When electrical current passes through a material with electrical resistance, electrical energy is converted into heat. This is known as Joule heating. Heating output depends on the applied voltage, current and resistance of the heating element.

Conductive wire, carbon-based materials and other flexible resistive structures can be engineered into selected garment zones. Element geometry, resistance and placement influence heat distribution, flexibility and surface temperature.

Sensors such as NTC thermistors can provide temperature feedback to an electronic controller. Power can then be adjusted using multiple output levels, PWM regulation or closed-loop temperature control to improve temperature stability and provide over-temperature protection.

Heating areas can be distributed across the chest, back, abdomen, legs or other regions. Different zones may use different element sizes and power levels according to the required body coverage and thermal performance.

Battery voltage, capacity, heating resistance, total power and runtime must be considered as one system. Wiring routes, connectors, lining, insulation and battery placement also influence comfort, durability, washability strategy and manufacturability.

Water requires energy to change from liquid to vapor. During evaporation, that energy is absorbed from the surrounding material, air and body environment, creating a cooling effect. Performance therefore depends strongly on airflow, relative humidity and the rate at which water can evaporate.

Phase Change Materials absorb thermal energy while changing phase, typically from solid to liquid. During this transition they can absorb a relatively large amount of heat with only a limited change in temperature. Cooling duration depends on PCM mass, latent heat capacity, transition temperature and the surrounding heat load.

Integrated fans move ambient air through the space between the body and garment. Moving air increases forced convection and can accelerate evaporation of perspiration. Fan position, internal air space, garment sealing and outlet locations determine how effectively air moves across different body areas.

Thermoelectric modules use the Peltier effect to actively transfer heat when direct current is applied. One side absorbs heat while the opposite side releases it. Effective hot-side heat dissipation is essential because the system must reject both the transferred heat and the electrical input energy.

No single cooling technology is optimal for every application. Ambient temperature, humidity, required runtime, power availability, garment weight and user activity all influence which cooling architecture is most appropriate.