It's cold and rainy.  There is a hurricane outside.  It's snowing!  It's 90 degrees outside....and I need to change a light bulb!  What color temperature bulb do I need? 

Well- um....
Honestly, color temperature and and outdoor temperature have nothing to do with each other.  So what's the point?

Actually, the color temperature of the bulb will have an effect on how you feel.  No, it can't refrigerate the air or replace your furnace, but it can have a direct effect on some of the activities you do in your home — cooking, art, office work, and other visual activities.  Have I got your attention?  Great!  Read on.

COLOR TEMPERATURE

Nowadays, we are all doing what we can to be more environmentally conscientious and energy efficient.  Fluorescent bulbs play a major role in our society.  Historically, there has been a bit of a negative connotation to the light these bulbs cast, and there's a reason for that.  Until recently, technology only allowed for one tip of the color temperature scale- the exact opposite of a traditional light bulb.  That is no longer true, and you can buy fluorescent bulbs in several temperatures.   The trick is, understanding how and what to choose.

Color temperature describes how "warm" (reddish) or "cool" (bluish) a tint of white appears. Color temperature is a reference number that "quantifies" the appearance of light. The terms "warm" and "cool" in lighting refer to subjective experiences, such as a warm flame or a cool winter sky.  

The COLOR TEMPERATURE of a light source is measured on the scientific Kelvin scale.  Imagine a piece of metal heated to a high temperature: it glows. At a high enough temperature, it will give off light (or incandesce) as when heating an iron at a forge or when sterilizing a needle by holding it over a flame. As the metal is heated, the higher the temperature, the bluer the light.

Think of the cooking gas flame in your kitchen oven. The inside is blue and the outside is orange/red. Which is actually hotter (higher degree temperature)? Blue. But when we think of a warm pleasing fire, we think of orange/red colors.

Blue is a color that makes us think of cold. Ice is bluish, for example.

"Cool light" is considered blue — a high color temperature. Warm light is more reddish, yet the color temperature is low. I know this sounds confusing, because it's the opposite of Fahrenheit's perception of warm and cool.   You'll see what I mean.

In lighting, we measure the cool/warm spectrum in Degrees Kelvin (K), and we can "see" between 2500 K to 7500 K.  That is the "visible light spectrum." We can measure light sources (including light bulbs) on this scale.  As mentioned above, "Cool" light is a high degrees Kelvin (7500K) and "warm" color would be about 2500K.

Don't let the "daylight" fool you. True, daylight comes in at 6500K. But that is not a desirable color for an indoor application because there is simply too much blue in 6500K. There are reasons why it's wonderful outside — it has to do with reflectance, spectral power distribution, color rendering index (not to get off on tangent — this is not the place for it), which is very different when the light source is indoors as opposed to outdoors. (Thus the need for a good lighting designer)....

To summarize, let me ask you a question:
If you buy a "full spectrum" Fluorescent bulb, what does that really mean?
Does it mean you are getting more bang for your buck? The whole kit and caboodle? Sunlight in a bottle?

NO.

It means you are buying a bulb that is 7500 degrees Kelvin. It's merely a very high color temperature.  And you got it — cool, blue, eerie and high contrast.

Great for reading, because of the high contrast between the black letters and the white page.  Sure to keep your eyes focused on that page.  But what if you need to see "true colors?" 

For example, let's say you were painting a portrait.  Paint it under a bulb  6500 K and above, and then take it into broad daylight.  Ever been in the twilight zone?

The face will likely be full of yellow and pink because you will have over-done those warmer colors, since you couldn't see them under the blue light.

And for all you gourmet cooks out there? (never mind, I don't want to go there)...

Oh and one other thing — that "full spectrum" also includes UV rays.  So to all you SAD (seasonal affective disorder) sufferers, beware.  Use the bulb but don't sit right in front of it.  I'm a Seattleite, we get a lot of SAD cases out here.  My own doctor uses a huge full spectrum lamp for a half hour each day in her office.  I like coffee instead (just kidding!)

"I HATE FLUORESCENT"
On the flip side, I hear this a lot. 
No need. Fluorescent used to not be available in lower color temperatures.  A standard regular non-energy efficient bulb is about 3500K.  You can get fluorescent bulbs with that color temperature nowadays.   Just check the box.

RECOMMENDATION
In summary, when lighting a home office, artist studio, or kitchen, you will want to create a comfortable environment that is free of harsh contrasts and distracting glare. You will need task lighting for art, food prep and serving, etc., and general lighting for the surrounding area. You may also want to include accent lighting for art on the wall. For an average sized room, two large ceiling fixtures, containing energy-efficient fluorescent tubes (3500K so they are a comfortable color temperature) will provide plenty of well-diffused general lighting, while eliminating shadows on the desk or work area. Place the fixtures overhead and to the right so the light comes over the shoulder.  Lighting placed in front of the desk will cause troublesome shadows.  Track lighting will illuminate artwork.  A desk lamp will provide task light. Pendants over an island and undercabinet lighting follow the same principal.  Position an office lamp so it does not reflect on your computer screen. The best type of lamp for this is a reading lamp with an opaque covering above, not a shade (as you would use on an end table). The best type of bulb to use is Halogen or Xenon, because they have the best color rendering index of all man-made light sources.

Well, there you have it. My little lighting sermon. Hope it was at least enlightening!

Questions? Contact me at rmizrahi@atgstores.com.  I would be happy to help you.

 

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