Color Temperature

Defining Color Temperature

The lighting industry today offers lights featuring an exceptionally wide variety of color choices in order to suit as many different applications as possible. In order to quantify the specific color of a light, a color temperature scale was developed using Kelvin (K) as its unit of measurement. This has now become the industry standard and is used globally for all lighting applications. Formally known as Coordinated Color Temperature (CCT), this scale ranges from 1000K all the way up to 10,000K, with most commercially available lighting units falling within the 2500K and 6,500K range.

The lower end of this scale has a “warmer” feel to it, due to the characteristic red or orange hue. On the other end of the scale, higher Kelvin ratings tend to have a “cooler” feel with a white and even blue hue. This general range of color temperatures work well for a wide array of applications, with certain ones requiring specific Kelvin ratings and other applications being more flexible for a wider Kelvin range.

Kelvins and Color Temperature Scale

As established earlier, color temperature is measured in Kelvins, with the full color temperature scale ranging from 1,000K to 10,000K. Natural sunlight falls in the range of approximately 5,000K to 6,500K depending on the time of day and weather conditions. Generally speaking, most if not all commercial and industrial lighting falls into this kelvin range because of its versatility as well as its very close approximation to sunlight. In order to help illustrate this, we have created the below graphic that illustrates the overall kelvin range typically seen in artificial lighting as well as the equivalent types of lights that correspond to these ranges.

A chart showing the various color temperatures available in tube lighting. This details the purpose and applications of several of the most commonly used color temperatures in LED tube lights.

How Is Kelvin Measured?

Understanding the concept of using Kelvins for measuring color temperature is pretty straightforward, however actually measuring the specific kelvin temperature of a light source that is unknown is a bit more tricky. Because the Kelvin Scale (K) uses temperature as its form of measurement, the color of a light described in kelvins is actually a measurement of the temperature required to heat a black body radiator to achieve that specific visible color hue.

As an example, when a piece of steel is heated, it glows at different color hues at different temperatures. This will progress from a red or orange hue to a yellow and then a white or blue hue as the temperature increases. These color hues produced from heating the steel in this example cover most of the color temperature range visible to the human eye and are coordinated with the equivalent temperature in Kelvins (Celsius + 273) required to heat them to each specific color. It is upon this principle that all color temperature measurements in the lighting industry are founded.

Color Temperatures by Application

There are a wide range of color temperatures available on the market today, which can be daunting for those who are unfamiliar with the purposes and reasons behind each color choice. Essentially, different color temperatures are chosen for different applications in order to achieve differing lighting goals. This can range from selecting a color temperature to set a certain mood, such as a warm white light for relaxation, or selecting another for increased awareness and visibility, such as a light with a daylight color temperature. Below is a list of the most common color temperatures available in modern LED lighting.

Warm White
Considered to be the most relaxing color of all types of lighting, this was at one time the most common color of lighting in the world regardless of application. This is due to the fact that its temperature range of 2500K to 3300K is the natural range of color produced by not only candlelight and lanterns but also incandescent bulbs which dominated the lighting industry for nearly a century. Because it falls at the bottom of the color spectrum, it produces a noticeable red or orange hue.

Although the incandescent bulbs this color temperature is most closely associated with have largely been supplanted by more modern lighting technologies, this color temperature is still available and widely used. Most LED lights are available in this color temperature and it is regularly seen in both residential and retail applications whose goal is to achieve a cozy and inviting atmosphere for guests and customers. Lamps, chandeliers, bathrooms, living rooms and dining rooms are the most common residential applications for this color, with specialty product displays making up the bulk of retail use.

Cool White
Considered to be the middle of the road color temperature, this is a noticeably whiter form of light that falls just below the kelvin range where blue light is seen. Its range of 3500K to 4500K is most commonly seen in fluorescent lighting used in offices, warehouses and commercial and industrial settings. Because it has less of an orange or red hue, it does less to relax and instead provides more stimulation to individuals, raising their alertness.

Cool white is by far the most popular color temperature choice in today’s cost conscious business environments, especially large operations such as commercial and industrial facilities. Its stimulating effect on workers is noticeable when measuring efficiency – which helps to improve the bottom line. It is also a popular choice for certain residential applications with high foot traffic where increased awareness and visibility is important, such as entryways, stairways, porches and garages.

Hitting right at the top of the color temperature range of commercially available lighting, this color temperature range has a blue hue and ranges from 5000K to 6500K. Because of its close approximation to the color temperature of actual daylight, it produces the highest level of stimulation to individuals, resulting in maximum situational awareness and visibility.

Lights in this color temperature range are seen throughout all different types of residential, commercial and industrial applications. Because this color range most closely approximates natural sunlight, it is a popular choice for individuals who suffer from seasonal depression in locations that lack sunshine for significant periods of time. It is also commonly used in commercial and industrial applications due to its ability to provide the best color rendering possible out of the entire Kelvin spectrum, which significantly improves visibility and safety. In fact, this increase in visibility is so large that most if not all newer motor vehicles come equipped with headlights in this color range.

LED Tube Color Temperatures

There are a broad range of LED lighting fixture types and styles available on the market today. However, by far the most popular of these are tube style lights, serving either as retrofits for existing fluorescent light fixtures or as completely new installations. Due to the flexibility inherent of their design, they are used across a wide range of applications. These include commercial users such as retail stores and offices, as well as industrial facilities such as warehouses, manufacturing plants and other large scale operations. Due to the wide variety of applications tube lights are used in, they are available in a range of different color temperatures. Below are some of the most popular tube lights used today, with their most commonly available color temperatures.

U-Bend LED Tubes – Intended as replacements for existing u-bend fluorescent bulbs, these tubes come in a color temperature range of 4000K to 5000K. With a standard aluminum heat sink and a shatterproof plastic lens covering the LED chips, they are exceptionally durable and long lasting and make a great retrofit for users who do not desire to completely replace their existing u-bend fixtures.

4 ft. LED T8 Tubes – By far the most popular tube lights on the market, T8 style LED tube lights are available in two primary versions. These are the NX-Series, compatible with double ended wiring, and the X-Series which is compatible with both single and double ended wiring configurations. Either of these models can be used with an existing ballast, or can be used with a fixture that has been wired to bypass the ballast. Available in 4000K and 5000K color temperature ranges, these T8 LED tubes will satisfy practically any application requirement.

4 ft. LED T5 Tubes – Designed a drop-in upgrade for those who have already invested in T5 fixtures, these LED tube lights are intended to work with existing ballasts. They are available in a 5000K color temperature which is by far the most common color hue seen in applications using T5 fixtures.

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