Air conditioners have been recently highly developed, so refrigeration capacities are sufficient for

living rooms and oftices. Furthermore. mechanical elements such as compressors, heat exchangers,

electric fan motors and refrigeration cycles have also been improved, and energy efficiencies of air

conditioners are higher and higher in these days. However, we are not satisfied somehow by air

conditioners. We do not feel so well as we feel in natural breeze in country sides where are located near

mountainsa nd rivers. Why don't we feel comfortable? What is short in air conditioners? Air from an

air conditioner usually flows at a constant speed. It does not change all the time except we made

change in our own way. On the other hand, natural wind fluctuates all the time in all directions. We

can not appreciate air velocity itself but the changeo f air velocity. We sometimesn otice that we are

not sensible atler we exposed at constant cool wind for a long time. We may feel comfortable when we

recognize cool wind without consciousness.

• wind