How is illumination measured (natural and artificial lighting)

Main characteristics of light

A person sees a spectrum of colors - a small part of the range of electromagnetic waves. Its characteristics affect the comfort of the living environment and human well-being. There is a definition for one of the properties - luminous flux (F), which is measured in lumens (lm). The power of the luminous flux of the source characterizes the evoked sensation of light perception. According to its distribution, light flows are distinguished for a closed space: direct, diffused, reflected. The more light, the higher the number of lumens.

Important! This parameter does not determine the intensity, brightness or performance of the glow, because it takes into account the entire diffuse flux. In order to measure the luminous flux it takes a lot of time and it is necessary to take into account the spatial characteristics of the phenomenon

Basic characteristics of light emissions

The main characteristic of the source is the luminous intensity (I), which determines the intensity of radiation in the direction of the flow. It is calculated through the quotient of the luminous flux (Ф) and the solid angle (ꭥ) in steradians (sr), within which it is distributed. In SI, the unit of luminous intensity, the candela, is denoted cd.

Solid angle

Important! A wax candle emits about one candela (from the Latin candela), and previously this unit of measurement was called a “candle”

The candelas value shows the light emission of a point light source in its most intense direction.

Lamp buyers usually rate brightness by the power consumption (W) of the source. With good brightness, you get a clear and contrasting vision of objects. However, both weak and very bright light is unfavorable for human activity. Brightness (L) is determined by the luminous intensity density in the direction of the surface and is calculated by dividing I by the area of ​​projection onto a perpendicular surface (depending on the cos angle).

The brightness index (L) of light is measured in cd/m². The main characteristic of the perception of light sensation by the eyes is the brightness of the illuminated surface or source.

Light units

Luminous efficiency (H) measures the efficiency of converting electrical power into light. During the transition from electrical energy to light, losses appear, which causes a decrease in the brightness of the radiation. Light output is measured in lumens per watt. You can calculate the luminous flux by knowing the average luminous efficiency.

LED lamps have practical light output (losses less than 5%).

Important! There are quality standards for lighting for indoors, as well as for plants or animals. Illumination is characterized by the ratio of luminous flux to surface area

Lighting units

Workplace illumination

Lighting is extremely important for humans. With the help of vision, a person receives most of the information (about 90%) coming from the surrounding world. Light is a key element in our ability to see, evaluate the shape, color and perspective of objects around us. Lighting affects not only the functioning of the visual apparatus, that is, it determines visual performance, but also the human psyche and emotional state. Researchers have accumulated a significant amount of data on the biological effects of visible light on the body. A comparative assessment of natural and artificial lighting based on its effect on performance shows the advantage of natural light. The leading factor determining the biological inadequacy of natural and artificial light is the difference in the spectral composition of radiation, as well as the dynamism of natural light during the day.

Workplace illumination

When working under poor quality or low levels of lighting, people may experience eye fatigue and fatigue, leading to decreased performance. In some cases, this can lead to headaches. The reasons in many cases are too low light levels, glare from light sources and brightness ratios that are not well balanced in the workplace. Headaches can also be caused by lighting pulsation, which is mainly a result of the use of electromagnetic ballasts for discharge lamps operating at a frequency of 50 Hz. From an occupational safety point of view, visual ability and visual comfort are extremely important.

In order to provide the conditions necessary for visual comfort, the lighting system must meet the following prerequisites:

• sufficient and uniform lighting
• optimal brightness
• no glare or glare
• appropriate contrast
• correct color scheme
• no stroboscopic effect or light pulsation

Each type of activity requires a certain level of illumination in the area where this activity is carried out. Typically, the more visually impaired, the higher the average light level should be. It is important to consider light in the workplace, guided not only by quantitative, but also by qualitative criteria.

The following quality characteristics of lighting and ways to improve them can be identified:

Direct shine

High-brightness surfaces within a person's field of vision can produce an unpleasant, uncomfortable sensation or cause a state of blindness. As a result, visual performance decreases sharply. Sources of direct glare are lighting installations and light sources.

Direct gloss reduction can be achieved:

• increasing the installation height of lamps
• reducing the brightness of lamps by covering light sources with light-diffusing glass
• limiting the light intensity in directions forming large angles with the vertical, for example, using lamps with the required protective angle
• reducing the power of each individual lamp due to a corresponding increase in their number

Reflected gloss

Occurs when the reflection coefficients of surfaces falling into the field of view are high. The greatest danger arises when illuminating surfaces that are not diffuse, when the light falls on the working surfaces in such a way that the eyes are in the direction of specular reflection of the rays. In this case, a person sees either a mirror reflection of the light source or a blurry but very bright spot of light. In both cases, a state of blindness may occur, but more often the effective contrast between the detail and the background is reduced. Elimination of reflected glare is achieved by the correct organization of localized lighting and the arrangement of lamps so that the rays specularly reflected by the surface do not enter the eyes. To do this, it is best to do the lateral or posterolateral direction of the light.

