Kelvin Temperature in Lighting
Kelvin symbolized by K is a unit of measurement used to measure temperature. In lighting it refers to the color temperature of light sources. Temperatures of light sources and fixtures above 5000 K seen as bluish white is referred to as “cool” while yellowish to reddish light with a temperature below 3,000 K are called “warm”.
If light color temperatures had a scale then warm colors or yellows and reddish lights would be at the bottom. Candlelight for example is around 1,500 K; a 40 watt incandescent light bulb which is found in a lot of homes is around 2,700 K; the sun at high noon (pure white light) is around 5,000 K and fluorescent lights on the other hand have temperatures ranging from 2,700 – 6500 K.
Determining Kelvin temperature has very practical everyday uses. In homes, lots of people prefer using warmer colors like incandescent light bulbs because it projects a cozier and more relaxed atmosphere. The yellowish light also flatters human skin tone. In offices, bright fluorescent lighting is used to induce concentration and alertness. Light bulbs ranging in Kelvin temps from 5,000 to 6,500 are also the best for reading as it replicates daylight.
Surgery lighting systems used in operating rooms generally use high Kelvin temperature in order to produce an almost white light. These lighting systems typically use 4,000 to 5000 Kelvin light bulbs.
Jewelry stores also use lighting that has high kelvin rating. Bright lighting in jewelry store makes diamonds, gems, gold and silver gleam more, like they are in natural daylight. This makes the jewelry in the display cases seem more attractive to prospective buyers.
Many clothing retailers choose a lower kelvin light bulb at their stores. They want their stores to feel cozy and comfortable, an atmosphere where people will stay for awhile and spend money while there. They do not want it looking like an exam room with real bright white light.
Having the correct kelvin fluorescent lighting in your store/office/exam room can make an important difference to the atmosphere of the facility.