Disinsection
What characterizes keo. Natural room lighting

What characterizes keo. Natural room lighting

Population movements

The simplest indicators of the natural movement of the population - the general coefficients - are so called because when they calculate the number of demographic events: births, deaths, etc. are related to the total population. Since these coefficients are very similar to each other and are built according to a single actual method, it seems convenient to single out their description in a separate chapter.

But first, let's talk about demographics. All indicators can be divided into two main types: absolute and relative. Absolute indicators (or values) are simply the sums of demographic events: (phenomena) at a point in time or in a time interval (most often for a year). These include, for example, the population on a certain date, the number of births, deaths, etc. for a year, a month, several years, etc.

Absolute indicators in themselves are not informative; they are usually used in analytical work only as initial data (raw materials) for calculating relative indicators. They are not suitable for comparative analysis, because their value depends on the population, with which they are always in a certain proportion, or in other words: which produces them. For example, it is impossible to say: "The death rate has decreased by 200 thousand people." The decrease in the number of deaths may be the result of a reduction in the total population or its structural changes. Another example: if, say, in 1995, 12,000 children were born in the Republic of Buryatia, and 6,000 in the Republic of Tyva, it cannot be said that the birth rate in Buryatia is twice as high as in Tuva. After all, the population of Buryatia is 3.4 times larger than that of Tuva. Only by comparing the number of events with the size of the population producing these events, it is possible to determine the comparable intensity of a given phenomenon or process for each of the compared republics, and bring them to a comparable form. In the case of comparing Buryatia and Tuva, then it turns out that the birth rate higher in Tyva, not in Buryatia, and 1.7 times.

For comparative analysis, for comparisons of any kind, whether statically or dynamically, one should use only relative figures. They are called relative because they always represent a fraction, a relation to the population that produces them, and thus the difference in population is eliminated (eliminated). The main requirement of any comparison of any two (or several) features is to equalize all other features of the phenomenon under study, except for those that are directly compared. Only then can one get an idea of the actual difference between the studied traits. Unfortunately, the reduction of the studied phenomena to a comparable form, the elimination of all factors extraneous for this comparison is a task as frequent as it is difficult. In the social sciences, this task is often not solved adequately (because of the difficulty of isolating the object of observation in its “pure form” from the general mass of social phenomena. This can, as a rule, be done only with the help of mental abstraction, and this is the danger of an inadequate representation about the phenomenon being studied).

In turn, relative indicators can be divided into two main types: probabilities and coefficients. Probability, as is known from probability theory, is the ratio of the number of events that have occurred to the number possible. In this case, of course, the accomplished and possible events must refer to the same kind (class) of phenomena. Usually, when calculating probabilities, the number of events that have occurred, say the number of births during the year, is correlated with the number of women at the beginning of this year. Then the quotient will show the probability of having a given number of children when all the conditions under which the probability calculation is made are repeated.

However, in the composition of the population it is not always possible to single out with sufficient clarity the totality of the population that produces a given demographic event. More often it is necessary to correlate demographic events with a population that is heterogeneous in its structure (aggregate, as statisticians say), which simultaneously includes people for whom the studied demographic event is possible with a certain probability, and those for whom it is impossible, but they cannot be excluded from the calculation. This is where coefficients differ from probabilities. In practice, it is more often necessary to use coefficients for quite obvious reasons. Correlating interval indicators (the number of demographic events during a period of time) with the average population for this period of time, they are thus brought into line with momentary indicators (population).

The average population in relation to a certain period of time (more often - to a calendar year) is calculated quite simply. Assuming uniform population growth throughout the year, the average (average annual) population can be calculated as half the sum of the population at the beginning and end of the year for which the desired average is calculated. Or this average annual population can be represented as half the sum of the populations at the beginning of the year for which this average is calculated, and at the beginning of the next year, which will give the same result as in the first option (since the populations at the end of the year and at the beginning of the next practically coincide ).

The calculation can be represented as a formula:

where is the average annual population (in the reference year " t»); P t - population at the beginning of the accounting year " t»; P t +1 - population at the beginning of the next year, i.e. t + 1.

