In Soviet times, choosing a light bulb, consumers focused on the number of watts in it. The more of them, the brighter this device shone. However, today (when many new varieties of lamps appeared on store shelves), one often has to deal with such a concept as “lumen”. What is it, how is it different from a watt and what kind of unit is called lumen per watt? Let's find the answers to these questions.
What is a "lumen"
In the middle of the twentieth century. in order to avoid confusion in units of measurement between different countries, a universal SI system was introduced. It is thanks to her that we have watts, amperes, meters, kilograms, etc.
According to her, the unit of measurement of light flux (visible electromagnetic radiation) is the lumen (lumen). In fact, these units measure the amount of light emanating from its source.
Also to the question about what is “lumen”, one can answer that this is the name of a famous Russian rock band from Ufa. Having started its activity in 1998, for almost twenty years it continues to remain beloved by many listeners in the Russian Federation and abroad.
Origin of the word
Having learned what lumen is, it is worth clarifying where this word came from in the Russian language.
Like most unit names in the SI system, the term in question is Latinism. It is formed from the word “light” (lūmen).
At the same time, individual linguists argue that the noun could be formed from the pre-Indo-European word leuk (white) or from lucmen (the meaning is not exactly established).
What is the difference between lumen and luxury
Considering the meaning of the word "lumen", it is worth mentioning such a close concept to it as "lux".
Both of these terms refer to light energy units, however, lumen is the entire light emitted by the source, and lux is the amount that reached the illuminated surface, and was not stopped by any obstacles with the formation of shadows.
The interdependence of these units can be reflected with the following formula: 1 lux = 1 lumen / 1 square meter.
For example, if a lamp illuminating an area of 1 m 2 emits 50 lumens, then the illumination of this place is 50 lux (50lm / 1m 2 = 50 lux).
However, if all the same lamp with the same amount of light is used for a room of 10 m 2 , then the illumination in it will be less than in the previous case. Only 5 suites (50lm / 10m 2 = 5 lux).
In addition, such calculations did not take into account the presence of various barriers that prevent the achievement of surface light rays, which significantly reduces the level of illumination.
In connection with this situation, in any country in the world there are lighting standards for various buildings. If it is lower than them, the person’s vision receives less light and worsens. For this reason, when deciding to make repairs or rearrangements in your home, it is always important to consider this nuance.
There are also a number of design programs in which such calculations are performed automatically.
Lumen and watt
Having learned the difference and significance of lumen and luxury, it is worth paying attention to another SI system unit - watt.
Due to the fact that they are used to measure the power of light bulbs, some believe that these units can be freely correlated. However, this is not quite true.
The fact is that in watts the power of the energy that the bulb consumes is measured, and in lumens the amount of light that it emits.
In the days of the existence of only incandescent lamps, it was easier to calculate the amount of light from such a device. Since a 100 W light bulb gave out about 1600 lm of light. While a similar device in 60 W - 800 lm. It turned out that the more energy was consumed, the better the lighting.
But today is not so. In recent decades, several new types of light sources have been invented (LED lamps, fluorescent, etc.). Their advantage is profitability. That is, they shine brighter with less energy used.
In this regard, if necessary, to make up the ratio between watts and lumens, it is necessary to take into account the type of lamp and look for its aperture in special tables.
It is worth noting that the average person sometimes does not want to readjust and understand all these subtleties. Therefore, most domestic manufacturers of new type of bulbs on the labels indicate not only the number of lumens, but how much less watt this device consumes (compared to an incandescent lamp). For example: a 12-watt lamp produces light as if it were 75 watts.
Unit of measurement "lumen per watt": its value and scope
Although watts and lumens belong to different categories, together they are a unit of measurement of the light output of the device. Lm / W is an indicator of the efficiency of a light source. That is, how much energy it consumes and how much light it emits at its expense.
For example, a classic 40 W incandescent lamp has a light output of 10.4 lm / W. Moreover, for an induction lamp with the same power, this indicator is much higher - 90 lm / W.
For this reason, choosing a lighting device for yourself in the house, you should still not be too lazy, but find out the level of its light output. As a rule, such data is on the labels.