It is difficult to meet a person who does not understand measures of length, area, volume, and weight. It is not difficult to calculate time or determine temperature. But if you ask someone about photometric quantities, then in most cases you cannot expect a clear answer. Meanwhile, we live in constant contact with lighting, natural or artificial. This means that we must learn to evaluate it in some way.

Of course, such an assessment is always made by everyone, but most often - purely at the level of subjective perception: is there enough light or not. However, such a “gradation” is precisely subjective and can produce significant errors. The consequences of such incorrect assessments cannot be underestimated - both insufficient lighting and its excess negatively affect both a person’s visual organs and his psycho-emotional state.

Meanwhile, there is a special value - illumination, the value of which is regulated by legislative acts in the field of construction and sanitation. That is, illumination is precisely the quality criterion that allows you to correctly evaluate the organization of a room lighting system. In this article we will talk about this parameter and other photometric quantities associated with it, and see how this can be used in a practical application.

Due to ingrained habit, many continue to believe that the assessment of room illumination can be done in energy units - watts. This misconception is easily explained - we are left with this persistent stereotype as a legacy from the times of complete dominance of incandescent lamps.

Incandescent lamps were produced with different power consumption - 15, 25, 40, 60, 75, 100, 150 and more watts. And every owner of a house or apartment knew from his own experience that for normal lighting in the living room, for example, he must screw three 60-watt bulbs into a chandelier, a “forty” will be enough for a table lamp, a hundred-watt one for the kitchen, etc.

By the way, a clear legacy of this is still the practice used by lamp manufacturers - to indicate on their packaging, in addition to power consumption, luminous efficiency expressed in the equivalent power of old incandescent lamps.

So let's remember the first thing - neither the luminous flux emitted by a lamp nor the surface illumination resulting from it is measured in watts. The watts indicated on the body of the device are the amount of electricity consumed by the lamp, which, through certain physical transformations, is converted into visible light.

Some people of the older generation are generally sure that the luminous output of a lighting device is measured in candles. By the way, this is not so far from the truth, and why will become clear below. But again, this is not illumination at all.

So it makes sense to consider the main photometric quantities in order, from the light source to the illuminated surface. Let’s make a reservation right away – this topic is quite difficult for an unprepared person to understand. Therefore, we will try to simplify the presentation as much as possible and will not overload it with cumbersome formulas. So that there is simply a general understanding of the issue.

Light flow

Light, as is known, has a wave nature. In a certain range of wavelengths, electromagnetic radiation is perceived by the human visual organs, that is, it becomes visible. The approximate boundaries of this range are from 400÷450 nm (red part of the spectrum) to 630÷650 (violet region).

Electromagnetic waves are a carrier of energy - it is the energy of the Sun that provides life on Earth. But let's digress from astronomical categories and return to ordinary light sources.

So, since a source emits light, this means radiation and transfer of a certain energy. The amount of this radiant energy (We) transferred per unit time is called radiant flux (Fe). And it is measured in watts.

However, we are talking about lighting, that is, the perception of color by human vision. And estimating the amount of energy “by eye” means immediately introducing a large error. For example, two sources with equal radiation power, but with different glow colors, will also be perceived by the eye differently.

To unify this parameter, a special physical quantity was introduced - luminous flux (F). This is also an indicator of the power of the radiant flux, but only that part of it that is perceived by the average healthy human eye.

Luminous flux can also be measured in watts (this is rather an energy indicator), or in lumens (light indicator). In practice, lumens are usually used.

For the exact value of one lumen, radiation from the central, green part of the visible spectrum, with a length of 555 nm, was taken as a standard.

So, it is accepted that a radiant flux with a wavelength of 555 nm and a value of 1 watt corresponds to 683 lumens. Why such a strange coefficient? It’s just that the final approval of this unit in the SI system took place in 1979, and the first experiments in photometry with the introduction of the luminous flux indicator began to be carried out long before that. At that time, when electric lighting did not yet exist, and an ordinary candle served as a more or less stable, “reference” light source. And the current ratio of energy watt and light lumen was recalculated over time and passed down to the present day.

Let us remind you once again that the watts mentioned above, which can also be used to measure the luminous flux, have nothing to do with those indicated on the lamp packaging. It shows the consumption of the lamp, that is, the amount of energy that it will “take” from the network. We should be more concerned about its energetic light output - how much visible radiant energy it will “give out”. So, when choosing a lamp, it would be much more correct to pay attention not to ephemeral comparative analogies in watts, but to the clearly indicated value of the luminous flux in lumens.

Luminous output

This is a very interesting quantity in practical terms, since it essentially characterizes the efficiency of the light source. It is important to choose a lamp not based on its electrical power consumption, but on how this power is used when converted into light energy.

So, the luminous output value shows how much luminous flux is produced by the lamp when converting one watt of expended energy. It is clear that it is measured in lumens per watt (lm/W).

The conversion of one type of energy into another is carried out in different ways. For example, in conventional incandescent lamps the resistive principle is used - the glow is caused by a red-hot coil with high electrical resistance. It is clear that this is accompanied by huge heat losses. More efficient are modern lighting devices based on the principles of glow of semiconductor matrices when current is passed or specially selected gas mixtures are ionized. Here, significantly less energy is wasted on unnecessary heating.

It was already mentioned above that the peak of normal perception of light by the human eye occurs at a wavelength of 555 nm. And in ideal conditions, with full transformation electrical energy in a monochromatic light flux of the specified wavelength, that is, with absolutely no losses, it is theoretically possible to achieve a light output of 683 lm/W. This is called an ideal light source, which, alas, does not exist in nature.