Now let's look at the formulas by which the general coefficients of natural movement of the population are calculated. First, let's introduce symbols, using letters of the Latin and Russian alphabets interspersed (unfortunately, the notation, i.e. the designation of conventional signs in formulas, has not yet been fully standardized in demography. Therefore, authors all over the world use the notation that seems most suitable to them) . We will treat the letters used not as letters of the national alphabet, but as completely conventional signs. The general principle is as follows: capital letters indicate absolute indicators, lowercase letters - relative. From here N- the number of births in the billing period (usually a calendar year, but it can be half a year, quarter, month, several years), may be with upper and lower indices indicating additional information (age of mothers, their marital status, etc.); respectively P - total fertility rate; M- the number of deaths in the billing period; T - crude mortality rate; EP- natural increase, defined as the difference between the number of births and deaths, a k EP - coefficient of natural increase; IN(Latin) - the number of marriages, and b- total marriage rate; D- number of divorces d- overall divorce rate. Suffixes - “bridge”, - “nost” in the words "fertility", "mortality", etc. indicate the intensity of these categories. Total population designation - R- we already know. Let's add to this T - the length of the calculation period in whole years - and we can now write the formulas mathematically.

Total Fertility Rate:

Crude death rate:

General coefficient of natural increase:

Total marriage rate:

General divorce rate:

When calculating coefficients for one calendar year T = 1 and, of course, goes down. Since the quotient of dividing the number of vital events by the size of the population is a very small value, it is multiplied by 1000 (i.e., thus expressing the number of vital events per 1000 population). As a result, we get an indicator, expressed in ppm, from lat. pro mille- by 1000 (a unit, ten times less than the percentage more familiar to us). It is denoted by the ppm symbol ‰, in which, unfortunately, one of the zeros at the bottom is often ignored by typists who stubbornly type (in cases where the author's manuscript is retyped on typewriters, and not on a computer) percentages instead of ppm, plunging the authors into a state of shock when they subsequently see their work of genius published. Meanwhile, it must be said, the ppm sign is also easily printed on a typewriter by adding a lowercase letter "o" to the percent sign. So the printing of the sign per mille is a problem of performing culture, not technical capabilities.

General vital statistics are calculated with standard accuracy up to tenths of a per mille, or with one decimal place after the decimal point. Sometimes students represent the coefficients with eight decimal places, sometimes, on the contrary, they are in whole numbers. Both that, and another - from negligence, or rather, from a lack of experience. Neither excessive precision nor coarse rounding of the coefficient value is needed. At the same time, it is important to keep in mind that zero as part of the coefficient is not an extra figure at all, which can not be shown. In fairness, it must be said that vital numbers in whole numbers can be found not only in student papers, but also in quite “adult” publications in newspapers and even scientific journals.

Let's consider an example of calculation of the general coefficients of natural movement of the population.

The population of Russia at the beginning of 1995 amounted to 148,306.1 thousand people, at the beginning of 1996 - 147,976.4 thousand people. In 1995, 1,363.8 thousand people were born in the country, 2,203.8 thousand people died. It is required from these data to determine the general birth rate, death rate, natural increase in absolute terms and the total rate of natural increase.

First, the average annual population for 1995 is calculated.

Thousand Human.

total fertility rate ‰.

Crude death rate ‰.

Now you can determine the total rate of natural increase

I especially draw attention to the fact that the natural increase and the coefficient of natural increase are algebraic quantities, i.e. can be either positive or negative. In this case, the sign is negative, showing that the population of our country is not growing, but decreasing.

On the basis of data on the population and its natural movement, it is possible to calculate the volume migratory growth population. For this, the relationship between overall growth population (the difference between the population at the beginning of the period under study and the population at the end of the same period or at the beginning of the next period, which is the same), natural increase and migration increase population (which is defined as the difference between the number of migrants who arrived in the study area and those who left it). This relationship can be represented as a formula:

OP= EP + MP,

Where OP- total population growth; EP- natural population growth; MP - migratory population growth.

