The old light bulb should be incandescent, and it should be screw type (direct screw). Just buy a screw-type energy-saving lamp The wattage depends on how big you used it before. Generally, the wattage of energy-saving lamps is 1/3- 1/4 of incandescent lamps, which is not necessarily the case. There are many energy-saving lamps now, and the quality lumens vary greatly. 60 watt incandescent lamp.