Caltech campus. It keeps research equipment from overheating and allows HVAC systems to cool classrooms during summer heatwaves. And now, thanks to the $22 million modernization of the Central Utility Plant’s four-decade-old cooling towers, those tasks can be accomplished more sustainably and efficiently, and with less neighborhood noise.

The renovation replaced the plant’s four original cooling towers on Wilson Avenue south of California Boulevard with six 36-foot-tall stainless-steel cooling towers enclosed in a gray and terra-cotta double-insulated metal façade. This allows for recirculated chilled water to be delivered to buildings across campus, including Caltech’s first LEED platinum-certified laboratory, the Linde Laboratory for Global Environmental Science; the Tianqiao and Chrissy Chen Neuroscience Research Building, which opened in 2021; and the Resnick Sustainability Center, now under construction and slated to open in 2024.

“This has been an extremely important project for Caltech’s future, to support research and education while modernizing the campus and making it more resilient,” says John Onderdonk, Caltech’s assistant vice president for facilities operations and services.

The new cooling towers are more efficient and easier to maintain, and will minimize operational outages for the campus community.

To chill the water, high-efficiency pumps push warm water up the tower, where it is sprayed out. Meanwhile, fans pull up air that chills the falling water. Older towers looked like waterfalls on the inside; modern ones are modular, so technicians can inspect components, repair them, and even take them out of service while the rest of the tower can continue to provide cooling.

The new towers slash energy use: they are about 25 percent more efficient and can operate at different levels in different weather conditions thanks to variable frequency drives. They also save water, using the same supply for about 50 percent more cycles than a typical plant can.

“The towers are significantly more efficient in regards to both electricity and water, contributing overall to our campus’s sustainability efforts,” Onderdonk says. “If we reduce our energy consumption, we also reduce our water consumption.”

The replacement of the original cooling towers, which dated to 1980, brought the facility up to current seismic standards and addressed structural issues. In addition, the project expands Caltech’s capacity to provide chilled water to its campus now and well into the future, as the Institute supports new buildings and more energy-intensive research in biology, chemistry, and computational sciences.

The enhanced water-chilling system has already had an impact on campus, notes Brad Nielsen, project manager associate in the facilities operations and services department. During last summer’s two-week heatwave, the new system consistently provided cooling to the campus, even while not yet operating at full capacity.

“On hot days, it’s particularly difficult to chill and recycle water through the campus,” Nielsen says, noting that the warmer outside air will continually heat up the water the system is working to cool. “The old towers would have to run full bore, with colder nightly temperatures relieving the system. But heatwaves were a struggle. The new towers and additional capacity will make it significantly easier for our system to operate in hotter weather.”

“As we observe climate change and the impact of having hotter days in Pasadena, cooling is among the most critical utilities that we provide,” Onderdonk adds. “We’re cooling the campus all day, every day because of the heat generated by bodies, computers, and research equipment. Fully modernizing this system is crucial as annual temperatures rise.”

Additionally, the new towers generate much less noise than before, which is great news for the surrounding community and all those who live, work, and play near the Central Utility Plant.