The Edison Lamp: Better To Burn Out, Than Fade Away?
Thomas Edison was a great inventor and the father of the electric light bulb. In fact, the incandescent lamp used today is virtually unchanged from his original design. His genius gave us a light source that opened up the 20th century for our well-lit, modern caves. It’s been fun, but now it’s done.
In December of 2008, former president George W. Bush signed into law the Energy Independence and Security Act of 2008, (HR-6). In section 321, this definitive energy regulation declares that other than a few exceptions, the general purpose incandescent lamp is being extinguished. The phase-out begins in the next 3 years, with only tougher regulations foreseen in the future. The European Union begins in September of this year. Oh, there are certainly light sources that will take its place. We have LEDs, O-LEDs, fluorescents, HIDs, cathodes, and induction lamps to name a few. Each of the replacement light sources has its own strong points. Some have a long life, some boast reduce heat or give more light per what. But can they duplicate what Mr. Edison and his tungsten wrapped threads accomplished in the late 1800s? The answer is NO. Here’s why.
Through the past, oh say 200 million years, life on planet earth has had the luxury of seeing with the complements of our sun. The sun produces generates a good mixture of colors that is delivered to us in what we know as ‘white light’. It establishes for all of us a common platform to see and agree on what is Red or what is Blue and so forth (never mind the philosophical questions of the existence of either). This is because you don’t actually see an object, but only the light that is reflected from it. It absorbes some of it and reflects back the ‘color’. Since we (as a species) grew up under the sun, all that we see under it is true color–or at least a consistant electromagnetic wavelength reflected from objects into our eyes.Yet when you bring the same object indoors under a non-incandescent light source, these items do not receive the 100% of colors that they receive outdoors. They only receive what we can technologically give them with our science. This property of a lamp is called the color rendering index or CRI. The sun has a CRI value of 100, of course.
Granted, our science will always get better and I have no doubt that there are future Edison’s that will make it so. Yet, right now we just don’t have the know-how. What Thomas Edison happened upon was a lamp that could be economically produced with low cost supplies that has a CRI of 100-or equal to the sun in the sky. All other lamps not based in that technology have CRI ratings below this. Some have a high 92, while others can be found in the low 70s.
Still, the sad time has come for quantity to win out over the quality. Since we are all on this planet together, it’s time we took responsibility for our gluttonous energy ways. The problem with our lighting is that in most cases we just don’t get enough quality for what we have to pay for in energy. When gauging a lamp’s energy appeal, we use the term efficacy. Efficacy is the ratio between the total visible light and the total amount of input power it consumes. Here’s a chart that demonstrates where Edison’s lamp falls into the most common manufactured light sources:
| Source Type | Lamp Source |
Efficacy Rating |
| Combustion | Candle |
.03 |
| Gas mantle |
2 |
|
| Incandescent | 40w tungsten |
12.6 |
| 100w tungsten |
17.5 |
|
| 100w tungsten glass halogen |
20.7 |
|
| Fluorescent | 9-26w compact fluorescent |
60-72 |
| T12 tube with magnetic ballast |
60 |
|
| T5 tube with electronic ballast |
70-100 |
|
| T8 tube with electronic ballast |
80-100 |
|
| LEDs | White LED |
up to100 |
| HID | Metal halide |
65-115 |
| High pressure sodium |
150 |
|
| Low pressure sodium |
183-200 |
|
| 1400w sulfur lamps |
100 |
You can see that short of an open flame, the incandescent lamp has the poorest efficacy in our lighting family. But there are other factors that make a lamp source acceptable for incandescent replacement. Here are a few:
Color Temperature: This is the feeling of warm and cool that we get from a lamp source. It’s reflected in Kelvin degrees and opposite to what you’d think. A warm lamp actually carries a lower Kelvin temperature than a cooler lamp, which burn higher. Make sense? No? Try this then: a standard incandescent lamp burns at around 2800-3300 degrees Kelvin. While a cooler fluorescent tube burns at 4100-5500k. Daylight is at 6500k.
