Although it is often overlooked, the difference between LED color temperatures is one of the most important things to keep in mind when installing new fixtures.LED lights, or any lights for that matter, that run the same wattage and output the same lumen count can look wildly different depending on their color temperatures. This difference is extremely important, even on a biological level. Our brains are configured to respond to certain colors of light in different ways. Warm-toned colors make us feel calm and relaxed while cooler toned color encourages productivity. Clearly, the color temperature of a light makes a big impact.

What is Color Temperature?

First things first, we’ll need a definition of what color temperature is. Although there is a long history behind the term, involving many experiments and 18th-century physicists, there’s a very easy way to define it. 

Color temperature is a description of the warmth or coolness of a light source. When a piece of metal is heated, the color of light it emits will change. This color begins as red in appearance and graduates to orange, yellow, white, and then blue-white to deeper colors of blue. The temperature of this metal is a physical measure in degrees Kelvin or absolute temperature. While LEDs do not exactly mimic the output of this piece of metal, we utilize the correlated color temperature (or Kelvins) to describe the appearance of that light source as it relates to the appearance of the piece of metal (specifically a black body radiator).

Understanding the Light Spectrum

Solarrays

Good quality light is composed of different colors of light. You can see this with the naked eye, as a multi-colored rainbow is visible when light is split by small water drops acting as prisms. Or, you can create your own rainbow by using a CD. When you hold it in light, the prismatic layer of the CD breaks up light into its constituent colors.

Violet, Indigo, Blue, Green, Yellow, Orange, and Red are the visible colors of light. In this spectrum, red light is the least energetic and violet light is the most energetic of the lot. However, there are also many forms of light on the light spectrum that are not visible to us. One of these is infra-red light. As their names suggest – Infra-Red light comes before red light on the spectrum and Ultra Violet comes after violet.

Because LED bulbs are designed to offer a high quality of light, they produce a full spectrum light, with all visible colors. Human beings do not need Infrared or UV lights because they are invisible and therefore completely useless to our eyes. In fact, both Infrared and UV light may damage art objects and paintings in your house, and UV light is considered harmful to genetic material. In comparison to LEDs, other types of bulbs, like Incandescent bulbs, produce 95% of their output in the invisible infrared range. This makes them very energy inefficient.

How Do We See Colors?

What we perceive as white light actually contains all the different light colors in almost equal proportions. When white light strikes an object, most colors of light are absorbed and a few are reflected. The color of an object is determined by the color of light it reflects. It is important that a light source emits light with all the colors of light in it so that we can accurately perceive the color. 

If a fixture does not produce a particular color of light, objects of that color will not be visible in their natural shade. This is why sodium lights are so bad at reproducing accurate colors. Sodium light is a narrow-spectrum light that is made of primarily yellow light. When an object of a color other than yellow is placed under sodium lights different shades of yellow are reflected.

This gives almost every object beneath these lights a sickly hue. LEDs produce natural colors as the light is well balanced and contains an ideal spread of all light colors.

Light Spectrum and Color Rendering Index

The Color Rendering Index is a measure of how accurately light from a source will reproduce colors. And although color temperature and CRI are different measurements, they are closely correlated. For more information about CRI, you can read our CRI blog. But for now, it’s just important to know that CRI is a measurement of the quality of light emitted from a bulb. 

However, a high CRI doesn’t always correlate with ideal color temperature. 

Incandescent light is the light source with the best CRI. It serves an index of 100 because the spectrum provides all color spectrum wavelengths. An incandescent light bulb is comparable to sunlight, which a natural light source with 100 CRI.

LED products and systems are in a different league altogether. Looking at images produced by a LED projector, the colors produced are much superior to older technology. LEDs are an ideal lighting source for applications such as factories, schools, and warehouses. 

Visual tests have shown that the definition of CRI needs to be reviewed. Scientists asked observers to rate color schemes, which are used to define the CRI of a lamp, under different light sources. The comparisons of LED with lamps of a higher CRI have been surprising. The observer has a visual impression of equal lighting quality despite LEDs having a lower CRI than incandescent bulbs.

Cri

Lighting Devices and Light Spectrum

The reason for this perceived CRI, is color temperature. Warm yellow light produced by an incandescent bulb does in fact contain all colors but, but not in equal proportions. Incandescent bulbs lack green, blue, and violet lights. So, when green, blue, or violet objects are placed under an incandescent bulb’s light the colors are distorted. LED’s by contrast produce a complete, well-balanced spectrum of light and natural colors of objects are reproduced.

  • Sodium lights have a very poor CRI of 25,
  • Mercury lights weigh in at 50 and
  • HIDs have a CRI of 72.
  • The CRI of CFLs and LED lights vary with light color but generally lie between 75 and 85.

The CRI of a light source is comparable across sources that work at the same temperature. LED lighting works at very low temperatures compared to an incandescent bulb. Thus the CRI of 85 underestimates their performance. Plans are afoot to take another look at the CRI standard to reflect the reality of the lighting world.

Color Temperature

As we mentioned, the term color temperature describes the temperature of objects by which they emit light. These are modeled through the black body radiator. When increasing the temperature of a “black body”, it starts to emit visible light in a continuous spectrum.

The filament of a 60W incandescent lamp heats up to about 3000°F, and as a result, the lamp emits light with a color temperature of 3000K. Many of our artificial light sources do not create light by heating up a material until it glows like an incandescent lamp. Instead of creating a continuous spectrum, they generate an assortment of color emission lines.

Kelvin Color Temperature Scale Chart

What is Correlated Color Temperature?

For LED light sources instead of using the color of a heated filament to determine the color temperature, they use a detailed chart to assign a correlated color temperature(CCT). CCT is calculated based on the black body color temperature. This is demonstrated in the chart below.