The table below shows comparative characteristics for the most commonly used lamps in everyday life - incandescent, fluorescent and LED. It is clearly visible how more economical the use of modern light sources becomes, that is, how the luminous efficiency increases.

(The values ​​in the table are approximate. In any category of lamps there may be deviations in one direction or another - this depends on the quality of the particular model. But the table presents the general picture quite clearly).

Luminous flux, Lm	Incandescent lamps		Fluorescent lamps		LED bulbs
	Consumed Power, W	Luminous output lm/W	Consumed Power, W	Luminous output lm/W	Consumed Power, W	Luminous output lm/W
250	20	12.5	5÷7	41.7	2÷3	100
400	40	10	10÷13	36.4	4÷5	88.9
700	60	11.7	15÷16	45.2	6÷10	87.5
900	75	12	18÷20	47.4	10÷12	81.8
1200	100	12	25÷30	43.6	12÷15	88.9
1800	150	12	40÷50	40	18÷20	94.7
2500	200	12.5	60÷80	38.5	25÷30	90.9

The specific luminous efficiency value is not always, but is still indicated by some lamp manufacturers on their packaging. This may be the inscription “light output” or “Lighting effect”. If not, then it’s easy to determine it yourself by dividing the nameplate luminous flux by the specified power consumption.

It is quite obvious that of all the lamps used in living conditions, LED devices have the best light output indicators - for them this figure reaches 100 lm/W, and may even be slightly higher. But progress does not stand still, and the developers announce an imminent release serial production lamps with a luminous efficiency of about 200 lm/W. But the ideal source is still oh so far away...

By the way, scientists managed to estimate luminous efficiency The sun, and it is not so high: approximately 93 lm/W.

About the luminous efficiency of light sources various types This is also explained in the video below:

Video: What is luminous efficiency, and what is the practical application of this parameter?

The power of light

In physics there is the concept of a point source of light - it propagates radiation exactly the same in all directions. In practice, if this happens, it is extremely rare, and even then - with some simplification of concepts. In fact, the light flux in different directions is uneven. And in order to estimate, let’s say, its spatial density, they operate with the magnitude of the light intensity. And to understand what it is, you will also have to remember the concept of a solid angle.

Let's start with geometry. So, a solid angle is a part of space that unites all rays emanating from one point and intersecting a certain surface (it is called a subtending surface). In photometry, of course, this is an illuminated surface. This angle is measured in special quantities - steradians (sr), and is usually indicated in formulas by the symbol Ω .

The magnitude of the solid angle is the ratio of the area of ​​the subtending surface to the radius of the sphere.

Ω = S/R²

That is, if we take, for example, a sphere with a radius of one meter, then a solid angle of one steradian will “cut” a spot on its surface with an area of ​​one square meter.

Why know this? The fact is that the concept of luminous intensity is directly related to the solid angle. Specifically, a luminous flux of one lumen, propagating in a space limited by a solid angle of one steradian, has a luminous intensity of one candela. Mathematically, this relationship looks like this:

I = Ф/ Ω

And if we talk about the energy intensity of light equal to one candela, then this is 1/683 W/sr.

By the way, the candela is one of the seven basic quantities of the SI system.

Candela literally means candle in Latin. This is exactly that “relic of the past” that was already mentioned above, but it very clearly shows the entire interconnection of quantities.

Let's explain in the figure:

So, there is a point source of light - a candle. Its burning wick emits light with an intensity of one candela (item 1).

In a space limited by a solid angle equal to one steradian (item 2), a luminous flux (item 3) equal to one lumen will propagate. At a certain distance from the source (radius of the sphere - position 4), this flow illuminates the surface of a certain area (position 5). Looking ahead, we will immediately say that if the area is equal to one square meter, then under such conditions in this “light spot” an illumination equal to one lux (lx) is provided.

If we return to the candle as a reference light source, then it is easy to calculate it general light new flow. A complete sphere has a solid angle of 4π, that is, with slight rounding, it is equal to 12.56 steradians. This means that a candle emitting light of one candela in all directions produces a total luminous flux of 12.56 lumens.

It is interesting that not so long ago the emissivity of light sources was assessed “in candles”. For example, they said that you need a “light bulb for sixty candles.” Sellers and buyers understood each other perfectly - a 60 W incandescent light bulb was purchased, although, in fact, these values ​​​​are in no way related to each other in this case, from a physics point of view, are not related. And what’s funny is that it was close to the truth.

Let's see - 60 candles of 12.56 lumens will give a total of 753.6 lumens. Let's look at the table above - an incandescent lamp with a consumption of 60 watts has a luminous flux of approximately 700 lumens. Very close!

But, we repeat, a correct assessment of light sources should still be carried out in lumens.

Light brightness

Another parameter worth considering is the brightness of the light source. The fact is that there is practically no need to deal with point sources. That is, most sources have some specific emitting surface. And with an equal luminous flux, but a different area of ​​light emission, it will be perceived differently by vision.

That is, in essence, brightness is the strength of light emitted from a certain unit area of ​​the visible surface of a light source.

It is clear that the unit of brightness will be candela per square meter.

This is an important value, since the organs of vision, when looking at a light source, react, rather, not to the intensity of light as such, but rather to brightness. When its value is large (over 160 thousand candelas per square meter), the light can cause eye irritation, pain, and tearfulness. Therefore, manufacturers lighting fixtures and produce lamps with frosted bulbs. With virtually no loss of luminous flux, the radiation does not come specifically from an incandescent filament or LED with their small areas, but from a much larger surface area of ​​the bulb. This glow is much safer for the retina of the eye and is perceived much more comfortably by vision.