Contrast between subject and background

The brighter the object, the greater the light flux from it enters the eye and the stronger the signal coming from the eye to the visual center. Thus, it would seem that the greater the brightness, the better a person sees the object. However, this is not quite true. If the surface (background) on which the object is located has a brightness close to the object (for example, a pale yellow line on a white sheet), then the intensity of illumination of the retinal areas by the light flux coming from the background and the object is the same (or slightly different ), the magnitude of the signals entering the brain is the same, and the object against the background becomes indistinguishable.

For an object to be clearly visible, the brightness of the object and the background must be different. The difference between the brightness of the object and the background, divided by the brightness of the background, is called contrast. The contrast between details and background, which most determines the visibility of an object, is not always given and can be increased or decreased by means of lighting and the creation of a light environment. One effective means of increasing contrast is an artificial background (usually light if the subject is dark, or dark if the subject is light). A variety of artificial backgrounds are light tables, on which surfaces are viewed in transmitted light.

Shadows

A distinction is made between intrinsic shadows formed by the surface topography and shadows falling from objects located outside the working surface - equipment, furniture, human body and hands, etc. In most cases, intrinsic shadows are useful because they allow you to better distinguish the configuration of a part. Falling shadows are almost always harmful. Their harm lies in the fact that they distort contrast, distract attention, etc. Moving shadows are especially harmful. Eliminating or limiting harmful shadows is achieved by choosing the correct direction of light. For example, when a person writes with his right hand, he looks at the working point on the left and the light should fall from the same side. Shadows blur as the size of lighting installations increases, soften when the brightness of walls and ceilings is high enough, and almost disappear with indirect lighting.

Saturation of the room with light

To create comfortable visual conditions for a person, it is important not only the illumination of any surface on which work is carried out, but also the impression that a person receives of the saturation of the room with light. Even if the working surface is sufficiently bright, the simultaneous presence of dark surfaces in the field of vision (for example, walls, ceilings, furniture, equipment) creates difficulties in adapting vision. The brightness of these surfaces determines the impression of light saturation in the room. If the room has direct light pendant lights, the upper area of ​​the room will remain dark. This produces an unpleasant aesthetic and psychological impression. Therefore, it is better to use light colors for walls and ceilings, and for lighting use lamps that emit some (preferably at least 15%) part of the light flux into the upper hemisphere.

Consistency of illumination over time

Changes in illumination over time can be divided into slow and smooth, frequent fluctuations and pulsations. Slow changes are caused by gradual changes in the mains voltage and factors that change the illumination during operation (pollution of light sources, decreased light output, etc.). If the illumination remains at a level not lower than the standard value, these changes are not harmful. The reason for frequent fluctuations is the movement of lamps, their swinging by air movement (wind, draft, ventilation unit, etc.) and voltage fluctuations in the network generated by changes in load.

Ripple

Illumination pulsations are due to the low inertia of the radiation of gas-discharge lamps; the light flux pulsates with alternating current of industrial frequency (50 Hz) with a double frequency - 100 Hz. These pulsations are indistinguishable when observing a stationary surface with the eye, but are easily detected when examining moving objects. If, under pulsating lighting, you quickly wave a pencil against a contrasting background, the pencil acquires clearly visible contours. This phenomenon is called the stroboscopic effect - the phenomenon of distortion of the perception of moving or rotating objects of observation. A practical danger of the stroboscopic effect is that rotating parts of machinery may appear to be stationary, rotating at a slower speed than they actually are, or in the opposite direction. This may cause injury. However, pulsating illumination is also harmful when working with stationary surfaces, causing visual fatigue and headaches.

Peripheral vision is most sensitive to pulsations and therefore they are dangerous in general lighting. An unfavorable effect of light fluctuations on the photoreceptor elements of the retina, as well as on the functional state of the nervous system, was also revealed, which is associated with the development of inhibitory processes and a decrease in the lability of nervous processes. The impact of pulsation increases with increasing depth and decreases with increasing frequency. Most researchers note the negative impact of pulsating illumination on human performance, both during long-term exposure to pulsating lighting conditions and during short-term exposure.

Limitation of ripple is achieved by alternating the supply of lamps from different phases of a three-phase network. In some cases, lamps are powered with high-frequency current, which is achieved by equipping lamps with electronic ballasts.

How to Convert Luxes to Lumens

However, if you know the required illumination value in lux and the area of ​​the illuminated surface, you can calculate the required luminous flux in lumens. It should be understood that the calculation will be performed with many assumptions, since it is not possible to bring the conditions for its implementation closer to physically ideal ones. When calculating, it should be assumed that:

• the light source is located in the center;
• the illumination is uniform over the entire area, which is practically impossible;
• light falls on the entire surface area at the same angle;
• the surface is illuminated from within the mental sphere supposed to surround the source.

