Light sources that use the least amount of electricity and that can also be used for a longer period of time are considered energy-saving lights. Compact fluorescent lights, or CFLs, are examples of energy-saving lights. Compared to incandescent bulbs, CFLs are four times more efficient, last up to 10 times longer and use 50% to 80% less energy. A CFL bulb is more expensive to purchase compared to an incandescent bulb, but you save money in the long run because of the significant cut in power costs and the long lifespan of the bulb.