Across Texas, Arizona, Georgia and Virginia, crews are racing to build the data centers that power artificial intelligence. They pour concrete, set steel, pull cable and install electrical and cooling systems on sites where summer temperatures often pass 100°F. Many of these crews work full shifts in the sun or inside unfinished shells with no ventilation, while wearing hard hats, high-visibility vests, flame-resistant clothing and harnesses.
The buildings they put up will keep servers cool. Nothing does the same for the people building them.
Photo Courtesy: Clément Messeri
Clément Messeri wants to change that. He is a materials and nuclear engineer and the cofounder of Clema, and he has built a wearable active-cooling system that works like portable air conditioning for the body. It cools the worker directly, wherever the job takes them.
A Blind Spot in the Buildout
According to the International Labour Organization, over 2.4 billion workers globally are confronted with high levels of heat at work. In the United States, construction is one of the most impacted industries. That strain is increasing as data center, energy, and manufacturing endeavors increase through the Sun Belt, with further compressed schedules and heat impossible to run from.
Standard protections still matter: water, rest, shade, and shifting work to cooler hours. But none of them helps a worker who is 40 feet up on a steel frame or deep inside an electrical room at 2 p.m. in July. You can’t air-condition a construction site, but you can cool the person.
“Two billion workers are exposed to extreme heat right now with almost no protection,” Messeri says. “We started Clema to close that gap by building lightweight, on-body active cooling hardware that actually works in the field.”
What Are On-Body Cooling Wearables?
On-body cooling wearables are portable devices or garments intended to remove heat close to the body. Personally cooling an employee calls for less equipment and setup than cooling a warehouse, a construction site, a transport van, or a factory.
The Technology: ClemaCore
Photo Courtesy: Clément Messeri
Messeri designed Clema’s core technology, the ClemaCore thermoelectric module, from the ground up. The solid-state system uses electricity to pull heat away from the body. It has no ice, water, refrigerant, or moving coolant loops.
That design solves the main problem with the tools workers use today. An ice vest starts melting as soon as it goes on, and within an hour it is just extra weight. Clema’s system keeps cooling for as long as its battery lasts, and workers can swap batteries in the middle of a shift.
The complete unit weighs under three pounds and fits under the protective gear crews already wear. This constraint drove much of the engineering. Messeri had to balance heat transfer, power draw, battery life, weight, durability, and comfort in a device that people will actually keep on for a 10-hour shift.
“A cooling device that works in the lab but comes off after 20 minutes on a job site hasn’t solved anything,” he says. “Everything we build is designed around how crews really work.”
Engineering Around Real Work Conditions
Messeri leads hardware engineering, materials sourcing, and the thermal performance roadmap at Clema. He designed the company’s core thermoelectric module, ClemaCore, from the ground up. The work requires balancing heat transfer, electrical demand, battery duration, weight, durability, and comfort.
For on-body cooling wearables, laboratory performance is only part of the design problem. A device must fit into daily routines, remain usable during long shifts, and avoid interfering with required gear. Clema’s development is oriented toward industrial settings where mobility and protective equipment influence consistent use.
From Berkeley Labs to the Job Site
Photo Courtesy: Clément Messeri
Messeri’s career has followed one idea: how materials and energy systems behave under extreme conditions.
He earned a bachelor’s degree in materials science and engineering, with a minor in nuclear engineering, from the University of California, Berkeley, and went on to complete a master’s degree in materials science and engineering there. At Lawrence Berkeley National Laboratory, he studied high-temperature ceramic composites and how their thermal and mechanical properties hold up in harsh environments.
He then joined Tyfast, where he worked on solid-state cooling and fast-charging battery systems. Those two technologies are the foundation of a wearable active-cooling device. Next, at the energy consultancy Energy and Environmental Economics (E3), he built models of industrial energy demand, including peak-load analysis for U.S. utility clients. That work showed him directly how heat and power demand interact across the American grid.
By the time he cofounded Clema in 2025, he had working expertise in each of the fields the product needed: materials science, thermal engineering, battery systems, and energy modeling.
Leading Clema’s Engineering
At Clema, Messeri leads hardware engineering, materials sourcing, and the thermal performance roadmap. The company’s product exists because he designed its core module and turned it from a concept into field-ready hardware.
Clema is now running field trials of about 100 units, its first large deployment with workers in real conditions. The team is collecting performance data and worker feedback to guide the next version of the product before a wider rollout.
Why It Matters Now
The United States is in one of the largest construction booms in decades, driven by AI data centers, grid upgrades, and new manufacturing. The workforce behind that buildout is also the workforce most exposed to heat. Keeping crews safe and productive through the summer is both a health issue and a scheduling issue for the projects now underway.
“The industry is spending billions to keep chips cool,” Messeri says. “The people building those facilities deserve the same engineering attention.”
On-body cooling is not meant to replace hydration, rest, acclimatization, training or employer heat plans. It adds a layer of protection those measures can’t provide: cooling that moves with the worker. If Messeri’s field trials hold up, wearable cooling could become standard gear on American job sites, alongside the hard hat and the safety vest.
Learn More
Learn more about Clema at clemacooling.com. Professional information about Clément Messeri is available on his LinkedIn profile.
