What is active thermal regulation apparel?
The Direct Answer
Active thermal regulation apparel is clothing that uses an electrical power source to heat or cool the wearer directly — holding the body's own temperature steady as the air around it changes through the day.
Active thermal regulation is a category distinct from two adjacent categories it is often confused with.
The first is passive insulation, meaning a fleece, a puffer, or a wool sweater. Insulation slows the loss of body heat by reducing convective and conductive transfer to the environment. It can hold your temperature only as long as your body produces more heat than the insulation lets escape. It cannot add heat once you have already lost it, and it cannot cool you under any circumstances.
The second is air conditioning, along with its mobile cousins, portable AC units and personal fans. These condition a volume of space around the person. They cool rooms. They cool cars. They cool stadiums. What they do not do is condition the person. Their effect ends the moment you leave the cooled volume.
Active thermal regulation does what neither can. It conditions the person directly, heating or cooling the body itself through apparel the wearer already has on. That micro-climate moves with the wearer. The cold morning commute, the over-cooled office, the hot afternoon drive home, the cold evening sideline, and the hot summer concert all belong to the same person with the same need to regulate temperature. Each one asks something different of what they are wearing.
Why "Active" Matters
The word "active" in active thermal regulation is the distinction that defines the category. A wool sweater is passive. It can only manage heat your body has already made. A heated hoodie like EarthBae Core is active. It adds heat your body did not produce. A cotton t-shirt is passive. It leaves the cooling entirely to your own sweat. A fan convection cooling vest like EarthBae Air is active. It speeds the rate at which heat leaves your body, far beyond what fabric alone can do.
EarthBae built four products around this category, two for heating and two for cooling, so the same person can use the same 7.4V battery to regulate temperature in whatever direction the day demands.
How does EarthBae active heating work?
The Direct Answer
EarthBae active heating works by passing low-voltage electrical current through engineered composite heating elements built into three zones of the garment. One zone sits on each side of the chest and one runs across the back.
The elements are sealed inside the garment, with no visible wires and no exposed hardware. Power comes over a standard USB-A connection, tuned to perform best on the EarthBae 7.4V battery. Remove the battery before cleaning and follow the care label sewn into your garment.
What even heat means for a garment you wear all day
An even temperature field is more than an engineering preference. It changes three things the wearer experiences directly.
First, the garment performs at its temperature setting across the whole zone. There are no patches that feel notably warmer or cooler than the rest. Set it to low and the zone is low, edge to edge.
Second, warm-up is fast. The zones reach working temperature within minutes, so the heat is there for the cold start instead of arriving ten minutes into the commute.
Third, the system runs efficiently. An element that heats evenly never overshoots in one spot to compensate for a weak spot elsewhere. That efficiency is part of how EarthBae Core and Heat hold 8 to 10 hours of regulation on the low setting from one 7.4V battery.
One on each side of the chest and one across the back, warmed together at the setting you choose.
The everyday setting. A full workday of stable thermal regulation on one charge.
Press the button and the zones reach temperature before you're out the door.
Three settings, one control. No app, no menu, nothing to manage.
An even temperature field is more than an engineering preference. It changes three things the wearer experiences directly.
First, the garment performs at its temperature setting across the whole zone. There are no patches that feel notably warmer or cooler than the rest. Set it to low and the zone is low, edge to edge.
Second, warm-up is fast. The zones reach working temperature within minutes, so the heat is there for the cold start instead of arriving ten minutes into the commute.
Third, the system runs efficiently. An element that heats evenly never overshoots in one spot to compensate for a weak spot elsewhere. That efficiency is part of how EarthBae Core and Heat hold 8 to 10 hours of regulation on the low setting from one 7.4V battery.
Why 7.4V — and Why One Battery for Everything
Voltage is the design decision underneath every heated garment. It shapes heat output, battery size, runtime, and how the whole system is built.
