Energy-saving light bulbs. Two different types of compact fluorescent lamps (CFL) or energy-saving light bulbs including a spiral type (left) and a rounded type (right). The spiral type is 11 watts and is equivalent to a 60 watt incandesent bulb. The rounded type is 15 watts and is equivalent to a 75 watt incandescent bulb. Fluorescent bulbs produce less heat than filament bulbs, therefore more of the electrical energy is converted to light, making them more efficient.