In order to get the value in lumens, you need to multiply the standard in lux by the value of the area that needs lighting.

The floor and ceiling area will be: 10 x 10 = 100 m². Area of ​​each wall: 4 x 10 = 40 m². Theoretically, with the assumption of uniform illumination and the location of the source, equidistant from all points of the surface, the problem is solved as follows: 300 lux x (4 x 40 + 100 + 100) m² = 300 x 360 = 108,000 lm. If this astronomical value is “translated” into ordinary 100-watt incandescent lamps, then you will only need... 72 pieces.

The practical approach will be different. There is absolutely no need to illuminate the ceiling - employee workplaces are located below. Moreover, the design of many ceiling lights makes it impossible for light to spread upward. This means you need to remove the ceiling area from the calculations:

300 lux x 260 m² = 78,000 lumens.

Modern LED ceiling lights can produce 5,000 lumens. Accordingly, 16 pieces (78,000/5000) will be required, rounded to the nearest whole number.

This number can be reduced. According to SanPiN 2.2.1/2.1.1.1278-03, illumination is measured above the working surface, as well as at control points 1 m away from walls and light openings. It is enough to place lighting fixtures above employees’ workplaces. Mathematically reducing the geometric characteristics of the floor by 1 m on each side, we get:

300 lx x (160 + 64) m² = 300 x 224 = 67200 lm. What in the ceiling lights will be: 14 pieces, rounded to the nearest whole number.

Watch this video on YouTube

Features of measurements

Monitoring and evaluation of the listed lighting indicators is extremely important when providing comfortable conditions for living, learning or working. Measuring illumination is necessary when commissioning objects under construction, certifying workplaces, and inspecting educational and medical institutions.

Before carrying out control and measurement activities, specialists collect data on the characteristics of lighting in the object under study:

• establishing the presence/absence of natural light sources;
• type of artificial lighting system;
• condition of lighting equipment (design, completeness, contamination, etc.);
• number of non-working devices or lamps;
• condition of light openings.

The measurement of illumination parameters is carried out at the final stage of verification using precise measuring instruments that have passed metrological certification. Various configurations of measuring equipment can be used for assessment (the price of a lux meter often depends on the design and functionality of the device). Instruments with an error of no more than 10% are allowed for measurements.

Norms and calculation procedure

Lighting requirements depend on the purpose of a particular room and the type of human activity. The standards by which the indicator is measured are established in GOST R 54944-2012, the norms are in SNiP. All parameters apply not only to the floor, but also to the planes of the tables. Tables are available that can be used to determine lux for any property.

When developing a lighting system for a residential building (apartment), you can use the data from this table:

The calculation is carried out in 2 stages:

• determining the required level of luminescence;
• determining the number of light bulbs.

Formula for calculating the glow:

N*P*K, where:

N – norm (according to the table);

P – room area;

K – coefficient depending on the height of the ceilings (1 for 2.5-2.7 m, 1.2 for 2.7-3 m, 1.5 for 3-3.5 m, 2 for 3.5-4, 4 m).

To calculate the number of lamps, the result must be divided by the lumens indicated in the technical documentation of the lamps selected for installation.

If major repairs or reconstruction work is carried out, the contractor’s employees handle the calculations.

They take into account the design features and materials of lamps, light reflection from walls, floors, ceilings, and interior items, depending on the characteristics of the facing material. The type of lamps is preliminarily indicated in the design documentation and technical specifications.

The formula used for calculations is:

K=(E*k*S*k1)/(F*k2), where:

E – norm for horizontally located planes;

k – coefficient calculated taking into account deviations in the operation of the system when individual light sources burn out and interior items move;

S – area of ​​the room;

k1 – coefficient of unevenness;

Ф – luminous flux from one light bulb (depending on power and type);

k2 – coefficient in shares.

When carrying out measurements and calculations yourself, it should be taken into account that reflected light in power may differ little from direct light.

Systems and types of industrial lighting

Based on the light source, natural and artificial lighting are distinguished. For the human eye, the most valuable is natural light caused by natural sources (rays of the sun, light from the sky). Vision is biologically best adapted to this type of lighting. To obtain natural light, windows are used in the external walls of buildings (side lighting), transparent structures on roofs (top lighting) or a combination of these two options (combined lighting). Without natural light, work can be carried out in special premises, as well as basements and basement rooms of buildings (only for permitted types of use).

When there is a shortage of natural light, artificial lamps are used. They are used in the evening and at night in rooms where there are no natural sources. Combined lighting combines natural and artificial light sources.

