White LEDs in architectural lighting have boosted lamp efficiency in recent years. Retailers promise a huge improvement in luminous efficacy. Claims like this are unfounded.
What affects luminous efficacy and how efficient is a white LED? Recently, LED manufacturers have competed on luminous effectiveness. No effort has been made to standardize luminous efficacy and operating circumstances. We often uncover interpretations that planners and designers cannot understand.
DIAL calculated the theoretical maximum luminous efficacy of several spectra.
White LEDs' theoretical maximum luminosity
The retina has 7 million red, green, and blue receptors. Cones perceive color. The majority (60%) are green receptors. Despite having the same radiant strength, humans see green as brighter than red and blue.
Human eyes adapted to light have maximal relative spectral sensitivity at 555 nm. The human eye perceives green light at 555 nm as brightest. The theoretical maximum luminous effectiveness at 555 nm is 683 lm/W. The expert uses photometric radiation equivalent Km. In actuality, this figure cannot be reached since 1 W of physical radiant power would be translated loss-free into visible light.
Despite being the most efficient, monochromatic green light is unsuitable for most lighting applications. The planner prefers white light with diverse color temperatures and good color rendering. However, adding visible field wavelengths (380–780 nm) to the spectral distribution will lower the theoretical maximum luminous efficacy.
Despite being the most efficient, monochromatic green light is unsuitable for most lighting applications. The planner prefers white light with diverse color temperatures and good color rendering. However, adding visible field wavelengths (380–780 nm) to the spectral distribution will lower the theoretical maximum luminous efficacy.
Farewell to the notion of significant progress in luminous effectiveness.
In the forthcoming years, a significant improvement in possible luminous effectiveness akin to that observed in the initial years following the mass manufacture of white LEDs is unlikely. The trajectory of the peak luminous efficacy of newly created items is gradually stabilizing.
The average luminous efficacy of LED luminaires is expected to enhance further, as there are already luminaires available with a luminous efficacy of 50 to 70 lm/W that can still be optimized. This fact is clearly demonstrated in the measurements conducted by DIAL in its recognized laboratory during the past few years.
Undoubtedly, the LED is an efficient source of illumination. Nonetheless, the LED is constrained by physical restrictions regarding luminous efficacy. The theoretical maximal luminous efficacy is contingent upon the specified spectrum. Significant advancements cannot be anticipated in the present era.
Assertions such "In a few years, white LEDs will attain a luminous efficacy of 500 lm/W!" are fundamentally erroneous, as this is physically unattainable.
A reminder for planners: Exercise discernment and consistently apply your judgment.
Shenzhen Benwei Lighting Technology Co., Ltd was established in 2010. It is a national high-tech enterprise integrating design, R&D, production and sales of indoor and outdoor lighting products and also can do OEM ,ODM .For more details about our offerings, please contact us at bwzm18@ledbenweilighting.com