Surface illumination

Finally, we got to the lighting. This value can be considered the most applied, since it is the illumination of a particular area that evaluates the overall operation of lighting devices.

Figuratively speaking, illumination (E) is the surface density of the luminous flux (F) distributed over a particular area (S). If we approach it with some simplification, then this can be expressed by the following formula:

As we saw above, one lumen of luminous flux on an area of ​​one square meter creates an illumination equal to one lux (lx).

Illumination depends on a number of factors, even if you do not take into account the own characteristics of the light source.

• Firstly, the further the source is located from the illuminated surface, the larger the area of ​​the “light spot” (remember the solid angle cone). That is, the luminous flux is distributed over larger area. Moreover, as we remember, this dependence is quadratic. That is, when the distance changes by half, the illumination will decrease by four times, by three times by nine times, etc.

If we consider a point source, we can apply Kepler’s formula:

We will not repeat the meaning of the quantities included in the formula - they are given above.

• Secondly, the Kepler formula shown above is valid only for a surface perpendicular to the direction of the light flux. In reality, of course, this does not happen often. That is, in the case when the illuminated plane is located at some angle α to the direction of the flow, corrections have to be made for this:

E = (I / r²) × cos α.

Remember - when you need to illuminate a surface as brightly as possible, you point the flashlight perpendicular to it. But if you place it at an angle, the illumination will drop sharply, since the light seems to be “smeared” across the surface.

• Thirdly, the illumination of a particular area also depends on its, so to speak, surroundings. The fact is that most surfaces do not absorb all the light that hits them, but largely reflect it. And thus they themselves become original sources of light.

Let's remember what was said in the section about the brightness of the glow. Yes, indeed, the brightness of such illuminated areas is not particularly high. But the radiation comes from a decent area, and as a result a very significant luminous flux is created.

And the brightness of such an illuminated surface depends both on its illumination and on its diffuse reflectivity, which has a separate name - albedo. The higher the albedo, the brighter the glow. And since it’s brighter, the “secondary” color flow is more studied.

Some illustrative examples reflected light. A sheet of white paper with illumination of only 50 lux will have a brightness of 15 cd/m². The glow of the full moon (and this, as we know, is sunlight reflected from its surface) is characterized by a brightness of 2500 cd/m². And the surface of pure white snow on a sunny day reaches a brightness of up to 3000 cd/m². Quite a lot!

This phenomenon is very widely used in lighting and design rooms. Entire model lines of lamps are produced that are specially designed to be directed towards walls or ceilings, that is, it is the illuminated areas that are included in the work of general lighting of the room. The same effect is used when creating multi-tiered ceiling structures with LED strip lighting.

It is easy to guess that the illumination of the room will depend on the chosen style of its decoration. The same light bulb, say, in a white room will provide much greater illumination than in one painted in dark colors.

Since the final expected result of the operation of lighting devices is the creation of comfortable and healthy lighting indicators in the room, it is the value of surface illumination that is subject to regulation. Legislative acts (SNiP and SanPiN) indicate what illumination should be achieved in various rooms, depending on their purpose.

Thus, the current SNiP 23-05-95 in its updated version (Code of Rules SP 52.13330.2011) specifies the following standard illumination indicators for residential buildings:

Type (purpose) of the premises	Illumination standards in accordance with current SNiP, luxury
Living rooms	150
Children's rooms	200
Office, workshop or library	300
Cabinet for precision drawing work	500
Kitchen	150
Shower room, separate or combined bathroom, bathroom	50
Sauna, locker room, swimming pool	100
Entrance hall, corridor, hall	50
Entrance lobby	30
Stairs and landings	20
Wardrobe	75
Sports (gym) room	150
Billiard room	300
Storage room for strollers or bicycles	30
Technical rooms - boiler room, pump room, electrical room, etc.	20
Auxiliary passages, including in attics and basements	20
Area at the main entrance to the house (porch)	6
Area at the emergency or technical entrance	4
Pedestrian path at the entrance to the house for 4 meters	4

In this case, the assessment of illumination should be carried out on a horizontal plane at floor height. For stairs - both at floor height and on transition platforms and steps.

To assess the level of illumination, special devices are used - lux meters. They consist of a photodetector with a spherical sensor surface, and a converter unit with an analog (arrow) or digital indication of readings.

It is clear that a lux meter is a highly specialized, expensive device that is used by specialists, and which is absolutely not required to have at home. But understanding the basic photometric quantities will not hurt any owner of a house or apartment.

For what? - many may ask. Yes, at least in order to be able to independently plan the use of certain light sources in order to achieve required illumination. After all, the health and general mood of all family members directly depends on it.

The practical position of this knowledge will be discussed in the next section of the publication.

Colorful temperature

To finish the conversation about the main characteristics of light sources, it is necessary to dwell on their color temperature.

With completely equal indicators of the emitted luminous flux, one light bulb can give a warm yellowish color, another - a neutral white, and a third, for example, can glow with a cold shade of blue. How to distinguish them by this parameter? A special color temperature scale has been developed for this purpose.

Let's make a reservation right away - there is no connection between the air temperature in the room or the heating temperature of the light source itself. The glow of a physical body heated to high temperatures is simply taken as a standard.

Any body, if its temperature is above absolute zero, is itself a source infrared radiation. As the temperature rises, the wavelength of this radiation changes, and at a certain moment it reaches the visible part of the spectrum.

