LumenPriority.org has announced the launch of its web site and interactive blog to present, discuss and explore the potential of applying feedback control of LEDs within solid-state lighting systems to stabilize lumen delivery through current regulation to compensate for light loss factors. This is the latest brainchild from friend and colleague Kevin Willmorth of Lumenique.
Conventional lighting design requires that standard lighting calculations include some overcapacity to deliver greater than desired initial light levels to compensate for gradual light loss experienced by all lighting systems as they age. The result is a higher level of energy consumed by this overcapacity, not to mention the additional capital installed to enable the overcapacity.
The “lumen priority” concept is to use current control technology to LED products to produce a set steady-state delivery of light output over the life of a luminaire. So the luminaire would produce less light than it is able initially, and as depreciation occurs, light output would be increased, maintaining a steady light output. This saves energy and can extend the life of the LEDs through dimming throughout much of its life–25-55%, in fact, according to Willmorth.
It sounds a lot like fluorescent lumen maintenance dimming, which used to be much more viable until lamp lumen maintenance improved dramatically, but there appears to be quite a bit of utility here for LEDs. LEDs have a higher lumen depreciation rate and since lumen maintenance is directly related to lamp life for LEDs, dimming extends lamp life with LEDs while saving energy.
As you can imagine, there are a number of ways this can be accomplished. Should the luminaire be programmed based on the projected lamp lumen depreciation rate? Should there be some type of feedback loop that measures the light output of the luminaire? Or should there be photosensors that measure light levels, not light output, adapting the luminaires to all lighting conditions, including daylight? LumenPriority.org seeks to facilitate an exchange of ideas on how to best apply the approach, including showcasing manufacturers that have the capability right now to get this done.
To learn more, click here.
Conventional Lighting Calculation, Lumen Impact and Energy Balance
The LUMENPRIORITY Approach Using SSL Technology
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