EarthBae chose 7.4V and then built every product around it, so a single battery serves the entire line across the year.
7.4V delivers enough output for genuine thermal regulation in cold conditions while keeping the battery small and light enough to carry all day without noticing it. That balance is what makes an eight to ten hour runtime on low realistic in a garment you actually wear.
The EarthBae battery is rated 55.44 Wh, printed on the pack as 14400mAh at 3.85V nominal. It carries a 7.4V DC output for the garments and standard USB rails alongside it, which is why Core, Heat, and Air run on ordinary USB-A power and perform best on the EarthBae battery.
Building all four products, Core, Heat, Air, and Chill, on one standard means a battery bought with any EarthBae product powers every other EarthBae product. One connector, one charging protocol, one spare in the bag regardless of the season.
It also means the battery outlives any single garment. When it reaches end of life, EcoDispose takes it back free, along with any other 7.4V battery from any brand.
How does fan convection cooling work?
The Direct Answer
Fan convection cooling combines two thermodynamic mechanisms. Embedded fans force air movement across the wearer's skin and clothing, increasing convective heat transfer to the surrounding air. Simultaneously, accelerated airflow accelerates the evaporation of sweat — a latent heat absorption process that removes substantial heat from the body. Both mechanisms work in parallel.
The physics is split between sensible heat transfer and latent heat absorption. Both are real. Both contribute to the cooling effect. Understanding the difference helps explain when fan convection cooling works best — and when it does not.
Mechanism one: forced convection
Convection is heat transfer between a solid (the body) and a moving fluid (the air around it). The rate of convective heat transfer depends on the temperature difference between the body and the air, the exposed surface area, and — critically — the velocity of air movement across the surface. A still day at 75°F feels warmer than the same temperature with a 10 mph wind for exactly this reason: faster-moving air carries heat away from the body more efficiently.
A fan convection vest replicates the wind effect locally and reliably. The embedded fans positioned at the lower-side waist circulate air upward across the back and shouldersat a controlled velocity, increasing convective heat loss continuously regardless of ambient wind conditions.
'Two thermodynamic mechanisms working in parallel'
Mechanism two: enhanced evaporation
Sweat evaporation is the body's primary mechanism for shedding heat in hot conditions. The evaporation of one gram of water from the skin absorbs approximately 2,400 joules of energy — energy that comes from the body. This is why sweating cools you. The water phase change carries heat away.
But evaporation only happens when sweat can actually move from a liquid state on the skin into water vapor in the surrounding air. In still, humid environments, the air near the skin saturates quickly. Sweat builds up. Evaporation slows. The cooling effect stalls.
Forced airflow from a fan does two things to fix this. It moves saturated air away from the skin and replaces it with drier air, sustaining the evaporation rate. And it accelerates the phase change itself — sweat evaporates more quickly from a surface with high airflow than from a still one.
The humidity dependency
Fan convection cooling is highly effective in dry and moderate-humidity environments. As ambient humidity rises, evaporation becomes constrained — the air near the body cannot accept additional water vapor as readily, and the latent-heat mechanism weakens. The convective component continues to work, but its contribution alone is smaller than the combined effect.
This is the design boundary of fan convection cooling — and the reason EarthBae also makes a liquid conduction vest for environments where evaporation cannot do enough work.
EarthBae Air is built for this mode
EarthBae Air is a fan convection cooling vest, built for variable, dry-to-moderate-humidity conditions where the wearer is in motion. Two fans set low at the sides drive convective and evaporative cooling upward through the vest. The fit is athletic, the aesthetic is Sportif, and the battery is the same 7.4V standard that powers the heating products.
Source · HEAT-SHIELD Project · 2022 Ciuha, U., Pogačar, T., Bogataj, L. K., et al. Efficacy of cooling vests based on different heat-extraction concepts: The HEAT-SHIELD project.