Probably everyone has observed this - when heated, a metal rod first turns red, then begins to glow with a bright red light; you can heat it, as they say, “white-hot.” And when performing electric welding work, when the arc temperature reaches very high levels, the melting metal can acquire a blue tint.

It is this gradation that forms the basis of the color temperature scale. It is indicated in Kelvin - and on the scale you can see what kind of glow the lamp will emit.

This color temperature is usually indicated in the lamp labeling. Sometimes it is accompanied by a text explanation, or even a miniature scale showing in which region of the visible spectrum the lamp will glow.

The choice of lamps based on their color temperature depends on what kind of environment you plan to maintain in the room. Of course, a subjective factor will also play a significant role here - that is, the preferences of the owners. And there are no ready-made “recipes” for this. But the table below provides a recommended overview of lamps based on their glow. Perhaps this will help someone when choosing.

Colorful temperature	Visual perception	Possible definitions of the created atmosphere	Typical Applications
2700 K	Warm light	Open, warm, friendly, cozy, relaxing	Living rooms, hotel lobbies, small boutiques, restaurants, cafes
3000 K	White light	Intimate, friendly, conducive to communication	Living rooms, libraries, shops, offices
3700 K	Neutral light	Friendly, conducive to communication, giving a feeling of security, increasing attentiveness	Museums and exhibition halls, bookstores, offices
4100 K	Cold light	Focus-promoting, clean, clear, productive	Training premises, design bureaus, offices, Bolgitsy, large stores, train stations
5000 - 6500 K	Cold daylight	Disturbing, overly bright, emphasizing colors, sterile, tiring over time	Museums, jewelry stores, some offices in medical institutions

Carrying out independent calculations.

As promised, this section of the publication will discuss the algorithm for calculating illumination. More precisely, to be more correct, the calculation has just the opposite direction. That is, we already know the normal illumination value. And calculations should lead us to the result of how many lamps and with what luminous flux will be required to provide it.

General formula for calculations

So, let's start with the formula that will serve as the basis for our calculations.

Fl = (En × Sp × k × q) / (Nc × n × η)

Fl- this is the luminous flux of the lamp that needs to be installed in the lamp. That is, this is the very value that is the purpose of the calculations.

Yong- standard illumination of surfaces, depending on the type of room. It corresponds to the parameters established by SNiP and given above in the table. That is, we start from the standard value.

Sp- area of ​​the illuminated surface. Usually the area of ​​the room appears here if calculated general lighting. But if the goal is to calculate the illumination of a local area (for example, working area), then it is the area of ​​this zone that is substituted.

k- correction factor, which is often called the safety factor. Its introduction takes into account several circumstances affecting the luminous efficiency of lamps. Firstly, many lamps begin to waste their emitting potential over time, or, simply put, to dim. Secondly, the emissivity can be influenced by some external factors- this is the dustiness of the room or, say, a high concentration of steam, which prevents the free propagation of light rays.

Since we are talking about residential premises, where dense steam should not exist, and dust is removed by regular cleaning, then the second group of factors can be discounted. And for the gradual loss of emissivity, the coefficient for different types of lamps can be taken as follows:

Fluorescent lamps (gas discharge): 1.2;

Conventional incandescent and halogen lamps: 1.1;

LED lamps: 1.0.

q- a coefficient that takes into account the uneven glow of certain types of lamps. It is taken equal to:

For incandescent lamps and gas-discharge mercury lamps: 1.2;

For compact fluorescent incandescent lamps and LED light sources: 1.1.

Let's move on to the denominator of the fraction.

Nc- the number of lighting fixtures planned for installation in the room or in a separate zone for which the calculation is being carried out.

n- the number of horns in the lamp planned for installation.

It is probably clear that the product of the last two values ​​shows how many lamps are planned for installation. For example, one five-arm chandelier is installed. Then Nc=1, and n=5. Or you plan to illuminate the room with two devices, each with three light bulbs: Nc=2, a n=3, But if the lighting is provided by one device with one lamp, both of these quantities will be equal to one.

η - luminous flux utilization factor. This correction value takes into account many factors relating to both the characteristics of the room and the specifics of the lighting fixtures planned for installation.

Since it is precisely this coefficient that remains an unknown value, calculations should begin with it.

Finding the luminous flux utilization factor

This value can be called a tabular empirical value. It depends on the area of ​​the room, and on the location of the lamp, and on the main direction of the light flux, and on the finishing of the flux surfaces, walls and floors.

First of all, to enter the table you will have to define the so-called premises index. It takes into account the dimensions of the room, moreover, precisely in the ratio of length and width, since in square room and in an elongated rectangular shape the light flux will still spread differently. And secondly, it takes into account the height of the lamp above the illuminated surface. As we remember, according to SNiP requirements, illumination is assessed on a horizontal plane at floor level.

Important - sometimes the height of the ceiling in a room is confused with the installation height of the lamp. But this is still not the same thing! For example, a lighting fixture can be mounted on a wall (sconce), installed on a stand or placed on a table or bedside table (floor lamp or table lamp), or suspended from the flow at a certain distance from the ceiling surface (chandelier).

The formula probably won't tell you anything. It’s better to suggest using an online calculator to determine this room index.

Today we will talk about room illumination, how it is measured and with what instruments it can be measured.

Important Factors

One of the important factors that is taken into account both during the construction of a building and during its operation is the level of illumination.

This indicator is very important because it affects the health of a person’s eyes, his ability to work, and his physical and psycho-emotional state.

Therefore, room illumination is included in labor protection provisions.

Building lighting is divided into two components - natural lighting and artificial.