By analogy with the coefficient of natural increase, it is possible to calculate the coefficients of general and migration growth (K OP And K MP).

Let us now calculate the total and migration growth of the population and the coefficients of the total and migration growth of the population of Russia for 1995.

General gain

OP \u003d P t +1 - P t \u003d 147976,4 - 148306,1 = - 329.7 thousand people.

natural increase

EP= N-M= 1363,8 - 2203,8 = - 840.0 thousand people.

And finally, migration

MP = OP- EP =(- )329,7 - (- )840.0 = 510.3 thousand people.

‰

Let's summarize. The population of Russia in 1995 decreased in relative terms by 5.7‰ due to negative natural growth, but increased by 3.5‰ due to positive migration growth. As a result of the opposite effect on the total population growth of differently directed natural and migration increases, the total population growth in Russia in 1995 amounted to a negative value of 2.2‰.

The general coefficients of natural movement of the population have certain dignity and even bigger flaws. Advantages the following:

1) eliminate differences in population size (since they are calculated per 1000 inhabitants) and thus make it possible to compare the levels of demographic processes of territories with different populations;

2) one number characterizes the state of a complex demographic phenomenon or process, i.e. have a general character;

3) very easy to calculate;

4) for their calculation in official statistical publications almost always there are initial data;

5) are easily accessible to the understanding of any person, even a little familiar with the methods of demographic analysis (therefore, probably, from a wide range of demographic indicators, perhaps only these, the most rough in their simplicity, can sometimes be found in the media).

However, the common coefficients actually have one shortcoming, stemming from their very nature, which consists in the non-uniform structure of their denominator, as already mentioned above. Due to the heterogeneity of the composition of the population in the denominator of the fraction, when calculating the coefficients, their value turns out to depend not only on the level of the process that they are designed to reflect, but also on the characteristics of the population structure, primarily gender and age. Because of this dependence, it is almost never known, when comparing these coefficients, to what extent their value and the difference between them indicates the actual level of the process under study, the actual difference between the levels of the compared processes, and to what extent - about the features of the population structure. The same is true in the case of studying the dynamics of demographic processes. It is not known due to what factors the value of the coefficient changed: either due to a change in the process under study, or due to the structure of the population.

Take, for example, the total fertility rate, the ratio of the number of newborns to the total population. Three-quarters of this population, represented in the denominator of the fraction when calculating the coefficient, is not directly related to the birth of children that make up the numerator of the fraction. These are all men, who make up about half of the population, children - formally up to 15 years old, but in fact - until a more mature age, women - formally after reaching 50 years old, but in fact - already after 35 years old. And finally, the majority of unmarried women. If we take into account all these named categories of the population, it turns out that in order to fully match the numerator and denominator of the fraction when calculating the total fertility rate, it would be necessary to correlate the number of children born mainly only with the number of married women aged 20 to 35 years, who, in particular, say, according to the 1989 census, they accounted for only 9.0% of the total population (!). The remaining 91% of people, reflected in the denominator of the fraction when calculating the birth rate, were not directly related to its numerator. Meanwhile, depending on changes in the structure of this “non-parous” majority of the population, the value of the coefficient can vary greatly, misleading users about actual changes in the intensity of fertility.

When calculating the crude death rate, there does not seem to be such a problem. Sadly, everyone is subject to death. But... at different times. The probability of death varies greatly depending on age (we will not talk about other factors now). And, consequently, with a change in the age structure (and sex as well, since female mortality is lower than that of males in all age groups), the value of the total mortality rate will change, while the intensity of mortality in each age group may remain unchanged or even change in direction opposite to that in which the value of the mortality rate changes.

Such paradoxes are also possible. The marriage rate is the ratio of the number of people married in a given year to the average population. It is clear that the children that make up the denominator of the fraction when calculating the coefficient are present in it in vain until they reach the age of marriage. But adults, say married people, are also reflected in vain in the denominator of the fraction when calculating the marriage rate, since, obviously, they cannot marry, they are not marriageable. One can imagine such a hypothetical situation. In a population with a high level of marital status, i.e., in which the majority of the population is already married, the marriage rate will be low precisely because the number of unmarried people will become very small. There is no one to marry because the majority is already in it.

