Understanding Family Correlated Photometric Data For Finelite LED Luminaires

Understanding Family Correlated Photometric Data For Finelite LED Luminaires

By Aaron Smith, Product Development Engineer, Finelite

The US Department of Energy (DOE) acknowledges that as the LED market has matured, lighting manufacturers have developed methods to accurately calculate product performance within a product family. Creating a calculated set of results helps manufactures and customers by reducing testing costs without sacrificing the quality of the products or the ability to accurately calculate lighting performance.

This paper describes Finelite’s approach to creating a family of LED luminaires. It will discuss what a family is, identify what performance characteristics scale well and which do not, provide examples of how family calculations are applied, and outline the reports made from these family calculations.

Family correlation is currently being supported by groups such as The U.S. Department of Energy and the Design Lights Consortium® (a project of the Northeast Energy Efficiency Partnerships).


What is a family of products?

Finelite’s fixture families are groups of luminaires where the critical metrics, including photometric, thermal, life, and electrical performance, can be accurately scaled using a combination of LM-79 tests at the luminaire level and well documented specifications at the component level.


The following luminaire characteristics scale well.

Lumen differences due to LED color temperature
LEDs are available in different color temperatures. The color temperature of the LED affects its lumen output; these lumen differences scale well, and are easily calculated.


Lumen differences due to LED technology improvements
LED manufacturers regularly update chip performance. Improvements to the lumen performance of a chip that do not affect thermal performance and life will allow for predictable scaling of the lumen output of the luminaire.


Equal driver performance specification.

  • Equal performance should be expected.

  • Power supplies may be specified from different manufacturers for any number of application reasons or because new improved drivers enter the market and offer overall enhanced performance. Changing a driver used in a luminaire will not impact the performance of the luminaire when operated within its performance specification.

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