Kelvinated

Not too long ago, my friend Keith dropped over to my desk at work and asked me, "Have you tried to buy light bulbs lately?" I responded that I had, and that the array of available options was dizzying. Keith was trying to replace a five-plus year old bulb in his house with the equivalent, but nothing seemed to be a truly good match. Really, you say? Oh, yes. Light bulb buying is a rather complicated endeavor these days.

As you've probably noticed if you've tried to buy replacement bulbs lately (and who hasn't?), the plain old incandescent bulb is essentially a thing of the past. Government regulations throughout the world have prohibited the manufacture or sale of them unless they are sufficiently energy efficient, and this is probably a good thing. For years, people have used halogen or xenon alternatives for task lighting in areas such as kitchens and workshops, but in the last few years, LED (light-emitting diode) lighting has become the preferred technology. The light is pure, clean and extremely energy efficient. There's only one problem with LED lighting, and that's the Kelvin scale for color temperature. Many people who are otherwise brilliant, conscientious and informed do not seem to understand the Kelvin scale and its relation to everyday lighting options.

The Kelvin scale is a absolute numeric index of temperature, and as it pertains to lighting, it serves as a color index as well. (I've included a helpful diagram with this post.) Lower Kelvin values tend to be warmer, while higher values more closely simulate daylight. As the Kelvin value increases, the light becomes more bluish. For example, soft white 100 watt home lighting is generally around 2700K, while surgery suites often utilize lighting in the 5000K or "daylight" range. The kind of lighting selected is typically based on the need: if you are looking to generate a warm, inviting feeling for your living room, select the lower temperatures; if, on the other hand, you need to simulate daylight and reflect most of the light impinging on an object back to your eyes for detailed desk or table work, select higher temperatures.

Selecting the "wrong" color temperature can have unpleasant consequences, particularly in outdoor lighting applications, where the human eye expects more gentle light. A quote from the Lightology website sums this up well:

Stay away from cooler color temperatures when lighting outdoor landscapes. The bluish tones from cooler temperatures can make environments appear sickly or unnatural, imparting a sense of uneasiness, and being on edge. Instead, opt for lighting with a very warm color temperature: 2700K LED is ideal, and 3000K is okay, too. The 2700K temperature offers a very soothing and natural tone that mimics the warm, comforting glow of a campfire. As such, it is ideal for creating relaxing, comfortable outdoor environments.

I always feel sorry for people who have selected higher Kelvin lighting, because I'm guessing that they are probably trying to do the right thing by being energy efficient, but that they haven't paid much attention to the details. Most of us consider "daylight" to be a good thing, but when it comes to outdoor environments, installation of high Kelvin options imparts a rather post-apocalyptic feeling to one's surroundings. I know that in my case, at least, I would like for my front yard to appear inviting, so that when you come to visit, you feel like you're going to be served a chilled martini instead of having your appendix removed.

That being said, there are definite benefits to LED lighting in some situations. Recently, all our incandescent choir loft lights, which sputtered and failed in a most inappropriately sacrilegious way, were replaced by LED's. The result was that we could now see our music evenly lighted without the fear that the lights would fail or that we would be spontaneously incinerated by the heat from the old incandescent bulbs. Two years ago, I saw a soprano's music almost catch fire. OK, I made that last part up, but you know what I mean.

The whole thing is fascinating in a way, and the technology available these days is seemingly limitless. So go out there when you have a chance and spend some time in the lighting aisle of your local Home Depot or Lowe's. You'll be amazed at the options available, but keep this Kelvin thing in mind, or you just may end up reawakening the spirit of George Orwell.