It's the same with divorce. In a hypothetical population where no one is married (for various reasons), there will be no divorces either.

As sources of information on population and demographic processes develop, interest in the use of general vital statistics is gradually decreasing. Some directories no longer even publish them. In the specialized literature, general birth and death rates are mainly used only to calculate the general rate of natural population growth based on them.

In demographics, there are now quite a few indicators that are more advanced than rough general coefficients. They need to be used. If, however, it is necessary, by virtue of necessity, to use general coefficients, one must strive to weaken their dependence on the distorting influence of the characteristics of the age (or any other) structure of the population. This can be achieved in many ways, described in reference books on general and mathematical statistics, for example, using the index method, which allows you to separate the dependence of the value of the general coefficient on the intensity of the process under study and its dependence on structural factors. Approximately the same can be achieved with the help of the so-called methods of standardization of demographic coefficients. These methods will be discussed in the following chapters.

Since, nevertheless, the general coefficients of natural movement of the population are somewhat popular, it is not out of place to get acquainted with their dynamics in our country in the post-war period (Table 4.1).

This table needs a little comment.

Before the Great Patriotic War, the total fertility rate (and the birth rate, in fact) was still very high, although it had been declining for a long time (at least after 1925). In the subsequent period, the birth rate declined almost steadily, not only as a result of a real decline in the birth rate, but also as a result of the aging of the age structure of the population. To date, it has fallen to an all-time low level, twice as low as in the most difficult years of the Great Patriotic War. We will not rush to judge the reasons for the fall in the birth rate in Russia to such a depth, this will be discussed in the next chapter.

The mortality rate, having decreased over 20 years, in the period 1940 - 1960, then grew steadily for almost 35 years. In fact, the dynamics of mortality was different, in some years the mortality rate really grew, in some years it decreased. In this case, the dynamics of the overall mortality rate is strongly influenced by the aging of the age structure of the population.

Table 4.1

Dynamics of the general coefficients of natural movement of the population of Russia (in ppm)

years	fertility	Mortality	natural increase	Marriage	Divorceability
	33,0	20,6	12,4	5,5	0,9
	26,9	10,1	16,8	12,0	0,5
	23,2	7,4	15,8	12,5	1,5
	14,6	8,7	5,9	10,1	3,0
	15,9	11,0	4,9	10,6	4,2
	13,4	11,2	2,2	8,9	3,8
	12,1	11,4	0,7	8,6	4,0
	10,7	12,2	-1,5	7,1	4,3
	9,4	14,5	-5,1	7,5	4,5
	9,6	15,7	-6,1	7,4	4,6
	9,3	15,0	-5,7	7,3	4,5
	9,0	15,0	-6,0	5,9	3,8
	8,6	13,8	-5,2	6,3	3,8

As a result of the combined changes in birth and death rates, the total rate of natural increase also declined until it became negative. How long? So far no one knows. Maybe forever.

The marriage rate in the country after the end of the war was very high, and this is not surprising. I must say that the marriage rate in Russia has always been high compared to, say, Western Europe, where in the past there was a so-called European type of marriage, which is characterized by a relatively high age of marriage and a high percentage of celibacy. Only in the most recent years, in the first half of the 1990s, did the total marriage rate in the country fall to an unusually (for Russia) low level. It is too early to judge the reasons. Too little time has passed to collect a sufficient amount of statistical and research materials for an in-depth analysis.

The divorce rate in the first years after the end of the war was very low, and hardly any explanation is needed here. Although it is difficult to say how much these statistics reflect the realities of life at that time. The war destroyed many families, and the breakup of a marriage was not always formalized legally. We will probably never know what proportion of marriages actually broke up in those days.

