Light bulbs are among the most energy hungry things people use. They don’t use a lot of electricity on their own. However, when you have half a dozen lights on all day and night, things start adding up. According to Energy Star, compact fluorescent light bulbs (CFL bulbs) use up to 75 percent less energy. That means every four days a CFL bulb stays on it uses as much energy as a regular light bulb does for one.