It’s not a secret anymore that LED is the greenest, cost and energyefficient lighting technology we have. So there’s no sense to write about its advantages over traditional methods, especially since advertising has made all the job.
So let’s stop squandering the time and come down to essentials. The question is:
It is worth noting, that costeffective doesn’t mean cheap. By saying that the bulb is costeffective we mean that using it will lead to maximum lighting costs decrease. To make it clear we’ll compare a few brands and select the most budgetfriendly model.
Before ranking the bulbs, we need to define the characteristics we’ll be comparing. Such factors as price, lifespan, and wattage come at first. Some advanced users may also note luminous efficacy. But separately none of these properties can define the real costeffectiveness.
Incandescent bulbs have already proven that price is not the most reliable indicator. The bulb may cost a few cents but consume the tons of energy.
Usually, the lower is the wattage the dimmer is the light. So running after low consumption we are risking to purchase the bulb which is not bright enough for our needs.
Luminous efficacy is quite a convenient effectiveness indicator. It shows the number of lumens produced on 1 Watt of consumed energy. So the higher is the number the more effective it uses energy and saves your money.
However, it may be insufficient for selecting the best model. You must admit that when you need to buy a new lamp once in a few months that’s not an economy. So long lifespan matters.
The experience of using LED lamps shows that in determining the economic effects of the product is necessary to consider all the abovementioned features, namely:
— price;
— consumption;
— luminous efficacy;
— durability.
The most comprehensive measure of the light efficiency is the measure of expenses number for a certain period of time (hour, day, year) to maintain light levels.
In other words:
In the form of a simplified formula this definition will look as follows:
Therefore, the smaller is X the more economical is our light.
There is a certain number of characteristics from which we begin our selection:
— the light bulb's brightness, its luminous power;
— design (shape, lamp base, etc.);
— type of light (warm, cold, neutral);
These characteristics determine whether the selected lamp is suitable for our room or not. They also affect the price determination and characteristics that are mentioned above in one way or another. For example, the maximize of the luminous input needs the increase in power, the same wattage "cold" bulbs shine brighter than "warm", etc.
In our case it would be reasonable to "take off the table", i.e. we will select several bulbs from different companies and price categories but with a similar design, brightness and color temperature and try to determine which of them is the most economical.
 Jooby Décor LED Bulb E27, 4.2W  Philips MAS LEDbulb DT 640W B22 A60 CL  Osram Parathom Classic A 40 5 W/827 E27 FR 

Price  EUR 13.4 
 115 UAH 

Input power  4,2W  6W  5W 

Durability  60 000 h 
 15 000 h 

Luminous power  470 lm 
 
Color temperature  2700 K 
 
Lamp base  Е27 
 
Luminous efficacy  112 lm/W  78,3 lm/W  94 lm/W 

Our expenses will be divided into 2 groups and we bring both to a certain period of time:
Purchasing of new lamps
On buying, we pay a certain amount equal to the price of the bulb. The next time such a transaction needs only after the lifetime of the bulb. For recount, we divide the price of the bulb on its lifetime.
For example, if the lamp costs 200 UAH and works 10 000 hours than each working hours costs 200/10 000 =0,02 UAH.
Rate for electricity consumption
In other words, it's electric power bill. This is a sum that we pay for the quantity of power consumption kWh.
For example, a lamp of 100 watts consumes 1000 watts or one kWh while operating 10 hours. If the country has a tariff rate at 1.29 UAH/kWh, then it will cost 10 hours of its work. Therefore, one working hour will cost 1.29/10 = 0.129 UAH.
Let's add our formula:
And move on to comparing our competitors.
 Jooby Décor LED Bulb E27, 4.2W 
Philips MAS LEDbulb DT 640W B22 A60 CL 


Tariff rate (Ukraine)  129 kop.for 1 kWh 
 
Purchase of new lamps
 0,000223 EUR/h  0,01156 UAH/h  0,0077 UAH/h 

Payment for electricity
 0,005418 EUR/h  0,00774 UAH/h  0,00645 UAH/h 

Total input for hour  0,001423 EUR  0,0193 UAH  0.01415 UAH 

Total input for day  0,0341 EUR  0,4632 UAH  0.3396 UAH 

Total input for year  12.45 EUR  169 UAH (+5,95 EUR)  123.9 UAH (+2,11 EUR) 

The unconditional winner in this competition is the Jooby Décor light bulb. The difference of 2 euro seems insignificant. But on the scale of large companies where the count of light bulbs goes to hundreds the amount of saving costs can be several thousand.
Using these rules, you can compare any models. But let’s outline a few key points firstly:
1. Do not neglect any indicators when choosing a LED lamp. If the difference is small in small quantities, then on the scale of a large project, the savings can be a round sum.
2. It should be mentioned that the price is of less importance in the longterm perspective than the lamp's durability and power. So, if you don’t have time for detailed calculation than it is worth paying attention to these characteristics.
3. While comparing lamps of different brightness you should take into account their quantity. To compare the bulbs in 900 and 470 lumens, the costs of the second you have to multiply by 2 because exactly this amount will be needed to create a comparable level of illumination.
4. In pursuit of economy don’t neglect quality. Features such as dimmability, low flicker, and a high color rendering index will affect the price of the LED but without them, you don't get the satisfactory product.