Maintenance is vital to lighting efficiency. Light levels decrease over time because of aging lamps and dirt on fixtures, lamps, and room surfaces. Together, these factors can reduce total illumination by 50% or more, while lights continue drawing full power.

The following basic maintenance suggestions can help keep your lights operating at their optimum energy efficiency:

 

Clean fixtures, lamps, and lenses every 6–24 months by wiping off the dust. However, never clean an incandescent bulb while it is turned on. The water's cooling effect will shatter the hot bulb.

Replace lenses if they appear yellow.

Consider group relamping. Common lamps, especially incandescent and fluorescent lamps, lose 20–30% of their light output over their service life. Many lighting experts recommend replacing all the lamps in a lighting system at once. This saves labor, keeps illumination high, and avoids stressing any ballasts with dying lamps.

Clean or repaint small rooms every year and larger rooms every 2–3 years. Dirt collects on surfaces, which reduces the amount of light they reflect.