Cct Chart

The black, curved line is known as the “Black Body Curve” and represents the color temperature of the object that is heated until it gives off light. The lines intersecting the black body curve represent the range of points on the chart that will result in a specific color temperature.

For example, 

A Metal Halide lamp with the Coordinates: 

X=0.396, Y=0.402 shows that the lamp has a 3800K Color Temperature (marked by the red “X”).

What are color temperatures relative to LED Lighting?

 

Lamp Color Name

Color Temperature (Kelvin)

Characteristics and Examples

Common Adjectives Used to Describe the Light

Best Location

Warm White

2700-3200K

Similar to an incandescent bulb, yellowish light is best for accentuating skin tones and the color of wooden objects

Friendly, warm, inviting, intimate, relaxing

Homes, boutiques, reception areas, Hotels.

Natural White

4000-4500K

Similar to early morning sunlight, Xenon lamp for automotive use

Neat and clean, Natural tone

Offices, School Lights, Outdoor Areas, Hospitals, Commercial Spaces

Day White

5500-6000K

Typical daylight, Flashlights. Metal Halide

Crisp light, efficient, brightly lit, natural outdoor

Shops, Factories, Printing Businesses, Warehouses, Schools, Parking Lots, Outdoor Area Lighting

Cool White

7000-7500K

Best contrast but least flattering to the skin, may need mixing with light from a warm white lamp.

Bright light, bluish light

Special applications needing high light intensity and good color rendition like art Galleries, museums, showcases for precious stones and jewelry

The lower the color temperature, the warmer the light will appear, or the redder it will appear. The higher the temperature, the cooler the light will appear, or the bluer it will look.

In both the residential and commercial lighting world, almost all fixtures will be somewhere between 2000K and 6000K, with the two most common color temperatures being 2700K and 3500K. This is because warm fixtures dominate residential settings. But cool-toned lights have plenty of applications, the majority of which are in the commercial and industrial spheres. The reasons for this are both aesthetic and biological in nature.

Do I Need Warm or Cool-toned Lights?

In general, warmer colored lights are preferred in most residential settings because they give off a more relaxed and welcoming ambiance. On the other hand, in commercial and industrial settings, cooler fixtures work much better. Even workers notice a difference in their productivity under cool-toned lights. But why are warm fixtures better for residential installations, and cooler fixtures for commercial environments? This is the part where the biology we mentioned earlier plays an important role.

When exposed to bright white light and cool fixtures, the body releases serotonin, a neurotransmitter that usually makes people feel more alert. This response is why sunlight can make someone feel more awake and active, and also why it’s hard to fall asleep after staring into a computer monitor for a while. Alternatively, in the presence of warm light, the body releases melatonin, a hormone that helps regulate your circadian rhythm (the natural wake-sleep rhythm of the body) and encourages sleepiness. 

This is why warmer fixtures are reserved for most residential applications, like the bedroom or living room. In these settings, the warm light helps people relax and wind down for sleep and makes them feel more comfortable. The only places where white or cooler lights are typically preferred are in the kitchen and bathroom, and chances are if you walk into your bathroom, you’ll see that it’s lit in a cooler toned light than the rest of your home. In these spaces, the higher contrast and better color rendering than neutral and cool fixtures offer are much appreciated. 

But residential isn’t the only setting where warm lights are used. Warm fixtures are still preferred in some commercial settings, such as lobby and reception areas, and for businesses like restaurants and hotels. In general, any business that needs to make its customers feel comfortable will need warm fixtures in some areas.

However, cooler fixtures are needed in any setting where productivity and high contrast are needed. The single biggest application of cool LEDs is in office buildings, where bluer light can help boost worker productivity. But, in other more exclusive applications, like factory floors or workshops, the bright shine of cool-toned LEDs is more than appreciated, it’s essential.

Comparing LED to Metal Halide and High-Pressure Sodium

We’ll be honest with you, this isn’t a fair fight. LEDs were literally designed to have a higher quality light. Other bulbs are simply doing the best with what they’ve got. High-Pressure Sodium CRI is somewhere between 20 and 40, and the color temperature is around 2300K. These two factors produce a very warm (yellow) light that tends to discolor everything. 

Metal Halide fixtures fair a little better, but still, falter when compared to LEDs. Metal halide lights have a better CRI than HPS, but tend to run around the same color temperature. And, unfortunately, their higher CRI doesn’t remain consistent throughout the light’s lifespan. In fact, shortly after purchase, you’ll likely notice a difference in the light quality. 

LEDs, on the other hand, offer complete customization of both CRI and color temperature. This is usually decided before purchase, but some lights even come with a remote so you can adjust the color temperature, as needed.

The Most Common Color Temperatures for LEDs

5000K Color Range

Lighting that’s in the 5000K color temperature range is blue-white in color and it most often used in commercial and industrial settings where accurate color representation is extremely important. The quality of this light is bright and crisp. Small details stand out under this type of light because of the color contrast this crisp light offers. This LED color is best used in factories or other workplaces where details are important, like hospital surgery and exam rooms.

4000K Color Range

The 4000K color temperature range for LEDs is neutral white and also the most commonly used. This color temperature emits a balanced color tone that’s not too blue or too yellow. This helps to create an environment where employees can remain alert throughout the day, but without the strain blue light can sometimes cause the eyes. Spaces that would benefit from this type of light would be commercial spaces like retail stores, hospital offices and hallways, and office spaces.

3000K Color Range

LED lighting in the 3000K color temperature range is slightly yellow-white in color. This little bit of warmth helps to make spaces seem cozier, making it ideal for creating an inviting environment that’s perfect for commercial spaces. You’ll find this color temperature used most often in settings such as spas, hotel lobbies, and other areas that need a welcoming touch.

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