Today in Japan, comfortable lifestyle and environment realized by abundant electric power is being questioned by energy consumption reduction policies called “cool biz” in summer, and “warm biz” in winter. One reason of these policies is the bad energy consumption efficiency of current air-conditioning systems that cool or warm indirectly human body. Several researches have been investigating the effect of direct human body cooling and warming. However, most proposed solutions focus on direct head or neck cooling, using ice to cool a water circulating system, such temperature during use cannot be controlled accurately nor adapted to user and environment conditions. Recently, a Japanese research team developed a portable system using Peltier elements that can both cool and warm neck. Though cooling was demonstrated to affect positively both physiological and psychological state in summer heat environment, in cold climate it could be confirmed for only neck warming but not feet and hands. In our objective of developing effective energy saving technology for direct temperature-conditioning of human body, and in order to reduce the discomfort caused by body chillness, we have proposed and developed a Peltier element based wrist-mounted wearable device that directly warms human body. A first experimental study showed how wrist warming rhythm affects hyperthermic sensation. Then, we verified whether the thermal sensation of the body, including the extremities, is improved by changing the position where the wrist is warmed.

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