In the 1960s the divorce rate began to rise steadily. Here it should be taken into account that in 1965 the legal conditions for divorce were significantly eased, and therefore divorces that took place long ago, but were not legally formalized in a timely manner, were added to the actual number of divorces. The influence of this factor on the divorce rate continued for several years. In recent years, the overall divorce rate has stabilized at a very high level. It is higher than here, in Russia, only in the USA.

To estimate the height of the total fertility rate at different times, individual scientists proposed specially developed scales. I do not include them here for a number of reasons. Firstly, these scales are quite subjective and rather reflect the personal assessments of their authors. Secondly, there is no need for such scales. To estimate the birth rate on the basis of the value of the total fertility rate, it is enough to remember only one of its critical values, that is, the one that corresponds to the border of simple population reproduction (at which the population does not grow, but does not decrease either). With low total and infant mortality, the total fertility rate, corresponding to the simple reproduction of the population, is approximately 15-16 ‰. From this, one can roughly estimate the extent to which the current birth rate ensures the reproduction of the population in our country. To do this, it is enough to divide the actual birth rate in 1997 (8.6 ‰) by its critical value (15.0 ‰):

8.6: 15.0 = 0.57, or 57‰,

i.e., while maintaining this level of fertility for a long time, each next generation will be numerically less by 43% than the previous one.

GENERAL INFORMATION

By design features, natural lighting is divided into:

- lateral carried out through light openings in the outer walls (windows);

- upper carried out through lanterns and light openings in the ceiling, as well as light openings in places of height differences in adjacent buildings;

- combined - a combination of top and side natural lighting.

The necessary illumination of workplaces with natural light depends on the natural lighting system and the category of visual work performed, which is characterized by the size of the minimum object of distinction. The normalized characteristic of natural lighting is the coefficient of natural illumination (KEO), which is characterized by the ratio of horizontal illumination (E ext) measured at a height of I m from the floor inside the room to the horizontal illumination outdoors (E nar) created by the sky. KEO shows the proportion of natural light penetrating into the building and illuminating a conditional horizontal surface at a height of I m from the floor.

Natural lighting standards, depending on the nature of the work performed (type of work and degree of accuracy), are divided into 6 categories (SN 275-71 “Sanitary standards for the design of industrial enterprises” (Appendix 1).

Method for calculating the area of light openings. The required area of light openings with lateral natural lighting, necessary to ensure the normalized KEO, is determined by the formula:

(2)

S 0 - area of light openings, m 2;

S n - floor area of the room, m 2;

e min - normalized value of KEO (Appendix 1);

η 0 - the light characteristic of the window, depending on the depth of the room, the protrusion of the window and the ratio of the lengths of the sides (Appendix 2);

k 1 - coefficient taking into account the shading of windows by opposing buildings (Appendix H);

τ 0 - total light transmission coefficient, depending on indoor air pollution, glazing position (vertical, inclined), type of window bindings, etc. (Appendix 4);

r 1 - coefficient taking into account the reflection of light from the walls and ceiling of the room (Appendix 5).

Ways to determine the coefficient of natural light

A) Measurement of natural light.

Luxmeters are used to measure flat illumination. Most common luxmeter Yu-116. Luxmeter Yu-116 consists of a photocell with a set of absorbing nozzles and a galvanometer. The operation of the device is based on the photoelectric effect. The light flux falling on the selenium photocell causes an electric current, the value of which is fixed by the galvanometer needle.

For measuring production room lighting it is necessary to install the luxmeter sensor in the plane of the workplace, select the required scale, starting with a coarser one, and measure (read) the illumination.

When measuring KEO, the following conditions must be observed:

a) measurements of illumination inside and outside the premises are made simultaneously. If one luxmeter is available, the time between measurements of external and internal illumination must be reduced to the minimum possible;

b) KE0 measurements are possible only when the sky is covered with clouds, i.e. in diffusion scattering of light;

c) outdoor horizontal illumination is measured in an open area illuminated by the entire sky.

The procedure for measuring illumination is as follows:

a) in the room for which the KEO is determined, a base point is chosen that is well lit by natural light, so that the entire room is viewed from it;

b) the photocell of the luxmeter is laid horizontally on the working plane at the base point of measurement and the illumination is measured (E bases);

c) immediately measure the external illumination (E nar). At the same time, the photocell is closed with a light filter (E nar = E scale 100).