Disposal: Some lamps, such as HID or fluorescents have small amounts of mercury. We all know that mercury has a nasty little habit of finding its way into our food supply. Therefore, mercury=bad. No mercury=good. There are mandatory recycling initiatives for standard fluorescent tubes that keep the mercury out of our kids’ DNA. Yet, in recent times the lamp manufacturers and government authorities hatched an ingenious plan to lower the mercury content so that we could throw them away. This still means mercury is getting into our environment. Wouldn’t it make sense to quadruple the mercury content and make sure that everyone recycles? Show them: recycle anyway.
Price: Alternatives for the Edison lamp aren’t cheap. However, by choosing the right lamp, such as a good fluorescent or LED source, you can actually plot a Return of Investment (ROI) or even make money once it is paid off. This is easy to accomplish due to the very appetizing lamp lives that they have.
It’s no doubt that once we start to push the incandescent bulb out of distribution, the consumer will need a little more savvy in their lamp purchases. With proper understanding of the replacement technologies at our disposal, we can mimic the properties of the Edison lamp. But as far as duplication, we’ll need to settle for around 80-90% for a while at least.
Thanks for reading.
John Maclay
Interesting article, thanks.
I’m a bit confused though. Your standard incandescent light bulb is nowhere near full spectrum. The near full spectrum bulb I have is, I believe, fluorescent and I’ve only ever seen them in this form.
Alissa, you ask a powerful question and deserve sufficient explanation. Without getting to mired in the physics and science of light delivery and color perception…here goes.
The terms to remember are:
1. Correlated Color Temperatures (CCT): a number expressed in degrees on the Kelvin scale. Warmer colors being a lower temperature and cooler colors being higher.
2. Spectral Power Distribution (SPD): the levels of each color wavelength in a light source. It ranges from the reds to the blues on the ROY G. BIV rainbow scale. The mixture of these determines the CCT.
3. Color Rendering Index, (CRI): a number express from 0 to 100 with the obvious scale values for showing the accuracy of color perception at a given CCT.
CCT and SPD work together to influence your eye’s perception of an object’s flavor. The CCT & CRI are related in that the CRI measurements for two light sources can only be compared if they have the same CCT. For example, the sun has a CRI of 100, yet a CCT of a cool 5800K. A 60w incandescent lamp also has a CRI-100, but is a warm 2800K. The color is rendered at an index of100 for both of them–it’s just the flavor that has changed.
Our interactions with the sun through the evolutionary process endowed our eyes with keenness at a higher blue color temperature. Even when our troglodyte ancestors hunted at night, the moon gave them a CCT of around 4100k. We are biologically configured to see clearer (discern colors and contrast) at these higher color temperatures, yet we find more comfort in a 3000k environment. Maybe we subliminally equate a warmer CCT with chewing on fresh mastodon around a nighttime cave fire.
Now, on to full spectrums. Full spectrum is a term used to imply a smooth spectral electromagnetic distribution. They are usually fluorescent, but are available in incandescent too. Their characteristics include:
1. Marketing campaigns that tout a departure from artificial light.
2. Having a CCT of 5000+, bringing the clarity of natural daylight.
3. The promises of better color, productivity, plant growth, higher profits and tooth decay prevention.
4. Emit UV radiation.
5. Have a high CRI, usually above 90.
Full spectrum lamps are tuned more toward our eye’s sensitivities; yet do not render colors with the accuracy of the sun or an incandescent lamp at their native CCT. Their CRI is below 100, but high enough not to make much of a difference. Full spectrum sources do, however, bring a broader SPD to your tasks; therefore, a viewer may experience better discernment between colors.
Yet, according to the Lighting Research Center, there appears to be little evidence to support most of full spectrum marketing claims. It appears that full-spectrum light sources will not provide better visual performance than similar sources under most circumstances. The UV radiation is also something to think about since prolonged exposure may damage artwork pigments. Furthermore, the jury is still out on whether the promised psychological benefit of ‘well-being’ is from the actual SPD or the clever marketing approach dubbing them “natural” lighting.
In short, FSL lamps are good, but you may be able to save money by dialing in your CCT and CRI with a standard lamp to what you require of it.
Here’s a link to the Lighting Research Center’s work on full spectrum lamps: http://www.lrc.rpi.edu/programs/nlpip/lightingAnswers/fullspectrum/lightSources.asp
Another link to an SPD chart of two lamps.
http://en.wikipedia.org/wiki/File:SPD.png