The future of air conditioning could already be in use in a SoCal train station

The future of air conditioning could be in a train station in Anaheim.

The 3 million people who pass through Orange County’s ARTIC station annually are experiencing climate control by radiant cooling — a technology experts say could eventually replace the forced-air AC we’re used to.

AC has become one of the world’s most used defenses against extreme heat, but it’s simultaneously making that heat worse.

Traditional AC systems consume vast amounts of electricity and often rely on greenhouse gases, helping fuel a vicious cycle: More warming drives more AC, which drives more warming.

Radiant cooling offers a greener, more efficient approach that experts say is gaining popularity in homes across California.

How radiant cooling works

A traditional air conditioning system works by circulating a refrigerant that rapidly changes between liquid and gas states, absorbing heat from indoor air and releasing it outside. These forced-air systems push cooled air through ducts in a building — resulting in that familiar blast of cool, dry wind from a vent in the ceiling. The process runs on electricity, and common refrigerants can be powerful greenhouse gases if they leak.

Heat pumps use a similar refrigerant cycle but can reverse direction, moving heat out of a building in summer and into it in winter.

In a radiant cooling system, however, air-to-water heat pumps transfer energy into a centralized water loop, often using less refrigerant. Radiant cooling systems circulate their chilled water through coils embedded behind panels that can be in floors, walls or ceilings. The water in these radiant systems is typically cooled to about 60 degrees Fahrenheit, while the chilled panels remain between 68 and 75 degrees.

A person standing nearby then radiates body heat toward the cooler panels, which act as a sponge for thermal energy. This creates a sensation of coolness even if the surrounding air remains warm.

“The idea is that basically you take advantage of thermal radiation to exchange heat between people and surfaces,” said Aaswath Raman, an engineering professor at UCLA.

Saul De Los Santos, a sales associate at Messana Hydronic Technologies, compared radiant cooling to the feeling of walking into a parking structure.

“As soon as you walk into that parking garage, even on a hot day, you start feeling much cooler,” De Los Santos said. “And that’s because those cold walls are extracting heat from your body, leaving you cooler.”

Water can carry 3,400 times more heat energy than air, making radiant cooling significantly more energy-efficient compared to traditional AC systems.

“You need a much smaller volume of water to distribute the same amount of energy through a space,” said Carlos Duarte, an assistant researcher at UC Berkeley’s Center for the Built Environment.

The ARTIC train station in Anaheim is one of just a few places in Southern California using radiant cooling today.

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Sena Chang

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LAist

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How it feels

Only a handful of radiant cooling systems exist across Southern California, mostly in commercial and office spaces.

One is the United States Courthouse in downtown L.A.

Another is Anaheim’s relatively new train station. I went there to feel what it was like on Tuesday.

It was sunny and a hot 84 degrees outside. But inside the ARTIC station, the heat seemed to loosen its grip over my body at once, leaving me feeling deeply comfortable. It was subtle and all-consuming at the same time. Because unlike traditional AC, there was no sudden chill on my skin.

I walked to a nearby hotel to compare radiant cooling to traditional AC. I immediately felt cool air blowing over me, and there was an artificiality about the chill of the lobby that left me a little too cold.

The future of radiant cooling

Preliminary research suggests people experience higher levels of comfort with radiant cooling compared to conventional AC.

But Duarte said the U.S. lacks the infrastructure to implement radiant systems on a residential level.

“I think one of the biggest challenges is that many installers or contractors are not familiar with radiant systems, and there needs to be a lot of coordination among the trades,” he said.

A huge barrier for homeowners is cost. Purchasing and installing a radiant system on a home can cost around $20 per square foot. By comparison, a ducted HVAC installation costs $5 to $10 per square foot, while a mini-split system averages $3 to $10 per square foot.

For now, residential radiant systems remain a “relatively niche concept,” according to Raman.

But experts say radiant cooling is becoming more widespread across the state, and researchers are eyeing the 2028 Olympics as an opportunity to deploy these systems on a larger scale.

“We’ve certainly seen an increase in sales specifically for California, but also across the U.S.,” said De Los Santos, who works on residential applications of radiant cooling.

Beyond the home, radiant cooling is highly applicable in open-air spaces like the ARTIC station, where cooling vast quantities of air can be impractical.

In 2025, Raman and a team of researchers designed an outdoor radiant cooling system on the UCLA campus and at the San Fernando Swap Meet that made an area feel up to 10 degrees cooler.

“One thing we’re hoping is that as part of the Olympics, we can also have this as something that’s available for visitors,” Raman said.

“That will also showcase to the world the potential of this technology.”