Goodlite G-19995 13-watt Compact Fluorescent Plug-In 2-Pin Light Bulb with GX23-2 Base, Cool White;

Replace your incandescent bulbs with CFL bulbs. It's one of the easiest things you can do that will have the biggest energy impact. These CFL's use up to 75% less energy than standard incandescent bulbs and last up to 12 times longer. Incandescent bulbs are very inefficient, 90% of the energy used by incandescent bulbs turns into heat, only 10% of the energy is converted to light.