Building and Environment, 2022. The study evaluated 23 commercially available cooling vests across four cooling-concept categories — conduction, convection, evaporation, and hybrid. Findings confirmed that fan-driven evaporative-convective vests perform well in dry-to-moderate-humidity environments but that conduction-based vests (liquid or PCM) outperform in high-humidity environments where evaporation is constrained.
Physics: Forced Convection
Convection is heat transfer through fluid movement — in this case, air. Forced convection uses mechanical means (fans) to accelerate the rate of heat transfer beyond what natural convection achieves. Newton's Law of Cooling states that the rate of heat loss is proportional to the temperature differential and the convection coefficient — fans dramatically increase the convection coefficient.
Why Fan Placement Matters
EarthBae Air positions its fans low on the sides, at the waist — the intake point for an upward airflow channel. Drawing air in at the lower torso and pushing it up and out through the vest flushes the hot, humid air that collects against the skin and replaces it with cooler, drier air across the whole core and back. Low-side placement also keeps the fan units clear of the arms and shoulders, so the airflow path stays unobstructed through a full range of motion. Fans mounted high on the chest or shoulders would short-circuit that channel — moving air across a small area instead of flushing the entire torso.
Best Use Conditions
Active use — walking, physical work, athletic movement. Moderate humidity. Variable heat environments. Commuting. Outdoor sports. Any situation where the body is generating its own heat through activity.
Limitations
Effectiveness reduces as humidity rises, because the evaporative gradient compresses and convection has less moisture to accelerate. Also less effective in purely static high-heat environments where conduction provides more consistent suppression.
EarthBae Air Product
Two visible side fans. Unbranded design. Same 7.4V battery as EarthBae Core, Heat, and Chill.
How does liquid conduction cooling work?
The Direct Answer
Liquid conduction cooling works by circulating chilled water through tubing held in contact with the body. Heat transfers from the body into the water by direct conduction and is carried away. Because the mechanism does not rely on evaporation, it works in humid conditions where fan-driven cooling is constrained.
Conduction is heat transfer through direct contact between two materials at different temperatures. The rate depends on contact area, the thermal conductivity of both materials, and the temperature difference between them. In a liquid conduction vest, the body is one material and the chilled water is the other, with thin polymer tubing holding them in thermal proximity.
Why conduction works in humid air
Evaporative cooling, whether from sweat alone or accelerated by a fan, depends on water changing phase from liquid to vapor. In humid conditions the surrounding air is already close to saturation. There is nowhere for additional vapor to go, evaporation slows, and cooling slows with it.
Conduction is indifferent to humidity. The transfer is direct, body to water, through contact. A humid afternoon and a dry one produce the same conduction performance, because the mechanism does not depend on the air's capacity to absorb moisture.
That makes conduction the right mechanism for sustained heat in still air, and for heat you are sitting in rather than moving through.
EarthBae Chill is built for this mode
EarthBae Chill is a liquid conduction cooling vest for sustained heat, including humid heat where evaporation cannot do enough work.
You fill the reservoir with water and an ice pack. A battery-powered pump circulates the chilled water through tubing across the garment, drawing heat off the core by direct contact. It runs 7 hours per charge on the EarthBae 7.4V battery, one hour less than the heating products, and it ships with a battery.
Between uses, refill and refreeze. The cooling lasts as long as the water stays cold and the pump keeps running.
Why conduction wins in humid environments
Evaporative cooling — sweat, fan-driven or otherwise — depends on the ability of water to phase-change from liquid to vapor. In humid conditions, the surrounding air is already near saturation. There is nowhere for additional water vapor to go. Evaporation slows. Body cooling slows with it.
Conduction does not care about humidity. The heat transfer is direct, body to liquid, through physical contact. An 80% relative humidity day and a 30% relative humidity day produce the same conduction cooling performance — because the mechanism is independent of the air's capacity to absorb water vapor.
