Setting the Photometry Standard for LED Fixtures

LM-79-08 Photometry
All of Sternberg Lighting’s UNRIVALED™ luminaires are tested in accordance with the approved industry measurement standard, IESNA LM-79-08, the Approved Method for the Electrical and Photometric Measurements of Solid-State Lighting Products. This standard specifies procedures for measuring total luminous flux, electrical power, luminous efficacy, and chromaticity of SSL luminaires and replacement lamp products.

It’s important to note that, all UNRIVALED™ luminaires have their LM-79 data generated by testing the LED Arc and Round options within each designed fixture. This may or may not hold true for other lighting manufacturers as they promote their retrofit options. Retrofit kits should be tested within the intended fixture to be LM-79-08 compliant and represent the true delivered lumens from a luminaire. All tests strictly adhere to absolute photometric principles for LEDs and are performed by independent 3rd party test labs.

The Truth Surrounding LEDs and Absolute Photometry
Traditionally, photometric evaluation of lighting products is based on separate tests for lamps and luminaires termed Relative Photometry. Testing is done around lamp source, ballasts and/or transformer. Traditional light sources do not change light output depending on temperature. Therefore, relative photometry does not measures the heat characteristics in regard to efficacy, chromaticity, electrical power...all very important in evaluating LED environments.

Conversely, Absolute Photometry tests the actual light distribution and intensity of the complete LED System as it is packaged for its intended use.

IES LM-80-2008, "Measuring Lumen Maintenance of LED Light Sources" ("LM-80") is the industry standard that defines the method for testing LED lamps to determine their lumen depreciation characteristics. The goal of LM-80 is to allow a reliable comparison of test results among laboratories by establishing uniform test methods. Our LED component partner, Cree, uses the methods defined in LM-80 to test the long-term lumen maintenance of LED lamps.

BUG Ratings TM-15-07
Every UNRIVALED™ luminaire has the new IES TM-15-07 Bug data readily available. The IES Bug ratings system is rapidly becoming the new standard when evaluating light emittance for all luminaires. The new bug (Backlight, Uplight, Glare) rating methodology represents a comprehensive system that limits lamp lumens to values appropriate for the lighting zone.

To determine the BUG rating, the flux distribution by solid angle reporting per IES TM-15-07 measurement procedures are compared to published BUG ratings criteria provided in the specification bulletin. The sphere surrounding a luminaire is divided into zones:

Backlight, which creates light trespass onto adjacent sites. The B rating takes into account the amount of light in the BL, BM, BH and BVH zones, which are direction of the luminaire OPPOSITE from the area intended to be lighted.

Uplight, which causes artificial sky glow. The U rating takes into account the amount of light into the upper hemisphere with greater concern for the lower uplight angles in UL. Lower uplight (zone UL) causes the most sky glow and negatively affects professional and academic astronomy. Upper uplight (UH) is mostly energy waste.

Glare, which can be annoying or visually disabling. The G rating takes into account the amount of frontlight in the FH and FVH zones as well as BH and BVH zones.


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