Not all Led Lighting is as efficient as thought. Do not get Fooled and Choose Best Led Bulbs and Tubes

As far as I can remember I have been seeing Fluorescent lamps in my home, first it was based on inductive blast, later it was based on electronic blast. Fluorescent lamps revolutionized lighting industry and it was the defacto energy efficient lamps for years. Now there is new Kid in the Market, its name is LED lamp, it seeks to replace Fluorescent lamps and says marker say it is is more efficient and more durable. 

Because of media people now think that LED lighting is most efficient and best but it far from reality. Not all LED is created equal so thinking that any LED lamp will be more efficient than florescent lamp, arch lamp, vapor lamps is far from reality. It is said that by adopting LED lighting, you will be saving electricity and money, which might not be far from reality if you have failed to buy efficient LED lamps. So do not get fooled by advertisement and be smart and learn more about lighting.

Before you invest money, you have right to know that Florescent lamp and other kinds of Lamp can be more efficient than your standard LED lamp. Only lamp where without any shred of doubt LED is more efficient is Incandescent lamp.

It is touted that LED has higher per watt luminous efficiency it is somewhat true if we are comparing it Incandescent lamp, but if we will compare it with Florescent lamp it might not be the case.

Florescent lamp, such as tube light, or CFL usually are able to deliver 100 lumens per watt. So LED lamp should either be at par with Florescent lamp in terms of Luminous efficiency or above it, anything below is not acceptable.

It is said that you recover the cost of LED lamp by saving electricity, but you can only save electricity if they are better than Florescent lamp otherwise you are investing more.

Unbranded Chinese LED Lamp are not very efficient and their wattage rating is not true. You can go to YouTube and just check the video regarding this problem. Branded LED lamps cost a lot, they can cost 2 - 3 time the cost of standard Florescent lamp.  You can only recover the cost of LED lamp of efficiency of Lamp is at least 1.25 times more than Florescent lamp. If per watt efficiency is same, then in way you can recover the cost within reasonable period of time and there is no guarantee that these LED Lamp will not fail. Depending on brand they have failure rate of up to 3%.

It is interesting to note that production cost of both Florescent lamp and LED lamp is more or less same but LED lamps are so much hyped that their cost difference can be 2-5 times higher than Florescent lamp.

I still use good Old Fluorescent Tube Lights. Why You might ask !

On average a modern Fluorescent lamp will have luminous efficiency of 85-100 per watts. Even till date I use Fluorescent tube because I cannot find anything that give better return on my investment. Here where I live a best Fluorescent 36 watt tube costs around 1 dollar. Whole set costs 5-7 dollars depending on the manufacturer. A 20 watts LED tube costs more, for same luminous efficiency. 

Fluorescent lamp blast and LED lamp step down power convector has same failure rate as both are a kind of Switching power supply. Only LED has more life in terms of brightness otherwise average life rating of good Fluorescent tube is same. Considering return on investment, Fluorescent lamp is way cheaper and more efficient in terms of luminous efficiency at least where I live.

I have adopted LED lamps, for lower wattage and is using it instead of CFL as cost is more or less same and LED lamp has more life than CFL and better efficiency. For anything above 20 watts, I am still using Fluorescent lamp, because of its cost and efficiency.

If you want to know quick and dirty way to buy LED lamps, here is the answer.

Now you must be thinking it must be tricky to choose a decent and efficient LED lamp, but I must tell you are wrong, you just need to remember one thing and that is number 100. Most Florescent lamp sold here where I live have luminous efficiency of 50-100 per watt depending on type. Small CFL lamps with lower watt rating are worst in terms of efficiency and have efficiency around 55, average cfl has efficiency around 60-65 and one such sub as tubes have efficiency around 90-100. So I just check the specification before buying the LED lamp or tube.

If I want to buy a 10 watts LED lamp, it should at least be rated for 750 lumens. Minimum luminous efficiency per watt I am willing to settle for is 75 lumens per watt for CFL replacement and 90 lumens per watt for Fluorescent tube, else I will not buy that lamp. Second thing you must keep in mind is the cost. A LED Lamp price should not cross price range which is two times than that of Florescent lamp for same wattage.

So here is everything you should know about lighting.

1. Lumens Per Watt 
2. Life of LED Chip.
3. Color temperature.
4. CRI (Colour Rendering Index) 
5. Heat sink 
6. Power Factor 

What is lumens per watt? What is Lumen ?

In general terms Lumens is SI unit of luminous intensity or luminous flux. Lumens denotes the amount of light emitted. Lumens per watt, is amount of light emitted per watt. Higher the Lumens per watt better will be efficiency of that lamp. 

Incandescent light bulb or lamp or tungsten filament lamp has lowest efficiency. Most of the energy is wasted in form of heat. They produce more heat than light. 95% of total energy is emitted in form of heat. Only on average around 5% of energy is converted to light. Their luminous efficiency is around 15 lumens per watt. So at 100 watts these lamps produce only 1500 lumes. A typical Fluorescent or LED lamp will only take around 30 watts to produce this much light.

One great thing about this lamp is that it can tolerate a lot of heat, while LED and CFL cannot and its construction is rather easy, so for this very reason it is used in microwave oven for lighting. Most electronics cannot survive long in heat at high temperatures.

So if you are going to buy a Led Lamp, you should first and foremost consider the Luminous efficiency, higher efficiency is better. 50 is lowest you will find in the market 150 is maximum, theoretical maximum reached was 200 when I last checked.

