Luminaire Light Loss Factors (LLFs)
It is important to specify any relevant light loss factors (LLFs) so that your calculations will reflect the true lighting conditions as closely as possible. The Total LLF acts to reduce the amount of light that reaches the surfaces and calculation grids. A Total LLF of 0.77 means that the calculated lighting metrics (illuminance, luminance, etc.) will be reduced by a factor of 0.77 compared to "initial" conditions (no LLFs applied). The condition with LLFs applied is sometimes called the "maintained" lighting condition, and light loss factors are sometimes called maintenance factors.
Some of the LLFs are considered "recoverable," such as Luminaire Dirt Depreciation (LDD), while others are considered "non-recoverable," such as Ballast Factor (BF). Only the factors that are entered into the dialog's fields will contribute to the Total LLF.
The LLFs listed in AGi32's Light Loss Factor specification dialog (Specify button) are all defined by the Illuminating Engineering Society of North America (IES) in the IES Handbook. Additional information on Light Loss Factors may be found in the IES Handbook. (www.ies.org)
