LEDs

LED lights do not produce heat, and they are a lot more efficient than pretty much every other type of bulb in existence (Sorry Edison). Anyway, LEDs are very common nowadays and are hooked everywhere, you probably have on burning in your room, and this is how they are so efficient why you are saving so much energy by using them. LEDs are hooked up to a resistor, which only allows the minimum amount of energy needed to pass through the bulb at once. This way, only the energy needed is used, unlike normal bulbs, which need a lot more energy to produce nowhere near as much light as LEDs.