Question 1

What's the requirement of CCT from Darksky?

Accepted Answer

What correlated color temperature requirements must lighting fixtures or designs meet to earn “DarkSky Approved” certification? In fact, DarkSky has specific requirements for CCT: the correlated color temperature (CCT) of a lighting fixture must not be greater than 3000K. It also recommends a color temperature of 2700K or less, which produces a warm yellow light that is more effective at reducing light pollution and minimizing ecological impacts. For example, the ZGSM Rifle series street lights with 2700K LEDs have got the Darksky approval.

As mentioned earlier, lower CCT values often lead to lower luminous efficacy, so this recommendation must be considered holistically. ZGSM feels that some of these requirements are particularly necessary for some nature reserves (sensitive areas protecting sea turtles). The emission wavelengths of these luminaires are mainly concentrated at 560 nm or higher, which helps to reduce the disruption to sea turtles. Darksky sports fields should not be higher than 5000K.

Question 2

Color temperature or correlated color temperature?

Accepted Answer

A perfect blackbody is a theoretical object which absorbs all light and reflects none . When heated consistently from absolute zero , the blackbody emits light in the order of red , yellow , white and bluish-white . If a light source has the same spectrum and color as the radiation of a blackbody at a given temperature, then the blackbody's Kelvin temperature (which is also called color temperature) is the light source's color temperature. However, many modern light sources are different from traditional ones (i.e. blackbody-like sources such as incandescent lamps and natural light), hence the concept of color temperature in the strict sense. The spectra of artificial light sources (e.g. fluorescent lamps, energy-saving lamps, and LEDs) are not exactly the Planckian blackbody spectrum; therefore, a standard color temperature cannot be defined for them, leading to the introduction of the concept of correlated color temperature.

Question 3

How can you quickly determine whether DUV is positive or negative, and what the correlated  color temperature is?

Accepted Answer

You can quickly obtain this information by consulting a photometric test report or an LM79 report. If you have results for “Nominal CCT quadrangles by Goniophotometer method,” you can also make a quick determination by looking at the graph. If the light source’s color coordinates lie above the blackbody locus on the chromaticity diagram, then Duv is positive; if the light source’s color coordinates lie below the blackbody locus on the chromaticity diagram, then Duv is negative. To determine the correlated color temperature (CCT), you can check the color coordinates in Nominal CCT Quadrangles and get the result. Of course, you can also use the McCamy’s empirical formula to calculate the CCT based on the color coordinates.

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Correlated color temperature Kelvin / K value in LED lighting

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LED Street Light

High Mast Light

Led Flood Light

Solar Flood Light

LED High Bay Light

LED Tunnel Light

LED Garden Light

Led Bollard Light

Solar Street Light

LED Traffic Light

LED Canopy Light

Lighting Accessories

Smart Systems

Simulation Design

Smart Financing