In industry, 4 types of artificial electric lighting are provided:

Working lighting ensures the fulfillment of the main tasks of work activity. It is equipped with all production workshops, auxiliary premises, and corridors in which work and passage of people are provided. If sections of a building or workshop have different degrees of natural light, different work modes, the adjustment of working lighting should be divided into zones. There are general and local lighting. In the upper part of the room there are general lighting fixtures, which ensures uniform visibility of all areas. Local lighting is used for a specific workplace and is necessary for high-precision work. With combined light, general-purpose lamps must cover at least 10% of the illumination of the working surface. Requirements for local sources: not to be in the field of view of employees, have non-transparent reflectors.

Emergency light sources are necessary to find escape routes in the event of an emergency or to continue work when it is impossible to stop production. These lamps are installed if there is a possibility of the main light being turned off under extraordinary circumstances. Emergency lighting ensures the safety of people in the event of unforeseen situations.

Calculation of luminous flux

In order to understand the required luminous flux parameter and calculate the number of LED lamps in the room, it is necessary to multiply the standard sanpin indicator by the area of ​​the room and the coefficient taking into account the ceiling height (for a ceiling of 2.7 meters it is 1, and for 3 meters it is 1.2). As a result, it turns out that 150 lux are needed to illuminate the kitchen and bedroom, 350 lux for the office, and 50 lux for the bathroom and hallway.

Further, when calculating, you should rely on the power of the light sources, expressed in lumens. The resulting value according to the formula should be divided by the power of the lamps and their number will be obtained.

Note! To correctly calculate the power of the luminous flux, you need to use the formula for the ratio of specific power per room area, divided by the number of lamps. How to calculate light flux using the formula

How to calculate light flux using the formula

Measuring the amount of light for LED devices and examples in nature

LED lamps have become very popular due to their unique energy efficiency. But LEDs and their power supplies emit heat when illuminated, which is dissipated using heat-conducting materials (aluminum) and design features (fins, large radiator area). Despite the apparent lack of connection between heat loss and illumination, experts always take it into account when creating new devices.

Difficulties with the operation of LED lamps begin when operating in conditions where the temperature rises above +50°C. Why is it recommended to measure the illumination of LEDs after 2 hours of their operation, i.e., after reaching the optimal mode. To eliminate the occurrence of errors, repeated measurements are taken during the work shift. It is advisable to carry out these studies at least once a year. In order to eliminate any errors during design, a light reduction coefficient is set, depending on the physical characteristics of the object.

Office lighting with LED lamps

Typically, manufacturers of LED devices provide a guarantee of their flawless operation for 3 years. All operating parameters of such lamps, including illumination, must correspond to the declared values. If the operating conditions of the devices occur at outdoor temperatures above 45°C, then light measurements must be taken much more often. Otherwise, incorrect design and the results obtained will lead to a rapid drop in lighting performance.

As for examples of illumination in nature, in the Earth’s orbit and the equator at noon this value is equal to 135 thousand lux. On a sunny day it is up to 100 thousand lux, on a cloudy day it is only 1 thousand lux, but from the Moon it is only 0.2 lux. Measurement of light on the street at the latitude of Moscow in winter showed from 4 to 5 thousand lux. On a moonless night, the illumination is a thousand times less than on a full moon, and with 10-point cloudiness it is 10 thousand times less. What illuminance is measured in indoors and outdoors refers to the physical quantities included in the International System of Units.

How is the degree of illumination measured?

As we have already found out, the unit of illumination is Lux. It’s easy to guess the name of the device used to measure light levels. “Lux” plus “meter” (translated from ancient Greek as “measure”, “meter”) equals luxmeter. The operating principle of this portable device is similar to that of a photometer.

The light flux incident on the element releases electrons in the body of the semiconductor, due to which electric current begins to be conducted by the photocell. The magnitude of the electric current is directly proportional to the degree of illumination of the photocell, which is displayed on the scale or on the electronic display, if this is a modern model of luxmeter. Analog devices are equipped with a special scale with degrees. The movement of the arrow determines the final measurement results.

Digital devices.

Analogue lux meters have been replaced by digital ones - small computers. The parameters can be seen on a small LCD screen. The part that measures light is often contained in an outer casing and connected to the main device by a flexible wire. Because of this design, it is possible to measure lighting in any place, even hard-to-reach places. According to GOST, the device error should not exceed 10 percent.

Important points.

When calculating comparative light intensity, you can measure the light intensity with an analog or digital device. Modern meters display parameters in lux, while outdated analog meters—those with an arrow—in footcandles. 1 foot-candle equals 10.76 lux.

Indoor illumination

In nominal terms, it is the flux of light that is emitted onto a surface at right angles per unit area. When light falls at an acute angle, the illumination decreases depending on the angle of inclination.

Illumination is measured in lux, which is equal to 1 lumen (unit of luminous flux) per m2.

The illumination of the premises directly depends on the strength of the light that comes from the source. The greater the distance from the light source to the surface, the lower the illumination parameter.

