Colour Temperatures and Kelvin Ratings in Lighting Explained
Colour Temperature Information
Colour temperature is generally defined by a Kelvin rating and is assigned the unit symbol K. Kelvin ratings are commonly found listed on low energy fluorescent lamps and LED lamps. Mains Voltage Halogen and Incandescent lamps generally don't carry colour temperature information but normally produce a white or warm white colour between 2700k and 3400k. Low voltage halogen lighting produces as slightly whiter light than it's mains voltage equivalent.
The international colour code is often used to denote the temperature of a lamp's light. This code is a three digit number. The first digit refers to the colour rendering index: if it is 8, then the CRI is between 80 and 90, if it is 9, it lies between 90 and 100. The next two numbers are the colour temperature (to the nearest hundred) divided by one hundred kelvins, thus if the temperature is 6500 K, the number is 65.
For lighting interiors, it is often important to take into account the colour temperature of the light fittings used. For example, a warmer (i.e., lower colour temperature) light is often used in areas of relaxation, while a cooler (higher colour temperature) light is used in work areas such as kitchens or offices.