Residential Architecture and Landscape Design

Color Temperature of LED Lights

Added on by keith messick.

LED (Light Emitting Diode) lights, while they were invented quite some time ago, have now become accessible, applicable, and affordable to meet all lighting needs.  LED lights are now found in every configuration to replace your existing incandescent or fluorescent lights.

Chart of Bulb Types - LEDs can replace almost all bulb types

While LEDs may be manufactured in similar fashion, the quality of the light produced by each bulb varies widely.  All light is not created equal.  There are three key properties to LEDs that must be considered before purchasing.  Manufacturers are required to supply a descriptive panel on the package that lists these properties: Brightness, Light Appearance (Color Temperature), and Energy Used (Wattage).  You should also note, found elsewhere on the box, if the bulb is dimmable.  All LEDs are not universally dimmable.  While some are, others are not.  And the quality of how the light dims varies.  Some will dim smoothly, while others will dim in a step-wise function.

Brightness:  The brightness refers to how much light will be produced by the bulb.  More lumens is brighter (more light).

Light Appearance: The light appearance is often referred to as color temperature.  It is given in degrees kelvin (k).  Higher temperatures are cooler, towards the blue spectrum, and lower temperatures are warmer, towards the red spectrum.

Energy Used: The energy used refers to the amount of power the bulb consumes while it is turned on.  The higher the number, the more the bulb will cost to use.  

The two most important properties of these bulbs are the brightness and color.  

In general, the higher the wattage, the more light (more lumens) the bulb will produce.  Note that higher wattage does not directly translate to a brighter bulb.  Some bulbs are more efficient than others, resulting in a brighter light for a given wattage.

Manufacturers tend to sell these bulbs by wattage comparisons.  The package will list the bulb as a 75 watt "equivalent" (or "replacement"), referring to the light that is produced from an incandescent bulb.  While that is a good place to start, it should not be the only piece of data used to select a bulb.  Also note that to compare the brightness of a bulb, the lumen output of one bulb must be compared to the lumen output of another.  You cannot use watts to compare brightness.

The bulbs, above, use the wording "replacement"  or "equivalent" to describe their brightness

Color temperature is the most significant attribute of a bulb.  The most common color temperatures are 2700k, 3000k, 4000k, and 5000k.  There are two familiar reference points from which to judge the color of light: the incandescent bulb and the sun.  An incandescent bulb is about 2700k, amber in color, and often referred to as warm.  The sun is about 5000k, very bright white, and is much less warm (cooler in color).  Reflected light from the sun is nice to have in the house during the daylight hours.  Most people, however, prefer a light color in the 2700k range for use indoors and consider light in the 5000k range too harsh.

Before selecting a bulb, perform a physical test comparison.  Purchase a sample of the bulb or bulbs under consideration.  Place the LED bulb in a fixture next to a reference incandescent bulb and compare (look at) the differences in the brightness and color of the light.  When you do a side by side comparison of several LEDs next to the reference incandescent, you will be amazed at the subtle differences between the bulbs.  It is best to compare the bulbs in question all at one time.

Do not assume that bulbs from the same manufacturer will have the same color output.  The color of light can vary between bulbs even from the same manufacturer.  The lights must by physically tested (compared).

Today, LEDs are very good at reproducing the equivalent brightness and color of the incandescent bulb.  However, LEDs are typically brighter than an incandescent and the color will be slightly off.  Incandescent lights are amber in color and are typically about 2700k (in color).  In isolation, LEDs look pretty good.  However, the color of the LEDs tends to be just slightly green or slightly red, in comparison.  (Do the comparison at night with no other lights on.)  

Compare LED bulbs not only against the incandescent reference, but also against each other.  The goal is to select the LED bulb that best replicates the incandescent bulb.  When developing a lighting plan for a room, the subtle differences observed between LED bulbs becomes critical.  When bulbs are used next to each other, as in the physical comparison described above, the differences in the color of the light will be more pronounced.   The easiest way to avoid these differences is to use one type of bulb exclusively.  However, this is often not practical.  Again, a physical test comparison will reveal which bulbs are color compatible.

In the end, select the LED(s)  that you think best represents the color you prefer.