Kelvin (K) is a unit of measurement that’s used to describe the hue of a light source. The higher the Kelvin value, the bluer and colder the light is. Correspondingly, the lower the Kelvin value, the yellower and warmer the light is.
The scale of measuring Kelvin is based upon the principle that a black body radiator emits light in different colors in different temperatures. At 300 kelvins the body is black and emits only heat. At 800 kelvins the body is red, at 4000 kelvins the body is white and at 20 000 kelvins the body is blue. The color temperature of light fixtures usually varies from 2700K to 6000K.
The color temperature of lighting influences significantly the ambience, atmosphere and mood of the space.
Usually, an incandescent light bulb has a color temperature of about 2700K, which is a slightly warm white. Low Kelvin values are usually used in residential spaces, since white and yellowish light is considered cozy. A halogen bulb has a color temperature of approx. 3000K.
In public and commercial spaces, mainly cold and blueish white light is preferred. That is, light fixtures with a high Kelvin value.
There is more variation in the color temperatures of LEDs and energy saving lamps. For energy saving lamps, the hue ranges from neutral white to warm white. LEDs are available in any color. A lamp with a color temperature of over 5000K is referred to as a daylight lamp.
In addition to the color temperature, you should also consider the luminous intensity LUX (lx) required by the size and purpose of the space when designing lighting. It’s also essential that the color rendering index (CRI) of the light fixture is at least Ra>80 in order to reproduce the colors of the illuminated objects naturally.