Norms

Each type of room has its own lighting standards. For example, for a grocery store, the highest pulsation value is set at 15%, illumination at 300 lux, but for a sporting goods or building materials department, the standards are completely different. The rules also establish certain permissible illumination for clinics, kindergartens, car services and other facilities.

Example of illumination calculation

Let's determine the required lighting for the bedroom. The bedroom area is 25 m2. The value of the norm according to the rules for rooms of this type is multiplied by the area: 150 x 22 = 3300 lux. The total luminous flux of lighting devices at this level of illumination must be at least 3300 lumens.

Now all that remains is to choose the right lighting lamps for the bedroom. When choosing LED lamps, you can, for example, purchase three such lamps of 12 watts each. This will ensure the creation of a luminous flux of 3600 lumens, as can be seen from the table values.

This calculation is approximate, since LED lamps have different light parameters depending on the manufacturer. Thus, you can easily independently calculate the required power and type of lamps to create standardized illumination of any room in accordance with the rules of SNiP.

Instruments for measuring illumination

To measure room illumination, various devices are used, which have their own design features and measurement methods. Let's look at the main devices in more detail.

Luxmeter

Lux meters are divided into electronic and analog, which are no longer produced, and only old samples of such models remain.

This lux meter is used:

• Checking compliance of room illumination with regulatory data.
• Measuring lighting parameters when carrying out work to assess working conditions.
• During electrical installation work to compare illumination indicators with calculations for lighting devices.

The principle of operation of a lux meter is based on the operation of a built-in photocell, onto which a stream of light is directed. In this case, a significant flow of charged particles appears in the photocell. As a result, a flow of electric current appears, the strength of which depends on the strength of the light flux directed at the photocell. Usually this parameter is displayed on the instrument scale.

Types of lux meters

Depending on the location of the sensor that measures room illumination, lux meters are divided into types:

• A device with a remote sensor connected by a flexible wire.

To make simple measurements, a regular monoblock lux meter is suitable, without various auxiliary functions. To determine several illumination parameters when performing professional calculations, it is necessary to use devices that have an additional set of functions. Such devices have built-in memory and can determine average parameter values.

Luminous flux measurement

Before releasing a product to the market, the manufacturer determines and measures the characteristics of the lighting device in the laboratory. It is impossible to do this at home, without special equipment. But you can check the numbers indicated by the manufacturer using the above formulas using a compact lux meter.

The difficulty in accurately measuring light is that it comes from all possible directions of propagation. Therefore, laboratories use spheres with an inner surface that has a high reflectivity - spherical photometers; They are also used to measure the dynamic range of cameras, i.e. photosensitivity of their matrices.

In everyday life, it makes more sense to measure such important light parameters as room illumination and pulsation coefficient. High pulsation ratio and dim lighting cause people to overstrain their eyes, which causes fatigue faster.

The light flux pulsation coefficient is an indicator characterizing the degree of its unevenness. Acceptable levels of these coefficients are regulated by SanPiN.

It is not always possible to notice with the naked eye that the light bulb is flickering. However, even a slight excess of the pulsation coefficient affects the human central nervous system negatively and also reduces performance. Light, which can pulsate unevenly, is emitted by all screens: computer and laptop monitors, tablet and mobile phone displays, and TV screens. Ripple is measured with a lux meter-pulse meter.

Residential lighting standards

The illumination of rooms for different purposes is not the same and can vary by an order of magnitude. The number of lumens per square meter by type of residential premises is as follows:

• office, library, workshop - 300;
• children's room - 200;
• kitchen, bedroom - 150;
• bathhouse, sauna, swimming pool - 100;
• wardrobe, corridor - 75;
• hall, corridor, bathroom, toilet - 50;
• staircase, basement, attic - 20.

Calculation of illumination for premises

To determine the illumination of a room, you need to know the following parameters:

1. E - standard value of illumination (how many lumens are needed per 1 m²).
2. S is the area of ​​the room.
3. k - height coefficient:
   k = 1 with a ceiling height of 2.5 - 2.7 m;
4. k = 1.2 with a ceiling height of 2.7 - 3.0 m;
5. k = 1.5 with a ceiling height of 3.0 - 3.5 m;
6. k = 2 with a ceiling height of 3.5 - 4.5 m;

The formula for calculation is simple:

Ф = E•S•k.

Knowing the illumination, you can select the required luminous flux and power of lighting lamps, taking into account their differences in production technologies and operating principles. One should take into account the peculiarities of human vision, for whom light sources with a bluish tint (from a color temperature of 4700K and above) seem less bright.

Watch this video on YouTube

Illuminance measurement range

A special device for measuring illumination, a lux meter, is selected taking into account the intended working area. There is no point in wasting energy resources unnecessarily. Professional calculations are carried out taking into account the specifics of individual operations: from general observation to actions with small details of the highest precision.