Natural is daytime solar lighting, which enters the building through technological openings made in it during construction - windows.

Artificial lighting

At night, illumination is produced artificially - with all kinds of electric lamps.

Artificial lighting can also be used in the daytime with weak daylight, as well as in buildings where it is technologically impossible to install the appropriate number of windows, for example, ground floors buildings or basements.

The state of the atmosphere is also taken into account, geographical position.

In what units is illumination measured?

Illumination is measured in lux (Lx) and corresponds to luminous flux, which falls on a certain unit of room area. Often the square meter of the room is used for measurement. Exist .

The calculation of illumination also includes the characteristics of visual performance.

7 levels of visual work have been defined, which take into account the tension in a person’s eyes when performing a particular job.

The greatest illumination is required for rooms in which high-precision work is performed, while the least amount of lighting is installed for rooms monitoring the production process.

The conditions for performing work and staying in the premises are also taken into account.

This criterion is divided into 4 subcategories - constant work, periodic work with constant stay in the premises, periodic work with periodic stay and simply monitoring communications.

Types of lighting

4 types are used artificial lighting:

• General (with this lighting, a uniform distribution of the light flux is produced over the entire area of ​​the room. It is achieved by uniformly dispersing light sources over the entire area while maintaining the distance between them);
• Local (used for improved lighting of a separate work area);
• Combined (includes general and local lighting);
• Emergency (rarely used. Designed to provide lighting when the main light source is turned off).

Types of lamps for room lighting

Artificial illumination is achieved through the use of electric lamps, which convert electricity into light flux.

At one time, incandescent lamps were the most common. The wide power range of these lamps made it possible to select a light source with the luminous flux required for certain conditions.

Recently, they have become less in demand because they are economically expensive.

The second type of lamps used for lighting is fluorescent.

These light sources are gas-discharge, in which the luminous flux occurs due to the conversion of an electrical discharge by a phosphor into a luminous flux.

These lamps are more economical because during operation they do not spend part of the energy consumed to generate heat, as happens in incandescent lamps.

The third type of lamps used for indoor lighting is LED. This type of lamp is the most economical.

The economic efficiency of all types of lamps is taken from the calculation of the amount of luminous flux emitted by the lamp and the energy costs that go to provide illumination.

According to this calculation, the table of energy consumption to produce a certain luminous flux looks like this:

Table of lamp power consumption when emitting a certain luminous flux
Lamp type	Incandescent lamp	scenic		Luminous flux (Lm)
Power consumption (W)

Light measurements

Indoor illumination is a quantity that can be measured. Measurements are made using a device - a lux meter.

Illumination measurements are carried out separately for natural and artificial lighting.

The lux meter works on this principle - its design includes a photocell, which receives the light flux.

When light hits, it releases a stream of electrons, after which the photocell becomes a conductor of electric current.

Since the magnitude of the transmitted current is directly proportional to the illumination of the photocell, the conducted current acts as an illumination meter.

The instrument readings are displayed on a scale or display.

Light measurements are taken in different places in the room.

A special feature of using the device is its use only on straight horizontal surfaces and away from electromagnetic sources.

The device first determines general illumination premises, and then the illumination of the workplace itself.

Lighting devices differ in design, physical properties and technical characteristics. The parameters of lighting devices raise many questions and disputes, especially the unit of illumination measurement. It is often confused with other concepts, such as luminous intensity or brightness. In addition, many consumers buy lighting fixtures based on the total value, without taking into account heat and light losses.

What is illumination

The concept of illumination is closely related to the amount of luminous flux measured in laboratories using special equipment. The illumination itself can be determined independently, and its value is taken into account by the relevant SNiPs. To calculate this parameter, use the luminous flux, measured in lumens, which is in relation to the area of ​​the illuminated surface. It should hit the surface at a 90 degree angle. Illumination is measured in special units - lux (lx).

The magnitude of the luminous flux has a direct impact on the physical and psychological condition person. Too little lighting depresses the brain, and too bright, on the contrary, has a stimulating effect on brain processes. Such a negative effect causes premature wear and tear of the body and has a detrimental effect on the organs of vision.

Therefore, when drawing up a lighting design and placement of lighting devices, a safety factor must be used that takes into account the likely drop in illumination during operation. Gradually, optical components wear out and become dirty, which leads to a decrease in the brightness of artificial light. In addition, the natural light factor decreases as the reflective properties of surrounding objects gradually change.

Illumination is primarily measured at the workplace. At the same time, sound vibrations are determined, the degree of contamination, electromagnetic and even gamma radiation are taken into account. The measurement results allow you to create the most optimal conditions labor, in accordance with sanitary standards and rules.

In what units is illumination measured?

The unit of illumination measurement should be discussed in more detail. The generally accepted unit is lux, which represents the illumination when a luminous flux of 1 lumen falls on a surface of 1 m2.

How much illumination does the unit of measurement 1 lux actually include? For this purpose, it is necessary to compare several standard parameters based on human physiology, enshrined in strict medical rules and government standards. Without compliance with them, it is impossible to approve any construction project.

An illumination level of 1 lux is created by an ordinary candle located at a distance of 1 m from the illuminated surface. With the help of this simple device, it is quite possible to calibrate a homemade measuring device - a lux meter - with fairly high accuracy.

As examples for comparison, we can take several well-known types of illumination.

• Bright sunlight at noon will be 100-140 thousand lux
• Sky without clouds during the day - 6200 lux
• Desk lamp, illuminating the table - 500 lux
• Illumination in the shade on a sunny day - 430 lux
• The onset of twilight in the evening - 70 lux
• The beginning of the night with moonlight - 1.5 lux.

