A fluorescent bulb, on the other hand, contains a gas that produces invisible ultraviolet light (UV) when the gas is excited by electricity. The UV light hits the white coating inside the fluorescent bulb and the coating changes it into light you can see. Because fluorescent bulbs don’t use heat to create light, they are far more energy-efficient than regular incandescent bulbs
At the forefront of the most efficient incandescent alternative are LED and Fluorescent technologies. Both have advantages & technical challenge and provide significantly improved efficacy (lumens/watt) over incandescent lighting. Additionally both technologies open themselves for opportunities to add intelligence beyond just simply providing an incandescent light bulb replacement.