The Colour Temperature: Everything You Need to Know About Choosing the Right Light Colour

The colour temperature influences our well-being and our ability to concentrate. It also affects the quality of our sleep. It is therefore important to consider the appropriate colour temperature for the different rooms when planning lighting.

In this article, you will learn what is meant by colour temperature, what effects it has and what design options there are.

Definition of colour temperature

Colour temperature describes the colour of the light emitted by a light source. It is measured in Kelvin (K). Colour temperature does not indicate the actual temperature of the light source in degrees celsius. A low Kelvin value, such as 2700 K, corresponds to a warm light that appears yellowish-white and is often compared to the light of traditional light bulbs. A high Kelvin value, for example 6500 K, corresponds to a cool light that appears bluish-white and resembles daylight. 

Colour temperature affects the atmosphere of a room and can affect our mood. Warm white light can create a cosy and relaxing ambience, whilst daylight white light has a stimulating effect and promotes concentration

Are colour temperature and light temperature the same?

The terms colour temperature and light temperature are often used interchangeably, as they both describe the same physical property: the colouration of light, which is measured in Kelvin (K) and ranges from warm tones (low Kelvin values) to cool, daylight-like tones (high Kelvin values).

However, the term colour temperature is more precise and common, especially in lighting technology and photography. It refers to how the colour of light appears at different temperatures.

What is the difference between Kelvin and Lumen?

Kelvin and lumens are two different units of measurement that describe important properties of light but illuminate different aspects. Kelvin (K) refers to the colour temperature of the light and indicates how "warm" or "cold" the light appears. Lumens (lm), on the other hand, is a measure of the brightness or light output of a light source. The higher the lumen value, the brighter the light.

To put it simply, Kelvin describes the colour of light, while lumen indicates how intensely this colour shines.

The Kelvin scale and its meaning

The Kelvin scale is an important tool for describing and categorising the colour of light. It is based on the idea of a so-called "black body" that emits light in different colours when heated. The higher the temperature of the black body, the colder and bluer the light appears.

The Kelvin scale uses this relationship between temperature and colour to classify light sources based on their colour temperature. The Kelvin scale allows us to compare the colour temperature of different light sources and select the right light colour for different applications.

Light colours and their effect

The colour temperature of light has a significant impact on our mood and the atmosphere of a room. Choosing the right colour temperature ultimately depends on the function of the room and personal preferences. It is important to understand the different colour temperatures and their effect in order to design the lighting in such a way that it meets one's needs and creates a pleasant ambience.

Below are the different colour temperatures. In the table you will find the corresponding Kelvin number, the properties and examples of use.

Warm White (2000K - 3000K)

Warm white light is similar in colour to the light of a traditional light bulb. It creates a cosy and inviting ambience that invites you to relax. The high proportion of red light in warm white light contributes to this relaxing atmosphere and makes rooms such as the living room and bedroom particularly comfortable

Warm white light is associated with terms such as "cosy" and "homely". It can emphasize the effect of wooden furniture and is therefore well suited for rooms with wooden furnishings. In the hospitality industry, warm white light is often used to create a welcoming and relaxed atmosphere in dining rooms or waiting areas.

Neutral White (3100K - 4500K)

Neutral white light is characterised by a balanced proportion of red and blue tones. In contrast to the warm, yellowish light of warm white, neutral white appears brighter and more businesslike. This light colour creates a friendly and inviting atmosphere, but without being too stimulating. Therefore, neutral white is particularly suitable for rooms where balanced lighting is desired, which should be neither too relaxing nor too stimulating.

Typical areas of application for neutral white are hallways, kitchens and bathrooms. In the kitchen, neutral white provides good illumination of the work surfaces, while in the bathroom it provides clear and bright lighting for personal hygiene. Neutral white can also be a good choice in workspaces where concentration and attention are important, as it supports a businesslike and focused working atmosphere.

Cool white / daylight white (from 4600K)

Cool white and especially daylight white light is characterised by a high blue content and resembles the natural light of a cloudy day. It has a cool and clear effect, creating an invigorating and activating atmosphere. This light colour promotes concentration and attention and is therefore particularly suitable for work areas such as offices, offices or libraries. In contrast to warm white light, which has a more relaxing effect, daylight white stimulates activity and can help you feel more alert and energetic.

