Although people overlook this fact, they should always consider the difference between color temperatures. This is one of the most significant factors when it comes to installing new LED lighting fixtures.
Any light, including LED, that produces the same amount of lumens can look strikingly different based on the color temperature of that fixture.
The difference is very significant, even on the biological level. Human brains are configured in such a way that they respond differently to certain light and colors.
We feel relaxed and calm under warm-toned colors, whereas we become productive under cool-toned colors. The color temperature of lights has a huge impact on us.
Understand the Lighting Spectrum
High-quality light comprises diverse kinds of light colors. One can spot this through the naked eye. For instance, you can easily see a multi-colored rainbow when the light is split by tiny water droplets that act as prisms.
Or even, you can simply make your own rainbow through a CD. All you need to do is to hold a CD in light, the CD’s prismatic layer will start breaking up the light into its fundamental colors.
The visible colors of light are Violet, Indigo, Blue, Green, Yellow, Orange, and Red. It is shortened as VIBGYOR. In the VIBGYOR spectrum, the least energetic light is red and the most energetic one is violet. However, there are various other forms of light on the spectrum, which one cannot see.
This includes infrared light and ultraviolet light. As their terms suggest, ultraviolet comes after violet light on the spectrum and infrared comes before red.
So, LED lamps are designed especially for offering a good quality of light. These lights create a complete spectrum of light featuring all the visible light colors. Humans cannot see UV or infrared lights as these lights are not visible. Thus, these lights are entirely useless to human eyes.
Even, both UV and Infrared lights may damage paintings and art objects at your place. Also, UV light is even considered dangerous for genetic material. As compared to LEDs, other kinds of bulbs, such as Incandescent lamps, produce 95% of the light output in the invisible light range. Thus, this makes such bulbs highly energy inefficient.
How Do Humans See Colors?
If you do not know, what we see as white light contains all the diverse light colors actually in equal proportions. So, when the white light strikes a thing, most light colors get absorbed and only some are reflected.
Thus, the color of a thing is actually determined by the light color it reflects. It is quite important that a lighting source needs to emit light with all the light colors in it. As a result, we will be able to perceive the color accurately.
If a lighting fixture does not bring out a specific light color, things of that color will be invisible in the natural shade. That’s why sodium lamps are pretty bad at replicating accurate colors.
This is because sodium light is primarily made of yellow light, which falls into the narrow-spectrum light. Thus, when you place a thing of a color other than yellow under a sodium light, it reflects all the different yellow shades.
This offers nearly every object under these lighting sources a sickly hue. On the other hand, LED lights produce only natural colors. This is because the light comprises a perfect spread of all colors. Plus, there is a well-balanced light.
Color Rendering Index and Light Spectrum
Color Rendering Index or CRI measures how precisely light from a lighting source is going to reproduce colors. Although there is a difference between CRI and color temperature, these two terms are correlated to each other.
To know more about CRI, head to the CRI article. However, for now, it is just significant to understand that CRI refers to a measurement of the light quality emitted through a lamp.
On the other hand, a higher CRI does not always correlate with a perfect color temperature.
Incandescent light is the lighting source having an ideal CRI. This light serves a 100 index as the spectrum offers all the color spectrum wavelengths. Incandescent light lamps can be compared to sunlight, which is a natural lighting source having a 100 CRI.
However, LED systems and products are different altogether. If you look at pictures produced using a LED projector, the produced colors are far more superior to older technology. So, LEDs are a perfect lighting source, which can be used in warehouses, schools, and factories.
Visual tests clearly show that the CRI definition has to be revised. Scientists ask observers to give ratings to color schemes. These ratings are used for defining the CRI of a bulb under various lighting sources.
The comparisons of LEDs with bulbs having a higher CRI are quite surprising. The observers have an impression of equal light quality despite LED lights feature a lower CRI than other bulbs, like incandescent lamps.
Light Spectrum and Lighting Devices
The reason behind a perceived CRI is actually color temperature. An incandescent lamp, that produces warm yellow light, does contain all the light colors. However, these colors are not present in equal proportions. An incandescent lamp lacks violet, blue, and green lights.