So a 8 watts lamp with 100 lumens per watt will give twice more light than one having 50 watts lumens per watt. Higher lumens per watt is key. You should look for at least 90-100 lumens per watt.

What is Life of LED Chip?

It simply means for how many hours or days it LED will last before it dies. In this regard you do not need to worry, you see my 15 year old LED lamp display is working just fine, and it remain on almost all the time. On average depending on LED and manufacturing technology and quality, LED can survive for anywhere in between 20000 hours to 50000 hours, without much problem. 

What is Color Temperature of Light ?

Color temperature is comparison between two kind of light source. Color temperature in lame terms essentially means how yellow or how blue is light. Colder temperature shifts towards blue tint and warm towards yellow. 

Incandescent light has temperature of around 2400K.

Depending on what kind of light you want there is three grading of temperature.

• Warm Soft White (2700K – 3000K), 
• Bright White/Cool White (3500K – 4100K),
• Daylight (5000K – 6500K).

Here is the color temperature gradient along with its source for your understanding.

not my image, it is from
http://www.lamptech.co.uk/Documents/FL%20Colours.htm

Temperature	Source
1700 K	Match flame, low pressure sodium lamps (LPS/SOX)
1850 K	Candle flame, sunset/sunrise
2400 K	Standard incandescent lamps
2550 K	Soft white incandescent lamps
2700 K	"Soft white" compact fluorescent and LED lamps
3000 K	Warm white compact fluorescent and LED lamps
3200 K	Studio lamps, photofloods, etc.
3350 K	Studio "CP" light
4100 – 4150 K	Moonlight
5000 K	Horizon daylight
5000 K	Tubular fluorescent lamps or cool white / daylight compact fluorescent lamps (CFL)
5500 – 6000 K	Vertical daylight, electronic flash
6200 K	Xenon short-arc lamp
6500 K	Daylight, overcast
6500 – 9500 K	LCD or CRT screen
15,000 – 27,000 K	Clear blue poleward sky

Incandescent light makes everything yellowish it adds yellowish tint. Warm light will add yellowish tint. Day light is neutral like most Florescent light or it can have slight hue of blue.

What is Color Rendering Index, CRI ? Why is it important ? 

Just like Color Temperature of light, it is also used to asses the light and its quality. In short it is also a comparison between two light source. It is comparison between effect of illuminant on a object and how that object is perceived in that illuminant's light. You can say that CRI denotes color accuracy. Light from Sun or any black body radiator will have CRI of 100, CRI can go negative, stating that color displayed in that light is not at all reliable.Number closer to 100 means under that lighting condition things will look realistic and natural as they look under sun light.

Here is a light source, temperature and CRI chart for your reference.

Light source	CCT (K)	CRI
Low-pressure sodium (LPS/SOX)	1800	-44
Clear mercury-vapor	6410	17
High-pressure sodium (HPS/SON)	2100	24
Coated mercury-vapor	3600	49
Halophosphate warm-white fluorescent	2940	51
Halophosphate cool-white fluorescent	4230	64
Tri-phosphor warm-white fluorescent	2940	73
Halophosphate cool-daylight fluorescent	6430	76
"White" SON	2700	82
Standard LED Lamp	2700-5000	83
Quartz metal halide	4200	85
Tri-phosphor cool-white fluorescent	4080	89
High CRI LED Lamp (Blue LED)	2700-5000	95
Ceramic discharge metal-halide lamp	5400	96
Ultra High CRI LED Lamp (Violet LED)	2700-5000	98
Incandescent/halogen bulb	3200	100

Why do LED need heat sink?

There is a glitch with LED that are being used in Lamps, they tend to heat, and thus their life span is reduced if sufficient cooling is not provided. Higher the wattage of LED chip the more they will heat. Heat is bad for electronics, heat destroys electronics. Most Chinese Led Lap do not use heat sink, such bulb has lower life than one which use Heat Sink.

What is PF or power factor ?

It is used to measure the efficiency of electrical and electronic circuit. It is ratio between real power and apparent power. Real power is what can be used to perform some kind of work and apparent power is product of voltage and current. In real world scenario power factor will always be lower than 1. Closer to 1, the better is circuit and more efficient is the circuit or electrical load. 

Usually electronics can have power factor from .7 to .9, depending on country you live in depending on law it can be .7 to .9 as minimum value. Higher value is better and desirable. As far I know and I have seen, almost all switched power supply has power factor of at least 0.8.

So you must be wondering, how power factor affects, consider you have a bulb, it has power factor of .8, it means for every 100 watts it takes it is not able to use 20 watts . So essentially that 20 watt is wasted.

LED lamps are good and are gradually replacing CLF and Incandescent light but they are over hyped and expensive. LED lamps can tend to be very expensive if you cross 18 watts domain and its efficiency is not better than Fluorescent Tubes or other kind of lamps. In 40 watts and above range, Fluorescent Lamp is better, cheaper and has mean efficiency of 90 Lumens per watt and as far as life goes, good brands have tubes which are rated for they are too rated for 50,000 to 62,000 hours. Make sure you pay close attention to cost, efficiency and actual technical data before making the decision. Do fall for marketing hype that Led is be all and end all solution to your Lighting Needs.

If you have any doubt regarding my review and verdict or this product, feel free to message me or comment below to clarify your doubts. I hope that my article has helped you.

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