What is the colour temperature of light?

Find out: What does lighting 'colour temperature' mean - How to specify lighting colour temperature for workplaces?

The below guide helps you to understand the definition of lighting colour temperature and why it is important in commercial & industrial lighting installations including factory lighting & warehouse lighting.

Lighting Colour Temperature Guide

Lighting Colour Temperature

In technical specifications for lighting and light fittings you will often see the term 'colour temperature' - but what is this? and what is the correct colour temperature you need for different commercial & industrial application?

Colour temperature - the ranges

Lighting colour temperature is measured in Kelvin (K) - artificial light is typically found in the range between 2700K and 6500K - with the light appearing cooler/bluer as the measured 'K' level is increased

The colour temperature is a measure of the colour appearance of a light source ranging from 'warm' light (e.g. - low and high pressure sodium lamps) through to 'cool' light (from metal halide lamps).

The effect of lighting colour on humans

The ranges of light colour have different effects on sleep cycle, productivity, and mood. Warm Light is relaxing which helps people to calm down and prepare for sleep. Cool White and Daylight contain blue spectra which helps people be wakeful, productive, attentive, and improves moods.

Circadian lighting

The natural colour temperatures observed over the course of a day produced by the sun vary from warm to cool. The early and late sunlight is low on the colour temperatures scale emitting a warm orange glow (2000K). The sunlight at midday is a cool blue colour temperature (10000K).

The right colour temperature of light for a workplace

Choosing a lamp with the right colour qualities is important in environments - particularly in large industrial buildings such as a factory or warehouse where lighting levels are crucial for maintaining good health and safety practices and keeping staff at maximum efficiency.

Here are some examples of appropriate colour temperatures for environments - a brief discussion follows:

EnvironmentTypical ColourEffect
Home, Living Room, Hotel, Restaurants2700K-3500KWarm glow, relaxation, cosy atmosphere
Offices, Shops, Retail3500-4500KBalanced White
Factory, Workshop, Warehouse4500K-6000KBright White - Precise, Vibrant, Crisp
Specialist environmentsover 6000KCool White, Blue-tinged

2700K-3500K - Warm Light

This light colour range gives a distinct warm glow that reminiscent of the sunset or a flame - it is more used at home and in relaxed commercial settings

3500K-4500K - Neutral White Light

This light colour range allows people to focus and remain alert for several hours when working in one space but still allows a degree of comfort

4500K-6000K - Bright White Light

This colour range is suitable in a workplace when clarity & precision is required - e.g. - specific working practices such as glass and metal works in a factory setting or environments such as healthcare

Over 6000K - Cool White

This light colour range can be common with some types of LED lighting which emit a more blue light to obtain a higher efficiency. It can be quite harsh to work under this colour light for many hours.

Reference diagram - Colour temperatures

The diagram illustrates this in more detail:

"Lighting colour temperature chart"
Lighting colour temperature chart

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