In rooms used for creative activities or tasks that require high concentration, daylight white can increase productivity and performance.

Since daylight white is similar to natural daylight, it can also be used indoors that receive a lot of daylight through windows to complement lighting and provide even illumination.

Light temperature and its influence on the biorhythm

The colour temperature of light has a direct influence on our circadian rhythm, especially on the sleep-wake cycle. This is because colour temperature affects the production of the hormone melatonin, which plays an important role in regulating our sleep. Warm light with a low colour temperature, similar to the light of a candle or sunset, promotes melatonin production and signals to our body that it's time to relax and prepare for the night. Cold light with a high colour temperature, on the other hand, such as the light of a cloudy day, inhibits melatonin production and signals to our body that it's time to be awake and active.

Therefore, the use of cold white light in the evening hours can disrupt our circadian rhythm and make it difficult to fall asleep because the production of melanin is suppressed. Conversely, using rather cold light in the morning can help us wake up faster and feel more energised.

It is therefore advisable to adjust the colour temperature of the light to the time of day to support the natural biorhythm. During the day, when we need to be active and focused, cool white light is a good choice. In the evening, when we want to relax and prepare for sleep, warm white light is more suitable.

How can you tell the colour temperature of light sources?

The colour temperature of bulbs can usually be determined by information on the packaging of the product. There, the colour temperature is given in Kelvin (K) to make it clear whether the light emitted is rather warm or cold. In addition to the numerical indication in Kelvin, descriptions such as "warm white", "neutral white" or "daylight white" are often found on the packaging, which characterise the colour temperature of the light.

How to measure colour temperature?

To determine the colour temperature of the light, you need a special measuring device, the so-called colourimeter or colour meter. This device analyzes light and breaks it down into its different colour components, similar to how a prism splits sunlight into its spectral colours. The colorimeter then measures the intensity of each colour component and can thus determine the exact colour temperature in Kelvin. This method is based on the physical principle that the colour of a glowing body changes with increasing temperature. For example, iron glows red when heated, then yellow and finally bluish-white. The Kelvin scale uses this relationship between temperature and colour to describe the colour temperature of light.

Can you change the colour temperature?

With some lamps and bulbs, it is possible to change the colour temperature. This usually works by dimming the lighting. The prerequisite for this is a suitable bulb and a dimmer. By dimming daylight white light in the evening, for example, a cosier atmosphere can be created in the living room. However, not every LED lamp is dimmable. Therefore, pay attention to the description of the products.

Colour Temperature for RGB Lights

RGB lights differ from conventional light sources in that they are not limited to a fixed colour temperature. By mixing the three primary colours of red, green, and blue, RGB lights can produce a wide range of colours, including different shades of white.

While the colour temperature of conventional lamps is given in Kelvin and describes the colour temperature of the light, the colour of RGB lamps is defined by the combination of the RGB values. Depending on how strongly the individual colour channels (red, green, blue) are controlled, different colour impressions are created.

For example, RGB lights can produce warm white light by increasing the red content and reducing the blue content. Conversely, by increasing the blue content and reducing the red content, daylight white light can be produced.

The ability to flexibly adjust the colour mix makes RGB lights a versatile tool for lighting design. They can be used for mood lighting as well as functional lighting.

By dynamically adjusting the light colour, RGB lights can, for example, simulate the course of the day or create different scenarios for different activities. So you can start in the morning with activating, daylight white light and switch to cozy, warm white light in the evening.

Light temperature in different rooms

Living room

We usually spend a lot of time in the living room and use the space for various activities: relaxing, reading, watching TV, playing games or socializing. Therefore, the right lighting in the living room is particularly important. The colour temperature plays a decisive role in creating the desired atmosphere and influencing our well-being.

Warm white light is great for creating a cosy and relaxed atmosphere in the living room. It fits particularly well in the evening hours, when you want to end the day comfortably.

Neutral white light has a more objective and sober effect. It is well suited for areas in the living room where you are a little more active, e.g. when reading or playing.

In order to achieve the optimal lighting in the living room, it is advisable to combine different light sources with different colour temperatures. In this way, you can create the right light for every situation and mood. Here are some tips for lighting in the living room:

• For basic lighting, use warm white light to create a cosy atmosphere.
• Use additional lights with neutral white light to illuminate certain areas, such as the reading area, in a more targeted manner.
• Use dimmable lights to adjust the light intensity and mood to suit the situation.
• Make sure that the lighting in the living room is evenly distributed to avoid shadowing.