Thus, when you place violet, blue, or green objects under the light of these bulbs, the colors get distorted. By contrast, LEDs produce a well-balanced, complete light spectrum. Here, the lights reproduce the natural colors of things.
Sodium lamps feature a very poor CRI around 25,
Mercury lamps have a CRI of 50, and
HIDs feature a CRI of 72.
The CRI of LEDs and CFLs may vary with a light color, however, generally lies between 75 and 85.
Color Rendering Index or CRI of a lighting source is comparable across different sources that function at the same temperature. LEDs work at a very low temperature if compared to incandescent bulbs.
That’s why the CRI of 85 actually underestimates the performance of LEDs. So, there are plans for taking another look at the CRI standard for reflecting the actual reality of the lighting world.
As mentioned above, the ‘color temperature’ term defines the temperature of an object through which it emits lights. These objects are modeled through a black body radiator. When you increase the temperature of this black body, it begins to emit visible colors in a continuous light spectrum.
So, the filament of an incandescent bulb featuring 60 Watts heats up to around 3000°F. Thus, the bulb emits the light with a 3000K color temperature.
Most of our artificial lighting sources do not produce light by heating up materials until they glow, such as incandescent lamps. Rather than producing a continuous light spectrum, these lights create an assortment of color emission lines.
What Does Correlated Color Temperature Mean?
LED lighting sources employ a detailed chart for assigning a correlated color temperature (CCT) rather than using the heated filament’s color for determining the color temperature. One can calculate CCT based on the black body radiator’s color temperature. Check out the chart below to see how this works!
The curved, black, line is called the “Black Body Curve.” This curve represents the object’s color temperature, which is heated until it releases light. The lines that intersect the black body curve show the point range on the chart. So, this will result in a particular color temperature.
For instance, A Metal Halide bulb having the Coordinates:
A=0.396, B=0.402 shows that the bulb has a 3800K Color Temperature (signified by the red “A”)
Importance of Color Temperature
Color temperature is particularly important in photography and desktop publishing. Differences in color temperature can result in variations in color rendering.
In homes and offices, color temperature of lights is important as different colors of light have different psychological impacts and are designated as ‘warm’ or ‘cool’. Ironically, the so-called ‘warm lights’ have a lower ‘Color Temperature’ while the ‘cool lights’ have a higher ‘Color Temperature’. Warm and cool thus refers not to the color temperature but to psychological attributes of lighting. The light from wood burning fires and incandescent bulbs is yellowish in color.
The human mind, conditioned by thousands of years of social evolution, accepts yellow-ish light as warm and inviting. On the other hand, day white light is associated with cleanliness and efficiency – as in hospitals. IT is also depending on cultural and regional backgrounds as people form countries nearer to the equator prefer cold white light sources than warm white lights.
The choice of light color temperature is governed by the look you wish to create in an area. Lights of different color temperature are described by their similarity to known sources or with typical adjectives. The table below can help you choose the right lamp for your needs
|Color Temperature (Kelvin)||Characteristics and Examples||Describing the Light||Best Uses and Locations|
|2700-3200K||Incandescent bulbs, yellowish light is best for accentuating skin tones and the wooden objects||Friendly, warm, inviting, intimate, relaxing||Homes, boutiques, reception areas, Hotels.|
|4000-4500K||Like early morning sunlight, Xenon headlights for cars||Neat and clean, Natural tone||Offices, School Lights, Outdoor Areas, Hospitals, Commercial Spaces|
|5500-6000K||Daylight, Flashlights and Metal Halide||Crisp light, efficient, brightly lit, natural outdoor||Shops, Factories, Printing Businesses, Warehouses, Parking Lots, Outdoor Area Lighting|
|7000-7500K||Best contrast but least flattering to the skin.||Bright light, bluish light||Special applications needing high light intensity and good color rendition like art Galleries, museums, showcases for precious stones and jewelry|
Lower color temperature intensity makes the light appear warmer that goes on to be redder as the temperature goes down further. On the other hand, light appears cooler and further bluer with high temperatures.
All the fixtures for both commercial and residential lighting systems have color temperatures ranging between 2000-6000K with 2700K and 3500K being the most popular ones.