The KEO of the base point is:

% (3)

After defining KEO base point can be determined KEO any other point in the room. To do this, measure the illumination at the base point (E bases) and at the point where you want to measure KEO (E x). Then calculate according to the formula.

I. General indicators

1) fertility rate shows the number of live births per year ( N

Example. The average annual population of city A is 200 thousand people. (). In 1999, 2.8 thousand children were born ( N):

Consequently, 14 children per 1,000 inhabitants were born in the city during the year. This indicator can already be used to compare the birth rate in time (for the same locality) or territorial aspect (between different localities).

2) death rate shows the number of deaths per year ( M) per 1000 people. population of a certain area:

3) rate of natural increase :

4) vitality factor (Pokrovsky's index) characterizes the ratio between the birth rate and mortality rate:

II. Special and partial coefficients

1) fertility rate (fertility ) (or special birth rate) shows the number of births per year per 1000 women of childbearing age (age group 14-49):

Between general() And special () fertility rates there is the following dependency:

where is the proportion of women aged 15-49 in the total population.

2) age-specific birth and death rates .

A) defined as the ratio of the number of deaths per year at the age X years to the average annual population of this age group:

Where x- age group;

- number of deaths in a year aged x years;

is the average annual population of a given age group

That., age-specific mortality rates show the level of mortality in a particular age group of the population (in particular, using the formula (1e-14), mortality rates can be calculated for a certain gender, social, professional and other group of the population (in this case X identifies a population group.

b) age-specific fertility rates defined as the ratio of the number of births per year at the age X years to the average annual population of this age group (cf. p. 2, a):

V) total fertility rates show the number of children that a woman will give birth to for the entire childbearing period; is defined as the quotient of the sum age-specific fertility rates in one-year groups per 1,000 people (for example, this coefficient in 1999 in Russia as a whole was only 1.17).

3) coefficient of child (infantile ) mortality characterizes the mortality of children up to one year. It is calculated as the sum of two components: one of which is the ratio of the number of deaths under the age of one year from the generation born in the previous year (), to the total number of births in the same period (), and the second is the ratio of the number of deaths under the age of one year from the generation born in a given year (), to the total number of those born in the same year ():

It should be especially noted that child (infant) mortality rate in international statistics is regarded as one of the most important indicators of the standard of living of the population , and so, these indicators are as follows (data for 1992): Switzerland - 7, USA - 9, Russia - 18‰ (!) (for comparison - in one of the poorest countries in Europe - (in Romania) this figure is 23% ).

4) average duration indicator future life for any age group of the population is calculated by dividing the sum of lived (upcoming) person-years of life (to be lived by a population of people from age X up to the age limit inclusive) by the number of the studied generation (), who survived to the age X:

where is the sum of lived (forthcoming) person-years to be lived by a population of persons from age X up to and including the age limit, and

5) population turnover rate - the number of births and deaths per 1000 people on average per year:

6) (as a share of natural increase in the total turnover of the population):

In conclusion p. II what's between general And private coefficients of natural movement of the population, there is the following relationship: the overall coefficient is the average of the partial coefficients. Let's show this dependence on an example mortality rates:

General death rate also depends on age-specific mortality rates and from population structures. Ceteris paribus, an increase in the proportion of people of retirement age (i.e. aging population) leads to an increase crude death rate. Therefore, for a comparative analysis and dynamics of demographic processes, it becomes necessary to use such indicators in which the influence of the structural factor would be eliminated. To do this, consider item III.

III. Standardized odds, which are used to conduct a comparative analysis of the reproduction of the population in different territories or for one territory at different points in time.

1) population reproduction efficiency ratio , which is defined as the share of natural turnover in the total turnover of the population:

Example. The following data are available for two locations B and C in the region in 2009.

