IES RP-36-03:2003 Edition

All lighting systems experience deterioration of performance during operation that affects illuminances and
the appearance of the lighted space. Lamps and ballasts fail and need to be replaced. The visual appearance of the site may be altered due to lumen depreciation, loss of uniformity, and color shift. And the luminous flux of luminaires may be reduced due to dirt and dust accumulation on and degradation of reflector surfaces and lenses. Most of these phenomena are expressed as recoverable light loss factors, indicating that the light loss can be predicted and controlled using various maintenance methods. By extension, the maintenance method will influence the number of luminaires required in an original design and the component types allowed in an existing design, providing savings opportunitiesfor both initial investments and operating costs.