When we talk about lumen per watt we understand higher the number better the LED chip. IF you are with me, lets explore the following scenarios.
First scenario: Hypothetically speaking if a chip from Company "A" consumes 1 watt and gives out 100 lumens and a chip from Company "B" gives 120 lumens using 1 watt. Which do you think is the better chip?
Of course the chip from Company "B" is a better Chip than the one from Company "A" and it is better by 20%.
In a second example: Company "C"'s light bulb gives 300 lumens total flux but consumes 5 watts and Company "D"'s light bulb also gives 300 lumens but only consumes 3 watt, then which is the better bulb?
Of course the bulb from Company "D" is far better than the other one: since it consumes 40% less electricity to give you the same amount of light.
The third scenario is actually a combination of both examples mentioned above. Lets say a light bulb from Company "E" produce 200 lumens and consumes 5 watt and a Helios light bulb from U-Tron produce 300 Lumens but consume only 3 watt. How much better is the Helios U-Tron?
The US Department of Energy is educating the public to use the Efficacy as the unit of measure when its comes to the quality of an LED light bulbs. Its works like this, take the total light flux and divide by the total wattage of the bulb and you get a number that's called "Efficacy". In the third scenario the Efficacy of the bulb from Company "E" is 40 LPW and that for Helios from U-Tron is 100 LPW.
Conclusion:
So if you pay RMB40 Yuan for the light bulb from Company "E" this should be equal to paying RMB100 Yuan for the Helios from U-Tron. A very simple argument you will agree: so am I correct?
Correct, but not quite so. Because we haven't taken into account the extra 2 watts of excess electricity you will be wasting every time you use the light bulb from Company "E". Although this may not seem to be a lot of money, it is money you could have saved it if you had made the right choice at the beginning.
Now having said that, let me show you how much money you would be wasting by making the wrong choice and buying the inferior product.
Lets take a 24/7 application such as a public underground parking garage. KWA = 2 watt x 24 hours x 365 days / 1000 = 19.27. Now if you multiply this number 19.27 by the price you pay for your electricity (In Beijing the price of electricity is RMB1.1 Yuan per KWA for commercial establishments) you can calculate the cost of the wasted energy. So if the bulb is used for 5 years then you are going to waste RMB 96.58 Yuan per every bulb.
