Energy saving lamps, also called compact fluorescents lamp (CFL) or low energy bulbs, saves energy by using the same technology as a fluorescent tube to generate equivalent light outputs to a conventional tungsten filament bulb but with a significantly lower power requirement. Due to the technology used they also offer huge increases in life expectancy over conventional lamps. The marked wattage of all energy saving lamps is much lower than the equivalent conventional bulb, therefore costing less per hour.