2.1. Natural lighting is of great physiological and hygienic importance for workers. It favorably affects the organs of vision, stimulates physiological processes, increases metabolism and improves the development of the body as a whole. Solar radiation warms and disinfects the air, purifying it from the causative agents of many diseases (for example, the influenza virus). In addition, natural light also has an important psychological significance, creating a feeling of direct connection with the environment among workers.

Natural lighting also has disadvantages: it is unstable at different times of the day and year, in different weather; unevenly distributed over the area of the production premises; with unsatisfactory organization, it can cause blinding of the organs of vision.

By design features, natural lighting is divided into side, top and combined.

Side lighting is created by the penetration of daylight through a window or other translucent openings in the walls of buildings. It can be single or double sided.

Overhead lighting is created by means of special devices in the roof of buildings: lanterns of various designs, light openings in the plane of the coating.

Since the level of natural light depends on the latitude of the area, time of year and day, weather conditions, that is, it varies over a very wide range, the illumination inside buildings is usually judged not by its absolute value in lux, but by the coefficient of natural illumination (KEO).

KEO (Natural Illumination Factor) is the percentage ratio of the illumination at some point indoors to the simultaneously measured outdoor horizontal illumination from the light of a fully open sky.

The following factors influence the level of illumination of a room with natural light: light climate; area and orientation of light openings; the degree of purity of the glass in the light openings; painting the walls and ceiling of the room; depth of the room; the presence of objects that cover the window both from the inside and outside the room.

2.2. Since natural lighting is not constant throughout the day, a quantitative assessment of this type of lighting is carried out according to a relative indicator - the coefficient of natural illumination (KEO):

where EVN is the illumination created by the light of the sky (direct or reflected) at some point inside the room;

EH - the illumination of a horizontal surface, created at the same time from the outside by the light of a completely open sky (direct or reflected, lux).

Illumination of a room with natural light is characterized by the KEO values of a number of points located at the intersection of two planes: a conditional working surface and a vertical plane of the characteristic section of the room. The conditional working surface is a horizontal plane located at a height of 0.8 m from the floor.

A characteristic section is a cross section in the middle of the room, the plane of which is perpendicular to the plane of the glazing of the side light openings.

Normalized values of KEO are determined by the "Building Norms and Rules" (SNiP II - 4-79, currently in force in Ukraine, and revised in 1985). One of the main parameters that determine the KEO is the size of the object of difference, which is understood as the object in question or its part, as well as the defect that needs to be detected. The KEO value is normalized depending on the characteristics of visual work. With lateral natural lighting, the minimum values \u200b\u200b(emin) are normalized, with upper and side lighting - the average value (esr). The value of emin with lateral one-sided lighting is determined at a distance of 1 m from the wall, the furthest from the light openings.

When calculating natural lighting, the areas of light holes (windows, lanterns) are determined to ensure the normalized KEO value.

The calculation of the area of windows with side lighting is carried out according to the following ratio:

where So is the area of windows;

Sn - floor area of the room;

eH - normalized value of KEO;

kz - safety factor;

zo - light characteristic of windows;

kZD - coefficient taking into account the shading of windows opposite

buildings;

pho - total light transmission coefficient;

r is a coefficient that takes into account the increase in KEO due to the light reflected from the surfaces of the room and the surface layer adjacent to the building (earth, grass).

It was said above that the illumination created in the premises by natural light varies over an extremely wide range. These changes are determined by the time of the day, the time of the year, and meteorological factors: the state of cloud cover and the reflective properties of the land cover. With variable cloudiness, the amount of illumination created by daylight can change dozens of times in a short period of time.

The inconsistency of natural lighting in rooms over time has necessitated the introduction of an abstract unit of measurement of natural light, called coefficient of natural light.

The coefficient of natural illumination is the percentage ratio of illumination at a given point in the room to the simultaneous illumination of a point located on a horizontal plane outside the room and illuminated by diffused light from the entire sky (Fig. 47).

Rice. 47. :

E m - illumination indoors at point M;

E n - external horizontal illumination.

Analytically, the daylight factor is expressed by the formula e \u003d E m / E n * 100%,

e is the coefficient of natural illumination;

E m - illumination indoors at point M in lux;

E n - outdoor illumination on a horizontal surface in lux.

