Colour Temperature – What It Is And How To Use It
Colour temperature affects every day of our lives but most of us are unaware it exists to help us identify and measure warm light, neutral light and cool light.
Having a knowledge of colour temperature has become increasingly important as the light bulbs and lighting we introduce to our homes and work spaces are available in a vast range of different tones.
This easy-to-understand expert guide will help you understand colour temperature, identify what’s right for you and the mood or feel you want to create.
What is colour temperature in light?
Colour temperature describes the tint of a particular light.
Think of it as a spectrum of colours from warm to cool that tells you whether a light source appears more yellowish-white (warm) or bluish-white (cool).
Imagine heating a piece of metal. As it gets hotter, it first glows a dull red, then orange, then yellow, and eventually white-hot, even bluish-white.
Colour temperature works similarly, although it's based on a theoretical "black body radiator" being heated. The temperature at which the radiator glows a particular colour is its colour temperature.
How do I know the colour of light?
The colour tint we see when we look at a light is measured in Kelvin.
Think of it as a scale that ranges from warm, yellowish light, to cool, bluish light.
While the Kelvin scale theoretically extends from zero to very high numbers, for practical lighting purposes, we're interested in a much smaller range, typically between 2,000K and 10,000K.
This corresponds with the colours of light we experience in our daily lives, from the warm glow of sunrise and sunset being around 2,000K to 6,500K at noon and sometimes 10,000K in the shade.
How do I use Kelvin?
Manufacturers of light bulbs and lights where bulbs are included will indicate the colour temperature in their product descriptions.
You can see here this Leo ST64 LED Bulb by Well Lit is described as having a colour temperature of 2,200K, which has a very warm and relaxing feel that’s perfect for helping us relax and unwind in the evening and perhaps getting ready to go to sleep.
Conversely, this Rim Pendant Lamp With Brass Styling - Cool Tones from Maytoni comes with a colour temperature of 4,000K, which has a much cooler feel and would be better for work spaces.
And this Kyoto Pendant Lamp In Black – Wide is set up to deliver a 3,000K tone of light, which is a warm white that’s ideal for all parts of the home.
What colour temperature light bulbs and lights can you buy?
The normal range of colour temperatures for light bulbs and lights which have bulbs supplied with them or built into the design are as follows:
2,000K-2,500K
This is a very warm, amber light, that’s ideal for creating a cosy, intimate atmosphere and is similar in colour to candlelight or the glow of a fire.
2,500K-3,000K
This is a warm white light that has a comfortable and inviting feel that similar to traditional incandescent bulbs.
It’s ideal for living rooms, bedrooms and dining rooms where you’re looking to relax.
3,000K
This is a warm white light that is the standard for residential use and can be used throughout the home.
4,000K
Considered to be a neutral or cool white, it’s a balanced and clean looking light that’s not too warm or cool and is ideal for kitchens, bathrooms and work spaces.
5,000K-6,500K
This is daylight white and mimics natural daylight, helping to give a bright and energetic feel and is good for use in offices, workshops and retail spaces.
FAQs
What is the colour temperature of tungsten?
Tungsten incandescent bulbs typically have a colour temperature of around 2,700-2,800K, producing a warm, yellowish light.
What is the colour temperature of LED lights?
LED lights are available in a wide range of colour temperatures, from very warm (2,000K) to very cool (6,500K or higher).
Which is brighter – 3,000K or 6,000K?
Colour temperature does not directly indicate brightness. Brightness is measured in lumens. However, cooler light (6,000K) often appears brighter to the human eye due to its higher blue light content.
Is 3,000 Kelvin warm or cool?
3,000 Kelvin is considered warm.
Is 4,000 Kelvin warm or cool?
4,000 Kelvin is considered neutral white, or a cool warm. It is in the middle range, and is neither strongly warm, nor strongly cool.
Can colour temperature affect our sleep patterns?
Yes, based on research published in the National Library of Medicine,the colour temperature of light can significantly impact our sleep patterns.
This is because our bodies have a natural 24-hour internal clock called the circadian rhythm, which regulates our sleep and awake cycles.
The colour temperature of light plays a key role in syncing this rhythm.
Exposure to cool, blue-toned light, suppresses production of the sleep hormone melatonin, making it harder to fall asleep.
Conversely, exposure to warm, yellow-toned light, consistent to what we might see at the end of the day may actually promote production of melatonin, helping us fall asleep.
Selecting your lighting to match what you’re doing in your office or home can help our levels of alertness.