This makes liquid conduction the appropriate choice for three categories of use: industrial work in hot environments (foundry, welding, manufacturing, utility line work), any setting under protective clothing (where evaporation from the skin is restricted by the over-garment), and sustained static heat exposure (long shifts where the wearer is not moving enough for ambient airflow to do much work).
Ergonomics · 2021 Ciuha, U., Tobita, K., McDonnell, A. C., & Mekjavic, I. B.Cooling efficiency of vests with different cooling concepts over 8-hour trials.Ergonomics, 64(5), 625–639.Findings: liquid cooling vests (LCVs) and fixed-source air cooling vests provide "unhindered and continuous cooling" over extended duration, while passive cooling vests (PCMs, phase-change materials) and evaporative cooling vests have "limited operational duration." For high-humidity environments and under protective clothing, the study confirms that conduction-based cooling outperforms evaporative cooling.
EarthBae Chill is built for this mode
EarthBae Chill is a liquid conduction cooling vest — designed for sustained, high-heat, high-humidity environments where evaporative cooling cannot do enough work. The vest circulates cooled liquid through tubing in direct contact with the wearer's torso, drawing heat from the core through direct thermal conduction. The battery is the same 7.4V standard as Air, Heat, and Core — interchangeable across the EarthBae ecosystem.
In high humidity environments, the evaporation gradient is compressed — convection cooling becomes less effective, and liquid conduction (EarthBae Chill) becomes the mechanistically superior choice.
Physics: Conduction
Conduction is heat transfer through direct contact between two materials at different temperatures. The rate depends on contact area, the thermal conductivity of both materials, and the temperature difference between them. EarthBae Chill circulates cooled liquid through tubing held against the skin, so heat moves straight from the body into the liquid and is carried away — no airflow, no evaporation required.
Why Contact Placement Matters
Conduction only works where the tubing meets the body, so coverage and steady contact decide performance. Sparse or loose contact leaves heat in the core. Consistent contact across the torso is what makes conduction efficient.
Best Use Conditions
Sustained heat where you are holding position rather than moving. Humid conditions where evaporation is constrained. Long outdoor events, still air, and afternoons that do not let up.
Limitations
Conduction cools where the loop contacts the body, so it concentrates on the core rather than the full skin surface. It carries more hardware than a fan vest, needs refilling and refreezing between uses, and favors sustained heat over fast, dynamic activity, where fan convection is the lighter choice.
EarthBae Chill Product
Pump-circulated chilled water. Humidity-independent. Unbranded design. 7 hours per charge on the EarthBae 7.4V battery, shipped with a battery.
Air vs Chill — choosing the right cooling mode
Both EarthBae Air and EarthBae Chill are active cooling mechanisms. The difference is the physics they leverage — and the conditions in which each mechanism excels.
For Movement. For Variable Heat.
- Dry-to-moderate humidity
- In motion — commuting, athletic, urban
- Convection + evaporation (parallel)
- Performance reduces as humidity rises
- Restricted under clothing
- 7.4V unified standard battery
- No refilling between uses
For Stillness. For Extreme Heat.
- Hot and humid; sustained heat
- Sustained heat, holding position
- Direct thermal conduction
- Humidity-independent
- Works effectively under clothing
- 7.4V unified standard battery
- Unaffected by humidity
The Complete EarthBae Active Thermal Regulation Ecosystem
Four products. Three mechanisms. One battery standard. EarthBae is one of the first brands in Active Thermal Regulation to put active heating and active cooling on a unified 7.4V ecosystem, with free battery recycling at end of life.
Heated Hoodie
Heated chest and back inside a heavyweight hoodie, with the hood, sleeves, and fabric weight covering the rest of you. Built for low to moderate mobility. Runs 8 to 10 hours on low.
Heated Vest
Heated chest and back with your arms fully free. It runs the same heating system as Core in a slim, athletic shape built for movement and layering. Runs 8 to 10 hours on low.
Fan Convection Cooling Vest
Fan-driven convection. Accelerates evaporative cooling. Best for active use, variable heat. Humidity-sensitive.
