CCT or Correlated Color Temperature is used to determine the color of light sources that are close to white. They are measured in unit, Kelvin (K), and light sources are commercially available between 1800K and beyond 7000K. An 1800K source of light is very warm, or orange / amber. They are often used in hospitality environments where a very subdued and intimate feel is desired. At the other end of the spectrum, a 6500K source is very cool or blue. They are often used in settings such as a hospital or school where visual acuity is important. In the middle, a 4000K font looks very white.

Incandescent sources are in the hottest part of the spectrum and have a slightly yellow hue. These usually fall around 2700K. Halogens are considered still hot, but have a slightly less warm CCT closer to 3000K. These fountains are most common in homes, shops, hospitality, and museum settings. Most consider the hottest ranges of lighting to be the most comforting and calming. A unique aspect of incandescents and halogens is that as they dim, their color temperature decreases, turning from yellow to amber to orange. Often times, restaurants will dim their incandescent fountains way down at night, leaving only a warm orange glow radiating from the filament. Non-incandescent sources will normally be the same hue as they are dimmed. Fluorescent sources come in a wide variety of color temperatures. This is because without phosphors, fluorescents would only produce ultraviolet light that our eyes cannot detect. Different matches in different quantities produce different colors. Fluorescents have been used frequently in areas where lights are on consistently for a long period of time, as they are more efficient than incandescent ones. Office building, schools, and hospitals often use fluorescent lights. LEDs, too, are available in all color temperatures, as they also use phosphors to alter their color. There are replica carbon filament lamps that are as low as 1800K, fluorescent replacements that are as cool as 6500K, and many sources in many K’s in between. LEDs are rapidly replacing all types of lighting, as they are extremely efficient, have a very long lifespan, and can produce a great deal of light from a relatively small package. You can find LED lamps almost everywhere these days.