Light sources and surfaces that reflect light do not always appear as individual points. If the visual organs are able to distinguish their shape, then we will talk about another photometric quantity known as brightness. Her physical properties are similar to the intensity of light, but in this case this relationship will not be absolute. It is proportional to the area of ​​the reflecting or radiating surface.

Brightness, as a physical concept, is the only photometric quantity that the human eye can normally perceive. It is clearly manifested in the properties of large light sources, consisting of a large number of point emitters. Provided they are of the same brightness, the overall light of a large lighting fixture will be perceived as a single whole.

List of basic units of measurement

There are several basic units of measurement that characterize the parameters of light in one way or another. Among them, the most famous and widespread are the following:

• Light flow. Represents the power of light emitted. This is the visible spectrum of radiation associated with the sensation of light perceived by the human eye. This value is measured in lumens (lm). For example, the luminous flux emitted by a 100-watt incandescent lamp is 1350 lm, and LB40 fluorescent lamp is 3200 lm.
• The power of light. The density of the luminous flux relative to the surrounding space. At its core, it is a proportion where the luminous flux is related to the solid angle within which the radiation is uniformly distributed. The unit of measurement is candela (cd).
• Illumination. The luminous flux incident on the surface has a surface density. It is evenly distributed and correlates with the area of ​​the illuminated surface. The unit of measurement is lux (lx), equal to 1 lm/1 m2.
• Brightness. Represents the luminous intensity with surface density in a specified direction. The unit of measurement is cd/m2.
• Luminosity. The luminous flux emitted by a surface with density, which is the ratio of the luminous flux to the area of ​​the luminous surface. The unit of measurement is 1 lm/m2.

Instruments for measuring light levels

The level of illumination is measured by a device - a lux meter. This small, portable device works in much the same way as a photometer. A stream of light radiation hits a semiconductor photosensitive element and begins to tear off electrons from it, which begin to move in an orderly manner. As a result, the electrical circuit closes. In this case, the magnitude of the current is proportional to the intensity of illumination of the photocell and is displayed on the scale of analog devices.

Currently, there are practically no instruments with arrows left; they have been replaced by digital measuring equipment. Each lux meter is equipped with a liquid crystal display and a photosensitive sensor located in a separate housing. A flexible wire is used to connect these two parts together.

Before starting light measurements, the lux meter is set to a horizontal position. Modern GOSTs require that different points in the room be used for measurements in accordance with established scheme. Natural and artificial lighting are measured separately. When performing the procedure, even the slightest shadow is not allowed to fall on the device. There should not be any sources of electromagnetic waves nearby. All these factors can cause interference and affect the measurement results.

The resulting illumination value must be compared with the parameter established by GOST. Based on these data, conclusions are drawn about the sufficient or insufficient illumination of any room or area. After the tests, an evaluation protocol is drawn up.

Illumination and LED devices

When illuminated by LEDs, it emits a large number of heat. To dissipate it, heat-conducting structures made of aluminum, cooling fins and other elements are used that neutralize the effects of heat. When creating new lamps, specialists must take into account the relationship between illumination and heat loss.

Operational difficulties appear when the temperature rises above 50 degrees. In this regard, measurements should be taken approximately two hours after the start of work. LED lamps. To eliminate errors, illumination measurements are performed periodically throughout the working day. It is recommended to conduct such studies at least once a year.

Light has a direct impact on a person's well-being. Insufficient lighting in the workplace can lead to loss of concentration, blurred vision, depressed mental state and low performance. Excessively bright light is irritating to a person and can cause stress. Proper lighting is very important for good performance.

The level of illumination in different types of premises is strictly regulated by sanitary rules and regulations. The sanitary and epidemiological service monitors compliance with these standards.

Units of measurement of room illumination

The numerical value of illumination is equal to the luminous flux that falls perpendicular to the plane per unit surface area. If light falls on a plane at an angle, then the illumination value decreases in direct proportion to the cosine of the angle of inclination of the rays.

According to the International System of Units (SI), the level of illumination is measured in lux. One lux is equal to one lumen (a unit of measurement of luminous flux) per 1m2.

In the absolute physical system of units (APS), illumination is measured in photos. One phot is equal to 10,000 lux. Illumination is a value directly proportional to the intensity of light that comes from the light source. The farther an object is from the light source, the less illumination it receives.

In England and America, a slightly different unit of measurement of illumination is traditionally adopted. It is called a foot-candle and means that the light intensity equal to one candela comes from a source located at a distance of one foot from the illuminated surface.

There are several other units of measurement, but all of them are either derived from lux or are outdated and do not correspond to the generally accepted international system. Therefore, their use is undesirable.

How to measure room illumination

In order to determine the level of illumination in a room, special devices are used:

• Luxmeter.
• Light meter and exposure meter;
• Flash meter;
• Photometer.

The main device for measuring the actual illumination of a room in the presence of artificial and natural light sources is a lux meter. It can be used to:

• carry out illumination measurements for the purpose of certification of workplaces;
• control the compliance of the illumination level with sanitary standards in premises for various purposes;
• determine the compliance of illumination indicators with the calculated values ​​during the installation of lighting fixtures;
• identify the level of decrease in the intensity of operation of lighting devices, and make a decision on the need to replace them.

Luxometer for measuring room illumination

The principle of operation of a lux meter is that a stream of light enters the built-in photocell, and a stream of electrons is released inside the semiconductor. As a result, there is electricity, the magnitude of which is directly proportional to the strength of light incident on the photocell. It is this indicator that is reflected on the scale of the device.

