Replace incandescent lamps with more energy efficient lamps in good fixtures. One can use compact fluorescent lamps in an efficient fixture, or for even more efficiency use a low wattage LPS lamp in a well-shielded fixture. Consider also time clocking any incandescent fixtures, as mentioned below. It has a relatively long life compared to most other lamps, especially compared to incandescent. These lamps are a quartz tube filled with mercury gas under pressure.
Light is produced when an electric current passes through the mercury vapor.
For savings, one can and should use the lowest possible wattage for the application. Many of the existing fixtures have a great deal of associated glare due to lack of adequate light control. With a good fixture, less light is wasted and lower wattages can be used. In a glare-free lighting environment, remarkably low light levels still give excellent visibility. It is in the high glare areas, even with much higher levels of lighting, that we have difficulty seeing well at night.