Liquid Conduction Cooling Vest
Pump-circulated chilled water. Humidity-independent. Built for sustained heat in still air. 7 hours per charge.
One battery. Four products. Every temperature. EcoDispose recycling at end of life.
Common questions about thermal regulation apparel.
What is active thermal regulation apparel?
Active thermal regulation apparel is clothing that uses an electrical power source to heat or cool the wearer directly— maintaining a stable body micro-climate as ambient temperatures change. This is different from passive insulation (which only resists heat loss) and different from air conditioning (which conditions a room, not a person). EarthBae uses the term to describe a unified product category that includes both heated apparel and active cooling vests on a single battery standard.
How does EarthBae heated apparel work?
EarthBae Core and Heat pass low-voltage current through engineered composite heating elements built into three zones. One zone sits on each side of the chest and one runs across the back. Each element warms evenly across its surface, producing a consistent temperature field across the heated zone. A single button cycles three settings, and low holds a stable baseline for 8 to 10 hours on the EarthBae 7.4V battery.
What does even heat mean in heated apparel?
Even heat means the heated zone holds one consistent temperature across its full surface, with no spots noticeably warmer or cooler than the rest. EarthBae engineers its composite heating elements to this standard. The garment performs at the setting you choose, edge to edge, for the full runtime of the charge.
How does fan convection cooling work?
Fan convection cooling combines two thermodynamic mechanisms. Embedded fans force air movement across the wearer's skin and clothing, increasing convective heat transfer to the surrounding air. Accelerated airflow also accelerates the evaporation of sweat — a latent heat absorption process that removes substantial heat from the body. Both mechanisms work in parallel. Peer-reviewed cooling vest studies (HEAT-SHIELD project, 2022) confirm that fan-driven evaporative-convective vests are effective in dry-to-moderate-humidity environments, with performance reducing as ambient humidity rises.
How does liquid conduction cooling work?
Liquid conduction cooling circulates chilled water through tubing held in contact with the body, so heat transfers directly from the body into the water and is carried away.
EarthBae Chill uses a reservoir filled with water and an ice pack, and a battery-powered pump moves the chilled water through the garment. Because the mechanism does not rely on evaporation, it performs in hot and humid conditions where evaporative or convective cooling is constrained (Ciuha et al., 2021, Ergonomics).
When should I choose fan convection cooling vs liquid conduction cooling?
Fan convection (EarthBae Air) is appropriate for variable, dry-to-moderate-humidity environments where the wearer is in motion — commuting, outdoor activity, urban summer settings. The fan-driven evaporation maximizes cooling efficiency where sweat can evaporate.
Liquid conduction (EarthBae Chill) suits sustained heat, humid conditions, and still air where evaporation cannot do enough work. Long outdoor events, hot afternoons with no breeze, and any stretch of heat you are sitting in rather than moving through.
Why does EarthBae use a 7.4V battery across all products?
The decision serves two purposes. The first is cross-product compatibility: the same battery powers all four EarthBae products, Core, Heat, Air, and Chill. The second is interoperability with EcoDispose, which accepts 7.4V batteries from any heated or cooling apparel brand.
The EarthBae battery is rated 55.44 Wh. A typical 7.4V lithium pack is rated for approximately 300 to 500 charge cycles before meaningful capacity loss, roughly two to four years of regular use.
Is heated apparel safe to wear?
EarthBae heating elements are sealed inside the garment, with no exposed hardware and no direct contact with skin. The system runs at low voltage on a 7.4V battery, and a single button controls three settings. Remove the battery before cleaning and follow the care label sewn into your garment.
The science is real. The products are built on it.
EarthBae Core and Heat apply engineered composite heating to cold environments.
EarthBae Air and Chill apply convection and conduction to heat.
EcoDispose closes the loop at end of battery life.
One Ecosystem. Every climate.
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