Light meter models are divided into two main groups depending on the method of mounting the sensor:

• with a rigidly fixed sensor (in the form of a monoblock);
• with a remote sensor that is connected using a flexible cable.

To carry out the simplest measurements, it is enough to use a regular monoblock luxmeter without any additional functions. For the purpose of conducting professional research, device models with built-in internal memory and a function for determining the average value of readings are used. In addition, it is possible that the lux meter contains additional light filters, which make it possible to more effectively determine the amount of light intensity emitted by lighting devices with different shades colors.

Models with a remote sensor provide the most accurate readings because they are less susceptible to external influences. In modern lux meters, the measurement result is shown on a liquid crystal display.

Exposure meters and exposure meters are used in photographic equipment. They perform the function of determining the brightness and illumination of the exposure. This is necessary to obtain high-quality photographs. Light meters are divided into built-in and external models.

The flash meter measures the level of illumination during photography using flash lighting devices. In modern cameras it is built in advance and automatically adjusts the flash power. Professional photo workshops are equipped with remote flash meters with an indicating system that can measure not only incident, but also reflected light.

A photometer (multimeter) is a more advanced version of a flash meter and combines its functions with the capabilities of an exposure meter.

What is the light pulsation coefficient and its norms?

Any lighting device emits luminous flux not uniformly, but with a certain number of fluctuations. This effect is difficult to notice with the naked eye. But its impact on a person’s well-being is very significant. The invisible influence of light is dangerous because it is not always possible to recognize it. As a result, a person may experience sleep disorders, depression, weakness, internal discomfort, and disturbances in the functioning of the heart.

Lighting pulsation

The lighting pulsation coefficient is an indicator of the depth of changes over time in the light flux falling per unit surface. It is expressed as a percentage. To calculate the coefficient, it is necessary to subtract the minimum value for the same period from the maximum illumination value for a certain period of time, and then divide the resulting result by the average illumination value and multiply by 100%.

Sanitary regulations set a limit on the maximum value of the lighting pulsation coefficient.

In the place where the main work operations are carried out, it should not exceed 20%. The more responsible the work, the lower the indicator should be. For administrative buildings and offices where intense visual work is carried out, a pulsation coefficient of more than 5% is not allowed.

But in this case, the pulsation frequency of the light flux is taken into account only up to 300 Hz, since higher frequencies are not perceived human body and is unable to have any influence on him.

How to measure ripple factor?

To determine the frequency with which the lighting pulsates, use special device– illumination, brightness and lighting pulsation meter. With its help you can find out:

• room illumination level;
• degree of brightness of artificial lighting devices and monitor screens;
• pulsating waves of light that appear from flickering various types lamps;
• pulsations of illumination of monitors of all varieties.

The operating principle of any luxmeter-brightness-pulsemeter is that a stream of light enters the photosensor, then the signal from it is converted, and the measurement result appears on the liquid crystal display. To determine the pulsation coefficient, it is necessary to analyze the data obtained independently or using a special computer program.

The most popular devices for measuring pulsations are “Ecolight-01”, “Ecolight-02”, “Lupin”. And to analyze the obtained data on a computer, you can use the Ecolight-AP program.

Difference different devices from each other consists of the quality of photocells, their level of sensitivity, the type of battery and other important components.

The highest lighting pulsation coefficient, which even reaches 100%, is observed in. Slightly less pulsating - but they show a small pulsation coefficient (maximum 25%). In this case, the cost and quality of the lighting source does not matter. A high ripple factor can be found even in the most expensive lamps.

Tables of lighting standards for various rooms

For each type of premises, clear standards have been established for minimum illumination levels and maximum permissible lighting pulsation coefficients.

Table 1 - Lighting standards for retail premises

Lighting of the trading floor

Table 2 - Lighting standards for schools

Table 3 – Lighting standards for kindergartens

Table 4 - Lighting standards for residential premises

Table 5 - Lighting standards for medical institutions

Room type	Illumination level, lux	Maximum value of pulsation coefficient, %
Doctors' offices	500	10
Therapists' offices in the clinic	300	15
Dark room in an ophthalmologist's office	20	10
Operating room	500	10
Maternity room	500	10
Functional diagnostic rooms	300	15
X-ray room	50	-
Fluorography room	200	20
Auxiliary premises	75	-
Children's wards	200	15
Wards for adult patients	100	15
Laboratories	500	10

Table 6 – Illumination standards for a car wash

Great importance is given to controlling the presence of pulsation from lighting sources in office premises, you can read more about this. Lighting standards production premises and workshops set clear values ​​for the minimum number of luxes depending on the characteristics of the production process; all the most important things on this topic can be read.

How to reduce lighting pulsation?

There are several methods on how to reduce excessive lighting pulsation:

• The use of lighting devices that operate on alternating current with a frequency above 400Hz.
• Installation of conventional lamps on various phases of a three-phase network.
• Installation of compensating ballasts in the luminaire and connection of power supply to lamps with a shift (the first lamp is with lagging current, and the second is with leading current).
• Use of lamps with electronic ballasts.

The choice of method by which you can achieve the required indicators of the lighting pulsation coefficient depends on technical specifications in each specific case. In some rooms, all lamps are connected to one phase of the network, so their installation to different phases can be difficult.

Most convenient option there may be a purchase that meets all sanitary standards. Separate installation of electronic ballasts into previously installed lighting fixtures is also possible.

