Color Temperature

One of the things that bugs me the most when I’m out visiting new customers or potential clients is when lamps in the fixures are a different color.  Usually this happens because a maintenance person goes to a local big box store and picks up whichever lamp is the first he/she finds that is the same size.  I think that it looks a bit tacky.  But most times customers don’t know the difference and don’t know what to look for when buying lamps.  Here’s a quick lesson on what to ask for.

First you need to know if you have T12 or T8 lamps in your fixtures.  (I’m talking about the 4 foot bulbs that are in 95% of office fixtures)  The T12’s are fat, and the T8’s are skinny.  Next you’ll need to know the color.  On the bulb it will say something to the effect of “Warm White” or “Cool White” on a T12, or 735 – 741 – 750 on a T8 lamp.  The difference is in the look of the lamp.  A Warm White color, or a 2700 kelvin to 3500 kelvin temperature looks a lot like a standard everyday 60watt light bulb that everyone has in their homes.  The “cool white” color or 4100 kelvin temerature has a colder look to it.  All this means is that there is more blue in the color.  Then there is a 5000 kelvin lamp that is representative of a “daylight” color.  See this picture below.  It goes from Warm White to Cool White, to Daylight.

Correlated Color Temperature Explained

 As you can see the warmer color on the left is a lot different than the Daylight color on the right.  And putting them together in a fixture will cause an eyesore. 

Why would you use one color over another?

Well, many people find the warm color to be comforting in a residential enviornment.  It darkens tan colors and gives a general warm feel to the room.  The cool white color is generally found all over offices and other commercial buildings and can have an “institution”, cold-like feeling to it.  But for the most part it does a nice job of ligthing office and warehouse spaces.  I’ve had customers move to a daylight lamp because it gets past the institution feeling and gives workers a sense of being outside.  I’ve heard customers say that employees have less problems with headaches while using the 5000k lamp. 

For the most part the color used in your space is a personal preference.  But PLEASE!!! standardize and stick with one color.  We here at Adventure Lighting combat this with our customers by keeping a history of what was bought in the past.  If you bought a case of Cool White lamps 2 years ago, we’ll make sure you get the same color lamp today.

Jack Huff, along with his son Brian and wife Sue, owns and manages Adventure Lighting in Des Moines, Iowa. For more information, go to

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