Standard illumination of objects

The sensitivity of the human eye to certain parts of the spectrum is essential. Modern instruments for measuring light are created taking into account the corresponding features. Usually the visible range is checked. However, we must remember that imperceptible ultraviolet radiation at high intensity has a negative effect on the retina.

Also check ripples with a frequency of up to 300 Hz. They are visible to human vision. Such changes in the amplitude of radiation cause discomfort, even pain. It is necessary to remember the dangers of excess lighting. In such conditions, the overall load increases significantly, as metabolic processes in the body are activated.

Interesting. Separate mention should be made of plant care. Illumination for roses and palm trees is set above 14,000-16,000 lux. For unpretentious ficuses, 8,000-11,000 lux is enough.

Lighting control makes it possible to obtain good year-round yields at reasonable energy costs.

Lighting required per 1 m2

Lighting power is an important indicator, which is measured in lux and lumens, which is a subunit of lux. Without properly selected lighting, it is impossible to have a comfortable rest and stay in any room. Different types of rooms require their own calculations. They can be produced taking into account the number of light sources and sanitary standards for one square meter.

Unit

When answering the question of how many units are required to illuminate one square meter and how to calculate the illumination of a room with LED lamps, you should understand the purpose of a particular room. For example, a bedroom requires 100 lumens per square meter, and a bathroom requires 150.

As a rule, all technical lighting standards are given in regulatory documents in lux. If necessary, they can be converted to lumens.

How many lumens do you need for one square meter?

Calculation errors

When calculating lighting, it is important to understand that with a change in the color of wall and floor coverings, a change in the suspended or suspended ceiling with its reflective ability, the light flow changes. It is important to know the reflectance of each color

Thus, white surfaces can reflect up to 70% of light, gray surfaces 30%, and black surfaces 0%. It is also worth noting that many people make mistakes with the color of light bulbs, since the color of the light sources themselves affects their throughput and power.

Soviet standards and snips are often used in calculations, but you need to understand that they were developed at a time when modern light sources had not yet been invented. There was also no special concern about what room a person needed to be in.

Note! An error often occurs when calculating lighting when combining different light sources, colors and overall texture. Often an excessive amount of lighting equipment leads to a lighting surplus

This is just as bad as a deficiency for the eyes and general well-being of the people who will be in this room.

Dependence of illumination on lamp color

Illumination is a quantity that is equal to the light flux of an area of ​​the illuminated surface. It is measured in lux, which is equal to one lumen per square meter. You can understand how many lumens per square meter you need based on the distance, length and width of the room, as well as the power of the lighting devices.

It is important to understand that today there are certain sanitary lighting standards. They must be strictly followed to ensure the well-being of the people in the room.

To correctly calculate the required number of light sources and lumens, you can use the formula presented above or an online calculator.

Requirements for lighting of industrial premises

Regulatory acts contain the following basic requirements for industrial lighting:

• the illumination of the premises is distributed evenly;
• lighting standards for a specific type of work are met;
• the functioning of light sources is stable;
• general lighting of work activity areas is more intense than local lighting;
• corridors and production areas where no work is being done are illuminated by more than 25% of the general light standards and not less than 100 lux;
• there are no sharp shadows from lamps;
• luminous elements of local sources are not in the field of view of employees;
• local lamps are equipped with opaque reflectors.

Particular importance is attached to life safety when using lighting devices:

• The use of incandescent lamps with a power of 100 W or more is prohibited;
• color temperature of luminaires is allowed in the range from 2400°K to 6800°K;
• ultraviolet waves with a length of 320–400 nm cannot be more intense than 0.03 W/m², the presence of ultraviolet with a wavelength of less than 320 nm is prohibited.

Lumen and Watt

Energy-saving lamps with the same light output consume 5-6 times less electrical energy than incandescent lamps. LED – 10-12 times less. The power of the light flux no longer depends on the number of watts. But manufacturers always indicate watts, since the use of too powerful light bulbs in sockets not intended for such a load leads to damage to electrical appliances or a short circuit.

If you arrange the most common types of light bulbs in order of increasing light output, you can get the following list:

1. Incandescent lamp – 10 lumens/watt.
2. Halogen – 20 lumens/watt.
3. Mercury – 60 lumens/watt.
4. Energy saving – 65 lumens/watt.
5. Compact fluorescent lamp - 80 lumens/watt.
6. Metal halide - 90 lumens/watt.
7. Light-emitting diode (LED) – 120 lumens/watt.

But most people are accustomed to looking at the number of watts specified by the manufacturer when purchasing light bulbs. To calculate how many watts per square meter you need, you first need to decide how bright the light in the room should be. 20 watts of incandescent lamp per 1 m² - this lighting is suitable for a workplace or living room; for a bedroom 10-12 watts per 1 m² will be enough. When purchasing energy-saving lamps, these numbers are divided by 5

It is also important to take into account the height of the ceiling: if it is higher than 3 m, the total number of watts should be multiplied by 1.5

Lighting of industrial premises

To perform most work, a person needs light. Low lighting leads to a decrease in the quality of work, an increase in the percentage of defects, causes depression in workers and reduces their productivity. According to research by the International Commission on Illumination, with well-organized lighting in the workplace, labor efficiency increases by 10%. All this led to the identification of industrial lighting into a special type, aimed at creating the best light conditions for the implementation of labor functions.