This indicates the preference for warmer light fixtures for residential spaces. At the same time, cooler fixtures are preferred for the industrial and commercial spaces among their various application needs. This indicates their biological and aesthetic appeal.
What lights do I need – warm or cool?
The warm color lights are usually good for the residential spaces as they make the ambiance appear more welcoming and comforting. Marking a contrast, cooler lights work better for the industrial and commercial spaces.
This is because the cooler lights help the workers feel better and be more productive by relaxing them. However, what makes this difference of light suitability occur between the residential and commercial spaces? The answer to this lies in the biological nature of lights that we mentioned above.
The cool fixtures produce brighter white light that causes the bodies exposed to it to release serotonins. These neurotransmitters alert the senses of people. This is similar to the way one feels more awakened when exposed to sunlight and how one finds it difficult to sleep after having stared at the screen continuously for a while.
On the other hand, warmer lights cause the exposed bodies to release melatonin. This hormone regulates the circadian rhythm or the natural body cycle of sleep-wake to help people feel relaxed and sleepy.
This explains why warmer light fixtures are chosen for residential spaces and areas like living rooms and bedrooms specifically. These lights cast a relaxing and comforting effect on people and help them rest better. The places in homes that do better with cool fixtures include bathrooms and kitchens.
At the same time, bathrooms are fitted with even cooler toned light fixtures. This increased difference in contrasting and color rendering works better for spaces like bathrooms than the common cool and neutral light fixtures that serve other places better.
The usage of warm lights is not restricted to the residential spaces only. These fixtures are still fitted in various commercial spaces like reception areas, lobbies, hotels, restaurants, etc. The primary idea behind this is that these lights can be used in any commercial space that needs to make its visitors feel relaxed and comfortable.
On the other hand, cooler lights serve the purposes of high contrast and boosted productivity better. The major use of cool LED lights is done in the office buildings as the bluer toned lights help to increase the workers’ productivity. However, there are many other particular spaces where cool lights become essential than just important. Such places include workshops and factory floors that need brighter lightings.
A comparison of the LEDs with high-pressure sodium and metal halides
Well, this isn’t even a fair competition. LED lights have distinctive technological built that makes them produce better quality light. Compared to it, other lights perform best to their limited capabilities. High-pressure sodium lights have CRI between 20-40 and a color temperature of 2300K. These factors determine the warmth or yellow hue of the light produced.
Metal halides do better than high-pressure sodium but fall back when compared to LEDs. Their CRI is better than high-pressure sodium but color temperature is almost similar. However, it is also a fact that the high CRI doesn’t remain constant throughout the life of lights. After you purchase the lights, the light quality will start downgrading slowly with time.
Lastly, the LEDs appear with the best results as they let you customize both color temperature and CRI. You can choose to either buy the LEDs with pre-determined CRI or the ones with remotely controllable CRI.
The most popular LED color temperatures
5000K color temperature
The lights belonging to this color temperature range produce a whitish blue color and are mostly used for accurate color representation for the industrial and commercial spaces where it’s crucially required.
The lights of this range have a crispier and brighter quality. The color contrast they generate makes even the smallest of details stand out. Such differentiating detailing is essential for places like exam rooms, hospital surgery rooms, etc. and these LED lights must be used there.
4000K color temperature
The lights belonging to this color temperature range produce a neutral white color and one of the most profoundly and variously used lights. This color temperature gives a balanced tone between yellow and blue to the LED lights.
This gives two benefits to the exposed bodies- alertness span that lasts for a longer time and reduction of the risk of eye strain from blue lights. This light works better for commercial spaces including offices, hallways, hospital offices, retail stores, etc.
3000K color temperature
The lights belonging to this color temperature range produce a yellowish-white color. The slight warmth of these lights gives a cozy and relaxing effect to the spaces that make them ideal for usage in commercial spaces that need a welcomingly comforting ambiance. These lights, thus, are most commonly used in spaces like hotel lobbies, spas, and similar other places.
About the Author
Cory Peterson is Director of Sales & Marketing at LED Lighting Supply where he focuses on improving customer experience and revenue operations. Cory writes about commercial & industrial lighting, along with topics important to contractors and facility managers. In his free time, Cory enjoys traveling, snorkeling, exercise and cooking.