With the right combination of different light sources and colour temperatures, you can transform your living room into a place of relaxation and well-being.

Bedroom

In the bedroom, relaxation and recreation are in the foreground. The right lighting makes a significant contribution to ensuring that we fall asleep well in the evening and wake up refreshed in the morning. The colour temperature of the light plays a decisive role in this.

Warm white light is the ideal choice for the bedroom. It creates a cosy and relaxing atmosphere that prepares the body for a night's rest. The warm light is similar to the light of a sunset and promotes the production of the sleep hormone melatonin.

Neutral white light is less recommended in the bedroom, as it has a more stimulating effect than warm white. However, if you want to read in the bedroom or do other activities that require a higher level of concentration, you can use lights with neutral white light. Daylight white light should be avoided in the bedroom. The bright, bluish light has an activating effect and inhibits melatonin production. It disrupts the natural sleep-wake rhythm and can lead to problems falling asleep.

Tips for lighting in the bedroom:

• For general lighting in the bedroom, use warm white light. Ceiling lights or wall lights with warm white LED lamps create a pleasant atmosphere.
• Install reading lamps with warm white light on both sides of the bed. So you can read something before going to bed without disturbing your partner.
• Choose dimmable luminaires to adjust the light intensity to suit the situation. This allows you to gradually reduce the lighting as you prepare for the night.
• A night light with very low brightness and warm white light can be helpful to orient yourself in the bedroom at night without disturbing sleep.

Kitchen

Good light is especially important in the kitchen, as we do precise work here, such as cutting, cooking and baking. The right colour temperature not only contributes to functionality, but also to the atmosphere in the kitchen.

Neutral white light is the ideal choice for basic lighting in the kitchen. It is similar to daylight and provides clear and bright illumination of the room. Neutral white light makes it possible to see colors and details well, which is especially important when cooking and preparing food. It also has an activating effect and promotes concentration, which can be an advantage for complex cooking tasks.

Warm white light works well for accent lighting in the kitchen. It creates a cozy and inviting atmosphere and makes the room feel warmer and cozy. Warm white light can be used above the dining table or in seating areas in the kitchen, for example, to create a relaxed atmosphere for shared meals.

Daylight white light is usually too cool for general lighting in the kitchen and has a sterile effect. However, it can be used selectively to additionally illuminate certain work areas, such as the worktop.

Tips for lighting in the kitchen:

• Use neutral white light for general lighting in the kitchen. Ceiling lights or recessed spotlights with neutral white LED lamps ensure good and even illumination of the room.
• Additionally, illuminate the worktop with LED lights or strips to ensure optimal illumination when cooking and preparing food. Daylight white light can also be used here.
• Set accents with warm white light to create a cozy atmosphere. For example, illuminate the dining table or seating areas with warm white LED lamps.
• Choose dimmable lights to adjust the light intensity to suit the situation. This allows you to reduce the lighting if you just want a cozy atmosphere in the kitchen in the evening.
• Combine different light sources with each other to create varied and functional lighting in the kitchen.

Bathroom

In the bathroom, we need lighting that supports us in shaving, applying make-up and styling on the one hand and creates a relaxed atmosphere for a soothing bath on the other.

Neutral white light is the ideal choice for basic lighting in the bathroom. It allows for good colour rendering, which is especially important when applying makeup. Neutral white light also has an activating effect and helps us wake up quickly in the morning. It is great for illuminating the mirror area and ensures that we can clearly see our facial features.

Warm white light creates a relaxing and soothing atmosphere in the bathroom. It is reminiscent of candlelight or the light of a sunset and invites you to relax. Warm white light is therefore particularly suitable for lighting the bathtub or a whirlpool to create a relaxing atmosphere for a soothing bath.

Daylight white light is often too cool for general lighting in the bathroom and has a sterile effect. However, it can be used selectively to provide additional illumination to certain areas, such as the shower area.

