- How are lamps classified according to the characteristics of the luminous flux
- How much light does the lamp give
- What color the lamp shines
- How a lamp renders colors
The article is devoted to the selection of bulbs for use in lighting systems. In the first part, we will pay attention to the features of the luminous flux: we will deal with the optimal level of its intensity, with the color temperature of the glow and the ability of lamps to transmit the colors of objects.
In the middle of the nineteenth century, electric lamps were invented, and already in the second half of this century, rich in innovations, they slowly began to compete with gas artificial lighting. At the beginning of the twentieth century, even skeptics realized that new light sources simply had no competitors. At the moment, in various areas of life, people use hundreds of options for electric lamps that have their own technical and operational characteristics, and, therefore, they are “sharpened” for specific tasks. In principle, four types of electric lamps can be distinguished according to the technology of obtaining light:
- Incandescent lamps (a spiral made of refractory metal under the influence of current heats up in a protective gas environment and glows). This category also includes halogen light sources..
- Gas-discharge lamps (glow is formed when electricity acts on a mixture of inert gases). These include luminescent, metal halide, sodium, mercury.
- LED lamps (light is obtained by passing direct current through semiconductor crystals).
- Arc lamp (light waves are emitted by an arc that appears between two electrodes).
Since the traditional incandescent filament, glowing in vacuum under tension, an alternative appeared in the form of other technologies for obtaining light, it turned out that there is no universal light bulb. For certain conditions, it makes sense to use some specific light bulbs, which allows you to achieve a certain functional advantage or economic effect, which is especially important against the background of the general struggle for energy efficiency. When making a choice of bulbs for the home, we first of all need to focus on the main characteristics of the light that they generate, but we also should not lose sight of the operational features of the products we are interested in, because the durability and economy of the acquisition depend on this. In specialized retail outlets, you can buy a light bulb for any conditions, you only need to correctly identify these conditions.
How are lamps classified according to the characteristics of the luminous flux
In this case, we are interested in such a concept as “quality of light”. Obviously, ordinary sunlight is the most favorable for a person in all respects, many of which, meanwhile, are unattainable for technologists. Therefore, our idea of the efficiency of a particular lamp depends on how close to natural artificial lighting will turn out. What is a high-quality comfortable light made of? There are only three objective factors:
- first of all, it is its quantity;
- we may also be interested in the color of the glow, which varies from yellow to white and light blue;
- another point that rarely falls into the field of view of consumers is the ability of the lamp to transmit the colors of objects.
How much light does the lamp give
Lack of light is the main reason for the negative perception of the lighting system and bulbs in particular. If the room is too dark, then first of all we overload our vision. Also, experts note that a person’s general psychological condition worsens in such gloomy conditions. The effect has long been known, in which a well-groomed, but poorly lit dwelling seems dirty, and a dark room is somehow uncomfortable and inconspicuous. However, this effect also has the opposite effect: give more light – get coziness, comfort and expressiveness..
Interestingly, in the case of light, it is impossible to overdo it, since during the day it is a thousand times brighter on the street than in the room near the window, and with the help of bulbs we only slightly improve our living conditions. In other words, there is never a lot of artificial light, everything is limited only by issues of saving electricity, the cost of lamps. However, it is very important to comply with the lighting standards that are adopted in the construction business..
The illumination level is measured in special units – Lux. This indicator characterizes the strength of the luminous flux per a given area. For different premises, the sanitary standards for illumination are different. For example, you can read at 30 lux; 100 suites are enough for a bedroom, a corridor, an entrance hall; a bathroom and a living room will require 200 suites; office – from 300 suites; operating room – at least 5000 lux. For reference, the Sun at noon provides us with an illumination of about one hundred thousand lux.