Documents regulating illumination standards and pulsation coefficient

The main document that regulates the standards of illumination of premises of all types and the pulsation coefficient is the Code of Rules SP 52.13330.2011 adopted in 2011. This is a new version of SNIP 23-05-95, which takes into account all the basic requirements of Federal laws on safety and energy efficiency, as well as international standards.

The Code of Practice describes in detail the lighting requirements and the maximum permissible ripple factor in public, industrial and residential premises.

Office lighting standards

It is necessary to control the illumination of the room and the degree of pulsation of artificial light not only for the purpose of passing certification of workplaces or a routine inspection of the sanitary and epidemiological station. Violations of sanitary standards in the field of lighting can lead to serious health problems for everyone who works in this room. And this, in turn, will cause a decline in efficiency and a decrease in the profitability of the enterprise.

In residential buildings, light has no less impact on people. Pulsation invisible to the eye can imperceptibly destroy people's health. Only a responsible approach to the choice of lighting fixtures and computer equipment can prevent all negative consequences.

In contact with

Any light source is a source of luminous flux, and the greater the luminous flux that hits the surface of the illuminated object, the better this object is visible. A physical quantity numerically equal to the luminous flux incident per unit area of ​​the illuminated surface is called illumination.

Illumination is denoted by the symbol E, and its value is found using the formula E = Ф/S, where Ф is the luminous flux, and S is the area of ​​the illuminated surface. In the SI system, illumination is measured in Lux (Lx), and one Lux is the illumination at which the luminous flux incident on one square meter of the illuminated body is equal to one Lumen. That is, 1 Lux = 1 Lumen / 1 Sq.m.

As an example, here are some typical illumination values:

Sunny day in mid-latitudes - 100,000 lux;

Cloudy day in mid-latitudes - 1000 Lux;

A bright room illuminated by the rays of the sun - 100 Lux;

Artificial lighting on the street - up to 4 lux;

Light at night with a full moon - 0.2 Lux;

The light of the starry sky on a dark moonless night is 0.0003 Lux.

Imagine that you are sitting in dark room with a flashlight and trying to read a book. To read, you need an illumination of at least 30 Lux. What will you do? First, you bring the flashlight closer to the book, which means the illumination is related to the distance from the light source to the illuminated object. Secondly, you place the flashlight at a right angle to the text, which means the illumination also depends on the angle at which this surface is illuminated. Thirdly, you can simply get a more powerful flashlight, since it is obvious that the illumination is greater, the higher the light intensity of the source.

Let's say a light flux hits some screen located at some distance from the light source. Let us double this distance, then the illuminated part of the surface will increase in area by 4 times. Since E = Ф/S, the illumination will decrease by as much as 4 times. That is, illumination is inversely proportional to the square of the distance from a point source of light to the illuminated object.

When a beam of light falls at right angles to a surface, the luminous flux is distributed over smallest area, if the angle is increased, the area will increase and, accordingly, the illumination will decrease.

As noted above, illumination is directly related to the intensity of light, and the greater the intensity of light, the greater the illumination. It has long been established experimentally that illumination is directly proportional to the intensity of the light source.

Of course, the illumination decreases if the light is obstructed by fog, smoke or dust particles, but if the illuminated surface is located at right angles to the light source, and the light propagates through clean, transparent air, then the illumination is determined directly by the formula E = I / R2, where I is the luminous intensity, and R is the distance from the light source to the illuminated object.

In America and England, the unit of illumination used is Lumen per square foot or Foot-Candela, as a unit of illumination from a source with a luminous intensity of one candela, and located at a distance of one foot from the illuminated surface.

Researchers have proven that through the retina of the human eye, light affects processes occurring in the brain. For this reason, insufficient illumination causes drowsiness and inhibits ability to work, and excessive illumination, on the contrary, excites, helps to activate additional resources of the body, however, wearing them out if this happens unjustifiably.

During the daily operation of lighting installations, a decrease in illumination is possible, therefore, to compensate this deficiency, even at the design stage of lighting installations, a special safety factor is introduced. It takes into account the decrease in illumination during the operation of lighting devices due to contamination, loss of reflective and transmitting properties of reflective, optical, and other elements of artificial lighting devices. Surface contamination, lamp failure, all these factors are taken into account.

For natural light they introduce a reduction factor for the KEO (natural illumination coefficient), because over time, the translucent fillers of the light openings may become dirty, and the reflective surfaces of the premises may become dirty.

The European standard defines lighting standards for different conditions, so for example, if in the office there is no need to consider small parts, then 300 Lux is enough, if people work at a computer - 500 Lux is recommended, if drawings are made and read - 750 Lux.

Illumination is measured with a portable device - a lux meter. Its operating principle is similar to a photometer. Light hits the surface, stimulating a current in the semiconductor, and the amount of current produced is precisely proportional to the illumination. There are analog and digital light meters.

Often the measuring part is connected to the device with a flexible spiral wire so that measurements can be taken in the most inaccessible, yet important places. The device is supplied with a set of light filters to adjust the measurement limits taking into account the coefficients. According to GOST, the instrument error should be no more than 10%.

When measuring, follow the rule that the device must be positioned horizontally. It is installed one by one at each required point, according to the scheme of GOST R 54944-2012. GOST, among other things, takes into account security lighting, emergency lighting, evacuation lighting and semi-cylindrical lighting, and also describes the measurement method.

Measurements for artificial and natural are carried out separately, and it is important that no random shadow falls on the device. Based on the results obtained, using special formulas, a general assessment is made, and a decision is made whether something needs to be adjusted, or whether the illumination of the room or area is sufficient.

Andrey Povny