Not so long ago, most of the urban Indian homes were lit only with incandescent lamps. This love story got serious to the extent was that these light bulbs got cameos in most of the ghost stories, remember the oddly famous line “the lone light bulb hanging from the ceiling”. Jokes apart, the good news is that the story has changed and it has changed for the better. We have come a long way from the yellow hue of incandescent lamps to the modern age CFL and LED lights.
What’s more, along with the lighting situations, the power charges has also experienced changes. While the meter used to go into a spin due to high consumption of electricity, the situation is totally different for the CFL and LED lights.
Surely, many of us aware of the simple science behind the IL, so why not jump into the same chapter for the CFL and LED lamps as well?
Compact Fluorescent Light (CFL)
Compact fluorescent light or CFL is an energy efficient substitute of its incandescent cousin. The CFL light fixtures are molded in form of tubes that contain a blend of argon and a small amount of mercury vapor alongside fluorescent coating on the tubes.
A compact electric ballast is fitted in the lamp base. Electricity is passed through the glass tubes to excite the gas molecules which in turn produces ultraviolet light. This light upon reacting with the fluorescent coating produces the necessary white light.
As light output is directly proportional to the phosphor area, the higher wattage lamps are generally bigger with more turns of the phosphor coated glass tubes.
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Efficiency of CFLs
Although the initial buying cost of a CFL is more than an average light bulb, the energy consumption is around 70% lower.
The luminous efficacy of a typical CFL is 50–70 lumens per watt (lm/W) as against the 10–17 lm/W of its older cousin.
A higher luminous efficacy means that CFL almost uses far less power, almost one-seventh less. Also, in an ideal situation (good operating voltage and no manufacturing defects) the shelf life of a CFL lamp is much longer than an IL, though it can be cut short if it is switched on/off repeatedly.
So, if you control the impulse to turn off the light every 5 minutes (I know, old habits die hard), it can play a big role in extending its life.
CFLs start to dim as they get older due to light output decay, but the change is so gradual that the human eye fails to notice it, until much later. It is said that a CFL produces approximately 80% less light in its advanced years.
Environmental Impact of CFL Lamps
Though CFLs pitches in to reduce the amount of CO2 emission (less heat compared to IL), it’s not rosy as it sounds. CFL lamps contain a small amount of toxic mercury in its glass tubes, so you might want to think twice before you toss it in the dustbin directly. There are guidelines that are a must follow in some countries, on the disposal and recycling of these lamps.
Light Emitting Diode (LED)
When it comes to producing light, LED (or Light Emitting Diode) have a little different approach. No mantra of vapor or wire here, LED lamps generally contain a cluster of tiny LEDs which gives off light collectively.
LEDs get illuminated solely by the movement of electrons in a semiconductor material. A semiconductor material or diode is made up of a positively charged and a negatively charged component. The positive component carries a number of openings for electrons, which are known as holes while the negative component contains free electrons.
When electricity is passed, the excited electrons pass on to the positive holes and emit light in the process. As simple as it may sound, the advantage of LEDs lies in the fact that it gives off a visible blue light.
This blue light can be combined with a combination of red or green phosphors to get the right color of light.
Initially, LEDs have had issues with their brightness, however with the advent of the modern LED lamps that issue has also pretty much mitigated. Now we have LED lamps which can give the same power as a 60-watt incandescent lamp.
Efficiency of LEDs
When it comes to being energy efficient, nothing can beat these lamps, at least for now (well, you know the dramatic speed of science & technology). Where ILs and CFLs lose out on energy in terms of heat, LEDs emit a dramatically lesser amount of heat and is highly efficient. And if we talk numbers — it’s approximately 80% more efficient than IL and 15% than CFLs.
Environmental Impact of LED Lamps
With regards to mother earth, it is said that even LED manufacturing goes light on the environment. A few studies show that even one single lamp contribute a lot in reducing greenhouse emissions dramatically.
But as far disposals go, the aluminum used in LEDs prove to be more hazardous when they are dumped. Hopefully, with efficient aluminum recycling in the future, this problem will soon be mitigated.
Which One to Go For?
Though the underlying purchasing expense of LED lamps is high, it’s no rocket science to conclude which one’s more practical in the longer run. The future of LED is deduced to be so ‘rosy and bright’ that few companies have stopped rolling out CFLs lamps while others have stopped the R&D.
If you look past the huge price gap — a 15 W Philips LED is priced at INR 785 ($11.53) while a similar wattage Philips CFL can be acquired at INR 209 ($3.07) — in the long run, LEDs can prove to be quite effective on the electricity bill. Where I used to pay around INR 1700 previously, a switch over to LED have reduced it to around INR 1300 in overall usage.
Furthermore, LEDs are more durable than CFLs and have longer shelf lives. It’s estimated that an average LED lamp out-lives a CFL lamp almost in the ratio of 4:1. So, that not only means lesser greenhouse emissions but also a better earth (lesser landfills). Plus the robust nature of LEDs is making them a hot favorite among the masses.