How can you use less energy if you don´t know how much energy you are using?

By the time you get your electrical bill at the end of each month, it’s too late. What if you knew from the moment you plugged in your cell phone charger or turned on your AC how much energy you’re using right then, at that very moment? That’s the idea that inspired the Power Aware Cord, which tells you how much energy an appliance is consuming through a visual system of blinking or streaming lights that speed up or slow down depending on the amount of energy being used.