Consequently, the coefficient of natural illumination shows what proportion of the simultaneous horizontal illumination in an open area with diffuse light from the sky is the illumination at the point in the room under consideration.

The sufficiency of natural lighting in the premises is regulated by the norms that set the values of the coefficients of natural illumination, depending on the conditions of visual work.

Table 9 Normalized values of natural light coefficients in the premises of industrial buildings

According to the current norms of natural light illumination (Table 9), production facilities are divided into nine categories according to the type of work performed. The accuracy of visual work is determined by the size of the objects of distinction. The object of distinction is understood as the smallest object (element) that requires distinction in the process of work (a wire thread, a line in a drawing, a scratch on a metal surface, dimension lines of measuring instruments, etc.).

Rice. 48. Scheme of the distribution of natural light coefficients according to the section of the room:

a - for one-sided side lighting at different levels of the working plane; b - for bilateral side lighting; c - for overhead lighting; g - for combined lighting; 1 - level of the working plane; 2 - light profile curve; 3 - the level of the average value of the coefficient of natural illumination; M - point with the minimum value of the illumination coefficient

In rooms with lateral one-sided lighting, the minimum value of the coefficient of natural illumination is normalized at a point on the working plane, the furthest from the light opening (Fig. 48, a).

With lateral bilateral lighting and symmetrical light openings, the minimum value of the coefficient of natural illumination in the middle of the room is normalized (Fig. 48, b), and if there is a free passage in the middle of the room, at the boundaries of this passage. If the light openings are not symmetrical, the minimum value of the coefficient of natural illumination is taken to be the smallest value of the coefficient from among those calculated for various points in the room with the expected lowest illumination.

In rooms illuminated by overhead or combined light, the average value of the natural light coefficient in the span or room is normalized (Fig. 48, c and d), which is determined by the formula

e 1 e 2 ,. . ., e n are the values of the coefficient of natural illumination at individual points located at an equal distance from each other;

n is the number of points at which the natural light factor is determined (at least five such points are taken).

In rooms with combined lighting, the total value of the average coefficient of natural illumination is determined by the formula e cf \u003d e f + e o

e f - the average value of the coefficient of natural illumination from the lantern;

e o - the average value of the coefficient of natural light from the windows.

In addition to the intensity of natural lighting, the uniformity of natural lighting is normalized, which in industrial premises of the 1st and 2nd categories of work with overhead lighting should be at least 0.5, and for works of the 3rd and 4th categories - at least 0.3.

The uniformity of illumination is characterized by the ratio of the minimum coefficient of natural illumination e min to its maximum value e max on the working plane within the characteristic section of the room (usually in the middle of the room along the axis of the light opening or along the axis of the wall between the light openings).

For industrial premises with side and combined lighting, the unevenness of natural lighting is not standardized.

The dimensions and location of light openings in the premises, as well as compliance with lighting standards, are checked by calculation. This is guided by the following considerations.

Rice. 49. Scheme for determining the coefficient of natural light, taking into account reflected light

The luminous flux falling into one or another point of the room (Fig. 49) is summed up from direct diffuse light from the sky e n (taking into account light losses), light reflected from the internal surfaces of the room e o, and light reflected from the surface of the earth e s . Thus, e \u003d e n + e o + e s.

Illuminance e n, obtained indoors from the diffuse light of the sky, depends on the size of the light openings and their placement. It increases with an increase in the area of light openings, as well as when placing light openings in the upper part of the walls and in the covering of buildings.

The illumination e o obtained due to the light reflected from the internal surfaces of the room depends on the color of the floor, the color of the walls and ceiling. In rooms with light floors, with a ceiling and walls painted with white paint, the illumination increases by 2 or more times.

Illuminance e z is taken into account only for buildings with side lighting. The reflected light from the surface of the territory adjacent to the building, with side lighting of rooms with a light ceiling color, increases the illumination in the rooms by 30% or more with light soil (sand) or when the soil is covered with light ceramic tiles.