How to measure light brightness

You can measure brightness using a specialized device. In a high-quality brightness meter the following is installed:

• high aperture lens;
• sensitive matrix;
• microprocessor information processing/output unit.

If such a device is well configured, it will be able to measure the intensity of light at a great distance from the source (reflective surface).

Luxometer

Devices in this category are created with a built-in or remote sensor. The simplest pointer instruments are inexpensive. However, they are inconvenient to use in hard-to-reach places and at high levels of vibration. Digital models provide increased accuracy. A photosensitive sensor is installed on the surface. After processing, the measurement result is displayed on the display and recorded in memory.

Lighting standards for different rooms

It is necessary to ensure normal illumination of premises to maintain human health, which is regulated by standards.

The standards for artificial lighting with fluorescent lamps are given below.

Important! For regions of the north and polar stations there are their own norms and standards. Thus, special “full spectrum lamps” are produced, which partially compensate for the lack of exposure to the sun with an acceptable amount of UV

Accepted interpretations when determining illumination intensity:

• SI – System of units of physical quantities;
• IR – Infrared radiation;
• UV – Ultraviolet radiation;
• nm – nanometer (1/10*9 m);
• THz – Terahertz (1x10*12 Hz).

Having studied the nature of light, from candles to lasers, using electricity, scientists control the diverse work of radiation. But people tend to radiate their energy and emotions, thoughts and feelings, goodness and joy. The French scientist Pascal said it well: “There is enough light for those who want to see, and enough darkness for those who do not want to.

Features of artificial lighting

Artificial light sources are characterized by increased pulsation, which can adversely affect human health and vital activity. Pulsating light affects the visual apparatus and nervous system, provokes irritability, chronic diseases, and frequent headaches. To standardize artificial lighting, a pulsation coefficient is used. Calculation of this coefficient is necessary when assessing the depth of illumination fluctuations over a certain period of time. For the light pulsation indicator, acceptable norm limits have been established, which depend on the type and purpose of the room. For example, for children's educational institutions, an indicator of no more than 10% is acceptable, for offices equipped with computers - no more than 5%. Assessing light pulsation also requires the use of a professional lux meter.

The power of light

It would be more logical to call the unit of luminous intensity

angular luminous flux. Luminous intensity - candela (lm/sr), cd -
candela
, Kd, ​​“candle”, lumens divided by steradian. Light intensity is also called candlepower. It is interesting that in ancient times a 60-watt light bulb was often called a 60-candle light bulb, but it did not give 60 cd of light.

If you place a reflector on one side of the light bulb spiral, dividing the sphere in half, the light intensity will increase by 2 times. For example, a household matte krypton incandescent lamp under the General Electric brand 75W 230V produces a luminous flux of 865 lumens. A concave mirror dividing the sphere in half will increase the light intensity by 2 times. A mirror in the shape of a paraboloid around a light bulb will increase the light intensity to infinity, which, of course, is impossible due to its non-infinitesimal size.

But it is possible to increase the brightness of the light source-mirror to infinity at the focus of the optical system. In practice, it is impossible to achieve complete infinity, but it is possible to melt gold.

An example of expressing brightness (lm) in terms of luminous intensity (Cd)

Given: LED (light source) luminous intensity (lum. intensity) 110 mcd (mcd) in angle (viewing angle) 130°. ———————————Find: “total luminous intensity” (as if by all directions), correct - luminous flux

in lumens from a given light source.

Please note: the plane section of the volumetric cone (viewing angle) is given in FLAT DEGREES. You can follow a simplified path: “translate” flat degrees (in this interpretation) into “correct” volumetric steradians through the relation (1).130° (“flat degrees”) ≈ 2 sr (“volume steradians”)

You can follow a simplified path: “translate” flat degrees (in this interpretation) into “correct” volumetric steradians through the relation (1).130° (“flat degrees”) ≈ 2 sr (“volume steradians”)

And lumens (luminous flux) is cd⋅sr, substituting the values: 110 mCd × 2 sr = 220 mLm = 0.22 Lm.

Not bright, however! (Compare incandescent bulbs.) But you need to check the price of the LED! May be cheaper than one high-power LED. (Or maybe not.)

Instruments for measuring light levels

The device that measures light levels is called a lux meter. It can be analog or digital.

The luminous flux falls on the photocell, releasing electrons, which causes the conduction of current. Its value, which is reflected on the scale (graduated in lux), is proportional to the illumination level of the photocell. If the lux meter is analog, the result is visible by the deflection of the arrow.

