What is Color Temperature, Anyway?

If you’ve purchased an LED or CFL light bulb recently, you’ve probably heard of color temperature. And likewise, if you’ve talked to an older family member recently about their lightbulbs (and honestly, who hasn’t?), then you’ve probably heard about it as well, albeit in stronger language.

So what is color temperature, anyway? Basically, it describes the color of your white light. That may seem counterintuitive; white light is, after all, white. It shouldn’t really have a color. But within the blanket category of “white”, there’s a lot of variation. Think of the cold, white light you might see in a hospital or 1980s office park. Now think of the warm, inviting light from an old incandescent bulb in your family room.

What’s the difference? Color temperature. That sterile, industrial light probably has a high color temperature. The warm, inviting light has a lower one. Old incandescent bulbs were color temperature savants (at least according to most peoples’ tastes), whereas CFL bulbs (at least the older generation ones) were notorious for being in the ugly, cold part of the spectrum. Thus the rant from Grandpa, if he was forced to switch.

Luckily, newer bulbs give you a lot of control over color temperature, whether they’re LEDs or CFLs. So how do you choose? Color temperature is measured on a scale that you’ve probably learned and then forgotten: absolute temperature, measured in Kelvin.

The scale starts in the lower 2,000Ks, with things like a match flame and the “warmest” of incandescents. On the higher end, you get light sources like the sun, which clocks in at a cold, blue 5,800 K (and here I always thought it was yellowish…live and learn). That pleasant, incandescent light you grew up with? It’s probably around 2,700K. The soul-sucking florescent lighting your cubicle? 4000k.

This graphic, and the one above, shamelessly lifted from Wikipedia.This graphic, and the one above, shamelessly lifted from Wikipedia.

This graphic, and the one above, shamelessly lifted from Wikipedia.

When you’re buying bulbs, then, think about the kind of lighting you like. If you’re nostalgic for the glory days of old fashioned bulbs, go for LEDs or CFLs in the 2,000K range. If you prefer a bluer, “daylight” kind of light, go for the higher end of the color temperature scale. Make sure to think, too, about the kind of space you’re lighting. Higher color temperature bulbs are great for a foyer or perhaps even the kitchen or dining room, but a stark, unforgiving daylight glow probably isn’t right for the den or bedroom.

Of course, nowadays good CFLs and LED bulbs can last 10-25 years, so a poor color temperature choice could haunt you for a long time. For the chronically indecisive, Phillips Hue offers a neat (but expensive) alternative. Their Hue bulbs allow you to change the color temperature from a smartphone app, going instantly from a nice, warm light for relaxing to a stark, bluish white light for reading. Their app even has cute names for each setting–low color temperature settings have names like “Relax”, and high settings are “Refresh” and “Concentrate.”

Again, the most important thing about color temperature is that it’s a personal choice. Make sure to try a few different options before committing to a particular color temperature. And if you still can’t decide, just go with 2,700K. Grandpa will thank you.

G7 Power: The Best Light Bulbs

Recently, I decided to finally bite the bullet and swap out the old incandescent lightbulbs in my home. Before you stop reading in disgust or leave nasty comments about the fact that I still have incandescents in 2014, let me take a step back and say that I swapped out the vast majority of my bulbs for CFLs a long while ago. I like the soft-white ones from Phillips; they draw about 22 watts for a 100 watt equivalent brightness, they produce a nice quality of light, and they’re cheap.

CFLs have their downsides, though. They’re (usually) not dimmable. Even with good ones, the light has that vague office building-esque character to it. They’re big, and can be hard to squeeze into compact fixtures. And if you break one by trying to force it into one of those fixtures (as I did recently), you have to go into full hazmat mode and evacuate the house to avoid mercury poisoning.

Still, I had already gone CFL for the majority of my lights. The ones which remained incandescent were the problem children: a three-bulb dimmable hanging light in my dining room and track lighting in my kitchen. When I set up Bidgely to monitor my home energy use, it quickly became clear that these bulbs were costing me. Leaving them all burning (as I tend to do) was consuming 700 watts, or about 25 cents per hour at California energy rates. Do that for 4 hours a day and you’re paying $30 per month to light two rooms.

Given the potential savings, I decided to make a switch. I would go LED.

LED lights have come a long, long way in the last several years. They combine many of the advantages of incandescents (good light quality, instant warmup, easy dimming) with the advantages of CFLS (low energy use, long life). The biggest issues with LEDs are normally price and brightness. I have a couple Hue bulbs from Phillips (more on these later) which are awesome for home automation, since you can control them from a smart phone, and they generate fantastic light. But they cost $60 per bulb, and even the basic Phillips LED bulbs hover around $15 for a decent brightness.


Enter G7 Power. I discovered G7 while doing a random Amazon search. They’re based in Reno, Nevada and were founded by an electrical engineer. They make all manner of LED bulbs, get stellar ratings on Amazon, and are even veteran-owned. And the best part? Their bulbs are cheap. You can get a 60w equivalent bulb for around $10, and they make a high color rendering index bulb (read: one which makes excellent quality light) for about $14. They even make weird bulbs, like the little GU10 bulbs for my track lights.

track light.jpgtrack light.jpg

Naturally, I was skeptical. Were these bulbs really going to make light of comparable quality to the more expensive Phillips ones? Would LED tracklighting even look right? I decided to order a couple bulbs to see.

Turns out, the G7 bulbs are great. The light quality is excellent. I opted for the high CRI bulbs, which have a color temperature of 3000K, and they add in just the right mix of sunlight-esque coolness without making the dining room look like a 1980s office park.

For those who like the color yellow, G7 power makes 2700k bulbs too, which will look much more like your traditional incandescent. The bulbs dim pretty nicely, too. My only complaint is very occasional flickering, probably when there’s a power surge through my dimmer.

dining room light.jpgdining room light.jpg

The best part, though, is the energy savings. Running all my track lighting and the hanging fixture, I’m drawing about 50 watts; a more than 10-fold decrease from my old bulbs. With just the track lighting running, I draw so little that Bidgely has trouble keeping track. My first electrical bill after making the switch was almost $30 lower.

So if you’re thinking of swapping out your incandescents for the best-in-class LEDs, use Phillips Hue. But if you don’t have $4k to drop on lightbulbs, take a look at G7 Power.