ET26SWE0001 - Evaporative Cooler for Air-Cooled Chillers

California hosts a significant number of data centers and telecommunication facilities, which are high energy consumers. Data centers in the United States account for over four percent of total annual electric energy consumption, and in California account for approximately two percent of total demand [1, 2]. These facilities will continue to grow due to advancements in artificial intelligence (“AI”) and increasing demands for data services. Significant electric energy is needed to cool equipment, making energy efficiency (“EE”) measures crucial for this industry to conserve energy while meeting growing demands. Data centers often use air-cooled chillers for lower installation costs, simplicity, and ease-of-use to cool these facilities. They are economical over their water-cooled counterparts but at the cost of reduced efficiency in hotter climates. Peak temperatures typically coincide with peak demand during the day, resulting in greater energy consumption and costs, burdening both customers and the grid. Evaporative cooling retrofit technologies offer an accessible solution for facilities to improve energy efficiency but face barriers due to water shortages and unfamiliarity with commercially available products.

This project proposes a feasibility study for an evaporative cooler retrofit technology in large-scale telecommunications facilities such as data centers. At a selected site, it will demonstrate an adiabatic pre-cooling technology that can be retrofitted onto the condenser coils of existing air-cooled chillers to increase cooling capacity and reduce energy consumption. The emerging technology that leverages this type of pre-cooling is offered as a standard kit that cools the incoming ambient temperature to the system using a mist spray. It overcomes the performance and operational issues experienced by its predecessors by offering water treatment, sanitization, recirculation, and condenser protection. Despite added water usage, the technology reduces energy required for cooling the facilities with less demand for water compared to water-cooled chillers. Water treatment and the condenser membrane protect the system itself from scaling and corrosion, extending equipment lifespan as well. 

This technology will be deployed at a telecommunications facility in a hot, dry climate zone with chillers providing at least two hundred tons of cooling.  It will be assessed for its ability to increase the existing system’s cooling capacity and reduce energy consumption in hot ambient conditions where more energy is needed to provide adequate cooling. Best practices with installation and operation, cost-effectiveness, user feedback, and overall system performance impacts will be documented. A modeling study in EnergyPlus will use the emerging technology specifications, collected data, and weather conditions at the host site for calibration and will be projected across all CA climate zones to analyze savings opportunities, performance impacts, and cost-effectiveness for data centers throughout California. A market study will also be performed to assess the current landscape for this technology. It will identify the prevalence and characteristics of air-cooled chillers in California’s data centers. The market study will also address the opportunities and barriers for chiller retrofits to improve data center energy efficiency.   The final report will help designers, decision-makers, and building operators make informed decisions about adopting the technology. If successful, it can support next-phase studies leading to energy-efficiency measures and enable the technology as a viable retrofit at data centers with large cooling demands and pre-existing air-cooled chillers. Increased adoption will relieve stress on the grid during peak demand and alleviate the energy consumption of a rapidly growing industry.   

[1] ASHRAE Journal, Vol. 67, no. 3, March 2025

[2] https://www.energy.ca.gov/sites/default/files/2024-06/CEC-500-2024-061…