Application of a plastic optical fiber and voice synthesis LSIs realized an easy-to-use room air conditioner, which was remotely controlled by fiber-optic remote control system with a removable IR-transmitter, and informed vocally the way of better and more economical air conditioning. The removable IR- transmitter is used in two ways: IR- transmitter of wireless remote controller and that of fiber-optic remote controller. A combination cord composed of a plastic optical fiber and electric wires was developed and it was confirmed that the combination cord possessed high mechanical strength enough for household appliances. The synthesized messages consist of not only temperature and remaining time of timer but also the state of the air conditioner. Moreover, there are messages to inform of excessive heating and cooling and time of air filter cleaning as advice for energy saving.