Norma Frank, CLMC recently contributed a maintenance column to LD+A that talks about LED streetlighting maintenance.

Traditionally, HID luminaires are cleaned when they are relamped, limiting light loss imposed by luminaire dirt depreciation (LDD). As stated above, LED luminaires promise much longer service life. They may present a different failure mode based on output rather than mortality along a curve that in time produces a steady failure rate. As a result, LDD’s significance as a light loss factor may be much greater for LED roadway and area luminaires, potentially reducing useful life.

She points out that what’s been missing is evidence upon which maintenance recommendations can be made, which was addressed in a study conducted by VTTI:

The IES engaged the Virginia Tech Transportation Institute to study and quantify LDD in a range of LED roadway luminaire types. The resulting report, Measure and Report Luminaire Dirt Depreciation (LDD) in LED Luminaires for Street and Roadway Lighting Applications (IES RES-1-16), provides an excellent start to understanding this issue and making maintenance recommendations.

Click here to read the article.