Light color
The term ‘light color’ is defined in DIN 5033-1 as “the color of a self-luminous object” and serves to characterize light sources.
Color Temperature
The most common quantitative description of the color impression is based on color temperature, measured in Kelvin (K). The reference point is the spectrum of an idealized thermal radiation source (also known asPlanckian radiator, black body) which depends solely on temperature: At lower temperatures, light appears reddish, transitioning through orange and yellow to white, and finally to blue as the temperature increases.
Today only a few light sources on the market produce light through heating components, making a purely temperature-based description less applicable. Instead, the color location of the light color is determined, compared with the color locations of the Planckian radiator, and assigned to the nearest correlated color temperature (CCT)).
The representation of colors within the visible spectral range is mapped in the CIE-XYZ color space. Each color can be mathematically defined and expressed by coordinates. Along the curved black line (Black-Body curve), the color locations of the Planckian radiator are displayed.
White light is divided into three groups:
- Warm white (below 3000 K)
- Neutral white (3100-4500 K)
- Daylight white or cool white (over 4500 K)
However, these text labels may vary depending on the manufacturer.
For coloured light, the spectrum deviates so significantly from the Planckian radiator that a classification by correlated color temperature is not meaningful. Instead, characterization is color location.
Physiological / Psychological Effects:
The psychological and physiological effects of light color are part of a more complex framework and remain the subject of numerous studies. However, two everyday examples illustrate their impact:
Light with a higher color temperature contains more blue wavelengths, which suppress melatonin production enhancing alertnessand concentration. Simultaneously, the perceived ambient temperature decreases. This not only contributes to productivity but also opens up possibilities for more energy-efficient building usage. Since the influence of light color on temperature perception is most noticeable over shorter periods, it is particularly useful in transitional spaces. Accordingly, warmer light color creates a cozier, more inviting atmosphere, making it ideal for relaxation areas where comfort is a priority.
