What is Lighting Color Temperature?

May 22, 2020

Light bulbs might not be the first things that come to mind on the subject of color. Lights are either bright or dim, right?

It turns out that brightness is only one measure of the illumination put out by various types of light bulb. Colors and temperatures work together to create another way of evaluating how different LED lights will work in different situations. They become lighting color temperature — a system for measuring the whiteness of light, as expressed in units called kelvins.

The LED experts at TCP break down the meaning of lighting color temperature, the science behind the Kelvin color temperature scale, the type of mood created by warm light vs cool light, and how to achieve a desired lighting effect by choosing the right light bulb color temperatures.

Color Temperature Definition

For this discussion, temperature is not about heat. That may seem confusing — until you think about the way interior designers talk about colors. They say things like, “The brown tones in the woodwork really warm up the space,” and “the cool gray tiles make the kitchen feel fresh.”

They’re not talking about literally changing the ambient temperature in the room. They’re referring to the idea that some colors remind us of warmth, like red and yellow, while others remind us of coolness, like blue and green.

Color temperature, by definition, is an assessment of how far a light skews toward a warmer or cooler visual effect. In other words, lighting color temperature measures how much red (on the warm end) or blue (on the cool end) is present in a non-colored source of light. These measurements are expressed in units called kelvins, denoted by an upper-case letter K.

The Science Behind Lighting Color Temperature: Kelvin Scale Explained

The Kelvin Scale has been the scientific community’s preferred method of measuring temperatures since the mid-1950s. It’s different from the scales we commonly use for weather — Fahrenheit and Celsius — in that it is based on a calculated “absolute zero,” or the coldest possible temperature for any matter, as opposed to more arbitrary parameters. It is named for the British physicist and mathematician who developed it from the Celsius scale, William Lord Kelvin. It is denoted by an upper-case letter K after the numbers that indicate a temperature’s position above absolute zero.

Kelvin Color Temperature Scale

Less than 2000K: dim, yellowish light, close to candlelight

2000K-3000K: warm light with hints of yellow

3100K-4500K: bright, neutral white light

4600K-6500K: bright blue-white light (daylight = approx. 5200K)

6500K and up: very bright, bluish light

Correlated Color Temperature Scales

Translating the numbers on the Kelvin scale to the color temperature scale is where the whole thing can get a bit confusing. That’s because the color of light does not equal the heat from a light source. The full name is the Correlated Color Temperature (CCT) — and the word “correlated” and its mathematical definition are crucial. It denotes a relationship between the two measuring systems but not a one-to-one replication.

The Correlated Color Temperature Scale takes the kelvin units of measure and uses them to describe the color of light by turning the Kelvin Scale upside down. Where higher numbers indicate hotter thermal temperatures on the Kelvin Scale, they indicate cooler colors on the Correlated Color Temperature Scale. And this lines up with the way artists and designers discuss colors — and the way TCP lighting engineers talk about warm light vs cool light in terms of correlated color temperature.

Lighting Color Temperatures for Mood and Ambiance

You already know intuitively that lighting can change the way a space feels. Just walk down the stairs into a dimly lit basement or step into a sunlight-filled atrium — the former feels cold and creepy while the latter brings about feelings of warmth and happiness, regardless of the ambient temperature in the room.

These are extreme examples, but the point is that you can use this system of light bulb color temperature to create the mood or ambience you desire in just about any space. Start with a baseline of daylight color temperature, which is right around 5200K, then adjust down to make a room seem warmer and cozier, or adjust up to create an energetic, vibrant vibe.

Still confused? We’ve got your back. Here’s your primer for choosing the types of light bulb colors that elevate and personalize your home or workplace with warm light vs cool light.

Warm Light Colors

Light bulbs labeled in the 2000K to 3000K range on the lighting color temperature scale deliver illumination that is called “warm white.” Subtle red and yellow hues from these lights are more flattering to skin tones and clothing, making them popular in spaces meant for relaxing and socializing.

Choose 2700K light bulb color temperatures for residential applications like bedrooms and living rooms, and for commercial spaces where coziness counts, like quiet coffee shops and intimate wine bars. TCP’s Shape Filament Lamps offer a uniquely stylish look and a warm glow in both indoor and outdoor spaces. Our High Lumen Filament Lamps replace HID metal halide and corn cobs with a wide beam angle, versatile size and no ballast requirements in a wide range of lighting color temperatures. Many LEDs now offer dimming capabilities without the hum or flicker that used to be a problem, allowing you to switch up the ambience with minimal effort.

Move up to a more neutral “soft white” color temperature of 3000K in areas where higher visual acuity is required. At home, that means the laundry room, home office and guest bath. Commercial spaces that benefit from a neutral lighting color temperature include retail boutiques and wine bars.

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aesthetic lighting and functional lighting with ambient lighting
aesthetic lighting and functional lighting with ambient lighting

Cool Light Colors

As the kelvins go higher, the light bulb color temperature cools down. Lighting color temperatures in the 3100K to 4500K offer higher contrast than warmer options, making them great for areas where detail and clarity are a priority.

Opt for a light bulb color temperature of 3500K in living rooms to bring a lively feel to earthy décor. Bump it up to 4000K for cool crispness in residential kitchens and bathrooms. Commercial kitchens, cafeterias and large offices get a vibrant vibe from lighting color temperatures in the 4500K range.

For maximum brightness and safety, choose outdoor LED lighting that delivers the daylight color temperature of 5000K. Whether they’re for your backyard, a parking garage or the walkways around your business, these higher-kelvin light bulb colors provide a vivid, slightly bluish lighting color temperature.

Tips for Achieving Desired Lighting Effects Using Different Color Temperatures

1.) Avoid relying on a single light source in most rooms. Opting for a combination of lighting types —ambient, task and accent — helps eliminate glare and shadows while supporting any space’s functionality.

2.) Consider the importance of high CRI lighting for spaces where color accuracy counts, like galleries, schools, healthcare facilities and retail stores.

3.) Opt for dimmable LED lighting options in multi-use spaces, like office meeting rooms and home game rooms, to easily adjust the ambience from brightly cool color temperatures to softly warm color temperatures.

4.) Choose lighting with health benefits like reduced blue light spikes or built-in air purification to get more from your illumination than warm light vs cool light.

Harness the Power of Lighting Color Temperature with TCP

TCP is committed to helping you get the most from the lighting in every situation. Whether you’re choosing light bulb colors for your home or using the Correlated Color Temperature scale to design human centric commercial lighting, you’ll find energy-efficient, cost-effective TCP options that are also stylish and versatile. Contact us today for help choosing a light bulb color temperature, pricing your project, locating a TCP distributor, researching LED rebates and more.

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