It should be noted that the illumination of a room depends not only on the power and the number of bulbs. Here, a significant influence on the situation is exerted by:
- reflectivity of all surfaces (walls, ceilings, floors, furniture, curtains – worsen or improve illumination);
- technical characteristics of luminaires (they can narrowly focus beams, absorb them with shades, direct, diffuse …);
- the distance from lamps to work surfaces, for example, a desk (with an increase in the distance between the light source and the investigated area, the illumination per square meter drops significantly, from ceiling to floor – at times).
And yet, how to choose the right bulb and how many do you need? We used to measure the performance of light sources with “parrots”, or rather incandescent lamps. As a rule, many manufacturers select the appropriate equivalent for their specific products, for example, “replaces a 150-watt incandescent lamp.” The power consumption, of course, affects the brightness, but this is not the only determining parameter, especially when comparing lamps of different types. To assess the efficiency of a lamp as accurately as possible, it is better to take a look at the special units of measurement. In this case, we are interested in Lumens, do not confuse with Luxes. Approximate figures here are as follows: about 1000-1200 lumens are given by a hundred-watt incandescent lamp, 25-watt fluorescent lamp (including the “housekeeper”), 8-watt LED source, 50-watt “halogen”. By the way, this is how we see the comparative efficiency, or “luminous efficiency” of various types of lamps, which is measured in lm / W.
Practical calculations have shown how many light sources are needed to obtain at least the minimum level of illumination in an average room. Accordingly, tables are displayed, which indicate the approximate power indicators for a square meter. For example, for a living room to achieve an illumination rate of 200 lumens (using incandescent lamps), it will take about one 100-watt lamp per two squares of floor space. Applying efficiency, it is clear how many other types of sources are needed. It seems that the numbers are overstated, but this only proves how “under-lit” our homes are. It is interesting that the European standards of illumination are several times higher.
What color the lamp shines
Many have noticed that light bulbs do not generate the same glow. Some light sources give off a “warm” yellowish-red light, others give off “cold”, almost bluish rays. This characteristic of bulbs is called chromaticity, it is measured and indicated in kelvin. This property of light is also called the glow temperature, since bodies, having a certain temperature, create the glow of a specific spectrum. A reddish-yellow color is given by lamps with indicators of 2450-3200 K. If the package contains numbers from 3200 to 5000 Kelvin, then this lamp will shine with a neutral white light, everything over 5000 K creates an already cold glow and shifts towards blue and purple.
Incandescent lamps, including halogen lamps (about 3000 K), are always warm and yellow, while normal white and cool white are inherent in LEDs. As for fluorescent lamps, they can generate the widest color range of luminescence (from 2700 to 6500 K), so this is where the most attention should be paid to the choice. The special color of the lighting does not give us any technical dividends, so you can choose lamps based on your personal preferences. Note that most users prefer a neutral white color, apparently, since it corresponds to the temperature of the Sun’s glow – 5400 Kelvin.
How a lamp renders colors
This characteristic shows how accurately the colors of objects illuminated by a particular lamp are reproduced. Since lamps work in a given and often limited spectrum, they will necessarily distort the real color of the surrounding bodies – we again compare it with sunlight. Using this phenomenon, you can manipulate colors, for example, slightly pink highlighting sausages in stores or blue – the water surface of the pool. For housing, an ideal indicator, similar to the results of a heavenly body, will be optimal..
This characteristic of lamps is called the color rendering index (CRI), it is also denoted as Ra. The standard is considered to be 100 Ra, but a person quite normally perceives color rendering in 60–70 Ra. Incandescent and halogen lamps have the highest rates, fluorescent sources are slightly behind (on average, about 85 Ra, but there are expensive ones – up to 95 Ra). LEDs reveal the color of objects a little worse – from 75 to 85 Ra. Mercury lamps, used in manufacturing and for street lighting, “make” only about 50 Ra. Outsiders are sodium light sources (mainly used on the streets) – about 25 Ra.
We figured out the quality parameters of the light of the lamps, but going to the store with only these data would be a big mistake. In the second part of the article, you will find out what technical characteristics of bulbs you need to pay attention to, in it we will also discuss the efficiency of various light sources.