International Energy Innovator of the Year Jagan Pillai Explains Air Conditioning’s Biggest Problem

Named the 2026 International Energy Innovator of the Year, engineer Jagan Pillai argues that air conditioning's biggest energy problem isn't heat. It's humidity.

Check the weather app on a sticky summer afternoon, and you'll see two numbers: the actual temperature and what it “feels like.” On a humid day, the second can be far higher than the first.

That gap is humidity at work. Our bodies cool down by sweating, and as sweat evaporates, it carries heat away.

When the air is already full of moisture, sweat evaporates slowly, so we stay hot and sticky. That's why a 90-degree day in a humid city can feel well over 100.

That same moisture is the hidden reason air conditioning uses so much power, says Pillai, a licensed Professional Engineer and the Association of Energy Engineers' 2026 International Energy Innovator of the Year.

“Most people think an air conditioner's job is to make air cold,” Pillai says. “In a humid city, a huge part of its job is making air dry, and the way we do that is surprisingly wasteful.”

Moisture removal accounts for about 30 percent of the total air-conditioning cooling load, according to a 2018 study in Scientific Reports, with a higher proportion in many tropical and subtropical climates.

The key is the dew point. Air can hold only so much water vapor.

Cool it far enough, and the extra moisture turns to liquid; that temperature is the dew point. It's why grass is wet on summer mornings, and why a glass of iced water “sweats.”

“Nearly every conventional air conditioner, from a window unit to the giant chiller plants that cool office towers, dries air the same way: it chills the air below its dew point so the moisture condenses out and drains away,” Pillai says.

That means cooling air far colder than anyone wants, and in many large buildings, reheating it before it reaches the room. A Lawrence Berkeley National Laboratory report explains that, for centrifugal chillers, raising the chilled-water supply temperature by one degree Fahrenheit can improve operational efficiency by roughly 1 to 2 percent.

It gives a specific comparison: supplying water at 55°F rather than 40°F can make a chiller approximately 15 to 30 percent more efficient. The benefit depends on operating conditions and whether the system can still meet its cooling and humidity-control requirements.

And the extra power is needed at the worst possible time. According to the International Energy Agency, cooling makes up only around 10 percent of annual electricity use worldwide but about 30 percent of peak demand.

During heat waves, cooling can reach up to 70 percent of peak electricity demand in areas where at least 70 percent of households have access to cooling.

Overcooling has a visible side effect: office workers in sweaters in July. A 2021 study in Scientific Reports notes that indoor temperatures in US offices have been found to be lower in summer than in winter.

It also cites an earlier 2015 estimate that overcooling US commercial buildings wastes about $10 billion in electricity annually.

“That sweater is a symptom,” Pillai says. “In many buildings, the air is cold because the system had to make it cold to dry it. Comfort was never the goal. Humidity control was, and we paid for it twice.”

Pillai, also named a 2025 ACEEE Champion of Energy Efficiency in Industry, has spent much of his nearly two-decade career pulling those two jobs apart.

“Temperature and humidity are different problems,” he says. “If you can remove moisture another way, you don't have to overcool anything. You cool the air just enough to be comfortable.”

One way is with desiccants, materials that absorb moisture directly from the air, like the silica packets in a new pair of shoes. A desiccant system dries the air first, so the cooling equipment can run warmer and more efficiently.

There is a catch: once a desiccant is full of moisture, it has to be dried out with heat before it can absorb more. Pillai's solution was to use heat that buildings were already throwing away.

The other catch is that desiccant systems often look risky when judged the conventional way, against a single hottest, muggiest “design day.” So during his decade as Practice Leader for Energy and Analytics at the sustainability design firm Atelier Ten, Pillai developed a methodology that looks at how a building performs in every hour of the year, not just the hottest day, and adjusts the dehumidification strategy to what the building actually needs at each moment.

That approach shaped two of New York University's most sustainable buildings. At the Center for Urban Science and Progress at 370 Jay Street in Brooklyn, Pillai's analysis supported a design combining desiccant dehumidification, heat recovery, on-site power generation, and thermal energy storage to cut peak demand.

According to Atelier Ten, the project earned LEED Platinum Core and Shell and LEED Gold Commercial Interiors certification, with nearly 50 percent estimated energy cost savings from the combined strategies.

At the LEED Gold-certified John A. Paulson Center at 181 Mercer Street in Manhattan, the desiccant system is regenerated with waste heat from NYU's campus cogeneration plant.

Atelier Ten reports that this and other strategies, including displacement ventilation, decoupled systems, and enthalpy recovery, contributed to a 46 percent reduction in energy costs.

Heat waves are becoming more humid, which drives up the need for air conditioning, and power grids are feeling it.

“Efficiency used to be about the utility bill,” Pillai says. “Now it's about whether the grid can keep up on the worst afternoon of the summer. Every kilowatt we don't need at that moment matters.”

Newer materials could make the idea easier to scale. Metal-organic frameworks, or MOFs, are porous crystalline materials that can capture water vapor.

In a 2018 experimental system, researchers coated heat exchangers with selected MOFs to remove moisture without cooling the air below its dew point, using residual condenser heat to regenerate the materials. The study demonstrates a possible route to more efficient cooling and drying, with potential for larger-scale applications.

Further development and testing would be needed to establish performance across real buildings.

But the test, Pillai says, is always the same: “The question is never whether a technology works in a lab. It's whether it holds up across every condition a real building will see over an entire year.”

The same physics applies at home. An oversized air conditioner cools a room quickly, then shuts off before it removes much moisture, leaving the space cold but clammy.

People turn the thermostat down further, using more energy without feeling better.

“Comfort isn't just a number on the thermostat,” he says. “Get the humidity right, and you can run warmer, use less energy, and actually feel better.”

As cooling demand grows, Pillai’s approach puts humidity at the center of the efficiency conversation. Separating moisture removal from temperature control offers a way to reduce unnecessary cooling while keeping people comfortable.

The goal is practical: buildings that use less energy and work better for the people inside them.