In digital lux meters, the result is visible on the LCD display. Most of them have a separate part that measures the indicator, connected to the display using a wire, and the measurement limits are adjustable. This design makes it possible to measure illumination in places inaccessible to an analog lux meter.

Photographers use more precise equipment:

• exposure meters (measure exposure illumination);
• flash meters (used together with photo flashes);
• photometers (combines the characteristics of a flash meter and an exposure meter).

When choosing light bulbs for lamps, you should not focus on one indicator. The luminous flux has many characteristics; recently, one of the most important is the pulsation coefficient.

There are instruments that allow you to simultaneously measure illumination, brightness and pulsation. They are called a lux meter-heart rate monitor-brightness meter. The light is captured by a photocell and the result is visible on the display. To determine the ripple coefficient, the data is processed by a special program installed on the computer.

Illumination concept

Illumination is an indicator that is measured as the ratio of the amount of light flux to a unit area onto which it falls perpendicularly.

When making calculations, it is necessary to take into account that illumination:

• directly proportional to the strength of the luminous flux;
• inversely proportional to the square of the distance from the source to the illuminated area;
• is directly proportional to the cosine of the angle at which the light flux falls.

Lighting can be:

• natural – penetrates into premises through openings of supporting structures;
• artificial – created by lighting devices;
• combined – natural, supplemented with artificial.

In a room, you can arrange a general (most often ceiling), local (supplying light to individual zones), combined (general, supplemented by local) lighting system.

Recommendations for light measurements

The level of natural and artificial light is measured separately. Be sure to place the lux meter in a horizontal position. The points at which the indicator is measured are determined by state standards. In practice, those that are not located near sources of electromagnetic radiation are used. It is also important that no shadow falls on the lux meter.

At the end of the measurements, the obtained data is checked against the standard ones in order to assess the conditions in a particular room.

Important! If the coefficient is measured in rooms with an existing lighting system, you must wait approximately 1-2 hours for the lighting fixtures to work. More accurate data can be obtained if the indicator is measured several times during one day.

Calculation of the number of LED lamps for a room

According to the previous information, you can find out the number of LED lamps by calculating the light flux and dividing it by the power of the lamps. For example, for a kitchen with an area of ​​20 square meters and a ceiling height of 3 meters, where it is planned to install LED chandeliers or lighting of 900 lumens, 4 lighting fixtures using counting technology are needed.

In the calculation example, it is worth indicating that the calculations were made as follows: (150 lux lighting standards for the kitchen * 20 square meters * 1.2 ceiling coefficient) / 900 lumens. You can also calculate the required number of light sources using special online calculators on the Internet.

Required number of LED lamps for the room

How to correctly measure illumination in different rooms

Regardless of the type of room, measurements should be carried out only with special instruments. You can evaluate the characteristics without a lux meter (with a camera or phone), but high-quality measurements are only possible with the use of special equipment. Before starting the measurement itself, it is necessary to replace all failed lighting fixtures and lamps so that their parameters correspond to the factory standard. This is typical for measurements in production facilities and workplaces, subject to OHS conditions.

Most often, measurements are made with a lux meter, which helps to assess the quality of light and general working and living conditions, or to create such parameters in the future. The measuring process is as follows:

• The device is placed in a horizontal position, directed to the measurement point (installed on the table in close proximity to the light source being measured);
• If possible, a photographic sensor is pointed towards the light source;
• If the device indicator shows. When measurement is possible, its toggle switch switches to the appropriate mode;
• The result recorded on the display is analyzed by comparison with standard indicators.

Important! The device records the amount of light and its rays that fall on its photosensitive element and, accordingly, on the desktop or other surface. If you need to obtain data from some isolated lighting device, then all other sources must be turned off

Correct measurement

What is lighting

Light is a type of electromagnetic vibrational motion. It differs from radio and electrical waves in that their length is much shorter. Particles (quanta and photons) emit these light streams in portions. When they hit the human eye, the optic nerve converts them into sensations (brightness and color, converted into an image).

General room lighting

There are two types of lighting:

• Natural, the source of which is radiation from the Sun;
• Artificial, produced by various special devices and installations.

These types of lighting are combined, and many other classifications are created based on them. Among the most famous of them are the following:

• General – creates a level of illumination sufficient for a person to stay comfortably in the room;
• Zonal - affecting a specific area (zone) of the room and providing an increased level of light in it;
• Local – designed to highlight an object and the space around it (keyboard, reading space, desktop);
• Decorative - has become popular relatively recently and is used to decorate certain interior solutions and to increase comfort;
• Emergency - switched on in production and enterprises during an emergency when conventional electrical installations cease to function normally.

You may be interested in Determining the power of a resistor
Important! In turn, these types can be divided into other, smaller categories depending on functional features and requirements.

Example of emergency lighting