Tips for lighting in the bathroom:

• Combine different colour temperatures: Use neutral white light for the basic lighting and the mirror area and set accents with warm white light in the bath or shower area.
• Make sure that the mirror is illuminated evenly and glare-free to avoid shadows on the face. Mirror lights with integrated LEDs or wall lights that are attached to both sides of the mirror are suitable for this purpose.
• Choose dimmable luminaires to adjust the light intensity to suit the situation. This allows you to reduce the lighting in the evening and create a relaxing atmosphere for a soothing bath.
• Combine different light sources with each other to create varied and functional lighting in the bathroom. Ceiling lights, wall lights, mirror lights and recessed spotlights allow for a variety of lighting designs.

Study/Office

In the study or office, optimal lighting is particularly important in order to be able to work in a concentrated and efficient manner. The colour temperature of the light has a considerable influence on our performance and well-being.

Daylight white light is the ideal choice for the study as it promotes concentration and attention. It supports the production of the hormone cortisol, which makes us awake and efficient. Daylight white light is ideal as basic lighting in the study and can be supplemented by additional desk lights with the same colour temperature.

Neutral white light is a good alternative if daylight white is perceived as too glaring. It is still bright enough to ensure good illumination of the workplace and at the same time looks a little less strain on the eyes.

Warm white light is less recommended in the study, as it has a relaxing effect and can impair concentration.

Tips for lighting in the study:

• Make sure that there is sufficient brightness in the workplace to protect the eyes and prevent signs of fatigue.
• Position the luminaires so that the workplace is well lit and there are no distracting shadows.
• Use anti-glare lights to avoid reflections on the screen and protect the eyes.
• The optimal light temperature varies from person to person. Experiment with different color temperatures to find out which light is best for you to focus on.

The Colour Rendering Index (CRI)

The Colour Rendering Index, also known as the Colour Rendering Index or CRI value, is a measure of how naturally colours appear under a given light source. It indicates how well a light source reproduces the colours of an object compared to a reference light source, such as sunlight. The higher the CRI value, the better the colour rendering and the more natural the colours look. A high CRI value is important in many areas of life because it contributes to a better perception of colours and details. Modern light sources such as LEDs enable very good colour rendering and can even reach values of up to 100, which corresponds to perfect colour rendering. Values between 70 and 98 are considered very good. Good colour rendering is important, for example, when applying make-up, choosing clothes or looking at works of art. But precise colour reproduction is also essential in the working world, e.g. in the printing industry or in graphic design. Therefore, choose bulbs with a high colour rendering index to ensure the most natural colour perception possible.

Conclusion: The right light temperature for every need

Light colours play a crucial role in shaping the atmosphere and functionality of spaces. The colour temperature of the light influences our mood, our concentration and our well-being. By combining different light colours and light types in one room, you can create a versatile and stimulating lighting landscape that meets both functional and aesthetic requirements.

At Globo Lighting you will find an extensive range of different lamps and lights with different colour temperatures. Many lamps are dimmable and allow you to change the colour temperature. These include, above all, our RGB luminaires and our LEDs.

Glossary: Important terms related to light temperature

Below is a list of the most important terms for light colour with brief explanations:

• Colour temperature: Colour temperature describes the color impression of a light source and is measured in Kelvin (K). It ranges from warm white light with a low Kelvin value (e.g. 2700K) to daylight white light with a high Kelvin value (e.g. 6500K).
• Warm white light: Light with a low Kelvin value (about 2000-3000K) creates a cozy, warm atmosphere and resembles the light of an incandescent bulb. It is particularly suitable for living rooms, bedrooms and areas where relaxation is desired.
• Neutral white light: Light with an average Kelvin value (approx. 3100-4500K) has a neutral and objective effect. It works well for workspaces, kitchens, and bathrooms because it reproduces colours and details well.
• Cool white and daylight white light: Light with a high Kelvin value (from 4600K) is similar to natural daylight and has an activating and concentration-promoting effect. It is well suited for offices, offices and areas where high attention is required.
• Kelvin (K): The unit in which the colour temperature is measured. It was named after the British physicist William Thomson, also known as Lord Kelvin.
• Color rendering index (CRI): The colour rendering index indicates how natural colours appear under a given light source compared to a reference light source (e.g., sunlight). A high CRI value (e.g. above 80) means good colour rendering.
• Lumen (lm): The unit in which the light output or brightness of a light source is measured. The higher the lumen value, the brighter the light source.