Metal Halide Lumen Maintenance
Over time, the gradual reduction in the quality of light emitted from any High Intensity Discharge lighting system occurs for a number of reasons. Called Light Loss Factors (or LLF), these include lamp lumen depreciation, luminaire dirt depreciation, deterioration of luminaire surfaces, dirt on room surfaces, performance of auxiliary equipment and supply voltage. Ambient temperature generally has no effect on the light output of HPS lamps.
Lumen maintenance curves reflect the average lumen maintenance for all lamp types in a given category when operated at rated wattage. Mean lumens for HID lamps are the average light output throughout the rated life of a lamp. For Metal Halide lamps, mean light output occurs at 40% of Rated Average Life. Information on specific lamp types can be obtained from manufacturers’ literature. [read more]