Drawing of the room with combined lighting. Calculation of lateral one-sided natural lighting. Combination of KEO standards and illumination standards

When illuminating industrial premises, use daylight, is carried out due to direct and reflected light of the sky.

From a physiological point of view, natural lighting is the most favorable for humans. During the day, it varies within a fairly wide range depending on the state of the atmosphere (cloudiness). The light, having entered the room, is repeatedly reflected from the walls and ceiling, hits the illuminated surface at the point under study. Thus, the illumination at the point under study is the sum of the illuminations.

Structurally, natural lighting is divided into:

lateral(one-, two-sided) - carried out through light openings (windows) in the outer walls;

top- through light openings located in the upper part (roof) of the building;

combined– a combination of top and side lighting.

Natural lighting is characterized by the fact that the created illumination varies depending on the time of day, year, meteorological conditions. Therefore, as a criterion for assessing natural lighting, a relative value is taken - daylight ratio(KEO), or e, independent of the above parameters.

Daylight ratio (KEO) - the ratio of illumination at a given point inside the room E ext to the simultaneous value of the external horizontal illumination E n, created by the light of a completely open sky (not covered by buildings, structures, trees) expressed as a percentage, i.e.:

(8) Where E ext– illumination indoors at the control point, lx;

E n - simultaneously measured illumination outside the room, lx.

For measuring actual KEO needs to be carried out simultaneous measurements indoor lighting E ext at the control point and outdoor illumination on a horizontal platform under the fully open sky E n , free from items(buildings, trees ) covering parts of the sky. KEO measurements can only be carried out with continuous uniform ten-point cloudiness(overcast, no gaps). Measurements are taken by two observers using two lux meters simultaneously (observers must be equipped with chronometers).

Checkpoints for measurements should be selected in accordance with GOST 24940–96 “Buildings and structures. Methods for measuring illumination.

KEO values for various premises lie in the range of 0.1–12%. Rationing of natural lighting is carried out in accordance with SNiP 23-05-95 "Natural and artificial lighting".

In small rooms with unilateral lateral illumination is normalized (i.e. the actual illumination is measured and compared with the norms) minimum value of KEO at a point located at the intersection of the vertical plane of the characteristic section of the premises and the conditional working surface at a distance of 1 m from the wall, most remote from light openings.

Working surface- the surface on which the work is performed and on which the illumination is normalized or measured.

Conditional work surface- a horizontal surface at a height of 0.8 m from the floor.

Typical section of the room- this is a cross section in the middle of the room, the plane of which is perpendicular to the plane of the glazing of the light openings (with side lighting) or the longitudinal axis of the spans of the room.

At bilateral lateral lighting rationing minimum value of KEO- in the plane in the middle premises.

IN oversized industrial premises at lateral lighting, the minimum value of KEO is normalized at the point remote from light openings:

at 1.5 heights of the room - for works of I-IV categories;

at 2 heights of the room - for works of V-VII categories;

at 3 heights of the room for work of the VIII category.

At upper and combined lighting is normalized average value of KEO at points located at the intersection of the vertical plane of the characteristic section of the room and the conditional work surface or floor. The first and last points are taken at a distance of 1 m from the surface of walls or partitions.

(9)

Where e 1 , e 2 ,..., e n - KEO values at individual points;

n- number of lighting control points.

It is allowed to divide the room into zones with different conditions of natural light, the calculation of natural light is carried out in each zone independently of each other.

At inadequate by standards natural light V industrial premises his supplement with artificial lighting. Such lighting is called combined .

In industrial premises with visual work of I-III categories, combined lighting should be arranged.

In large-span assembly shops, in which work is carried out in a significant part of the volume of the room at different levels from the floor and on work surfaces differently oriented in space, overhead natural lighting is used.

Natural light should evenly illuminate workplaces. For overhead and combined natural lighting, determine irregularity natural lighting of industrial premises, which should not exceed 3:1 for works I–VI discharges according to visual conditions, i.e.

(10)

certain according to table 1 SNiP 23-05-95 KEO value, to be specified taking into account the characteristics of visual work, lighting systems, location of buildings in the country according to the formula

, (11)

where N- number of the natural light supply group (Appendix D SNiP 23-05-95);

e n- coefficient of natural light (Table 1 SNiP 23-05-95);

m N- coefficient of light climate, determined depending on the location of the building on the territory of the country and the orientation of the building relative to the cardinal points (see Table 4 SNiP 23–05–95).

GENERAL INFORMATION

The organization of rational lighting of workplaces is one of the main issues of labor safety. The correct lighting device largely depends industrial injuries, performance and quality of work performed.

There are two types of lighting: natural And artificial. When calculating them, one should be guided by building codes and the rules of SNiP 23-05-95 "Natural and artificial lighting".

Methodological instructions give calculation methods various kinds natural lighting.

In accordance with the requirements of SNiP 23-05-95, all production, storage, amenity and administrative office premises must, as a rule, have natural lighting. It is not arranged in rooms where the photochemical effect of natural light is contraindicated for technical and other reasons.

Natural lighting can not be arranged: in sanitary facilities; expectant health centers; rooms for personal hygiene of women; corridors, passages and passages of industrial, auxiliary and public buildings. Natural lighting can be side, top, combined and combined.

Lateral daylight- this is the natural illumination of the room with light entering through the light openings in the outer walls of the building.

With one-sided side lighting, it is normalized daylight factor value (KEO) at a point located at a distance of 1 m from the wall (Fig. 1.1a), i.e., the most distant from the light openings at the intersection of the vertical plane of the characteristic section of the room and the conditional working surface (or floor). With side lighting, the effect of shading from opposing buildings is taken into account by the shading factor K ZD(Fig. 1.26).

With bilateral side lighting, it is normalized minimum value KEO at a point in the middle of the room at the intersection of the vertical plane of the characteristic section of the room and the conditional work surface (or floor) (Figure 1.16).

Top natural light- this is the natural illumination of the room with light penetrating through the light openings in the roof of the building and lanterns, as well as through the light openings in the places of height differences of adjacent buildings.

Figure 1.1 - Natural light distribution curves: A - with one-sided side lighting; b - bilateral side; 1 - the level of the conditional working surface; 2 - curve characterizing the change in illumination in the plane of the section of the room; RT - point of minimum illumination with side one-sided and two-sided lighting e min .

With top or top and side natural lighting, it is normalized average value KEO at points located at the intersection of the vertical plane of the characteristic section of the room and the conditional working surface (or floor). The first and last points are taken at a distance of 1 m from the surface of walls or partitions or from the axes of rows of columns (Fig. 3.1a).

It is allowed to divide the room into zones with side lighting (zones adjacent to external walls with windows) and zones with overhead lighting; normalization and calculation of natural lighting in each zone are made independently. This takes into account the nature of visual work. Conditional working surface - conventionally accepted horizontal surface located at a height of 0.8 m from the floor.

Combined lighting is lighting in which natural and artificial light is used simultaneously during daylight hours. At the same time, natural lighting that is insufficient in terms of visual work is constantly supplemented by artificial lighting that meets special requirements for premises (SNiP 23-05-95 on lighting design) with insufficient natural lighting.

Figure 1.2 - Scheme for designating the dimensions of a building for calculating natural side lighting:

A - size designation scheme for calculating natural side lighting: - width of the room;

L PT- distance from outer wall to the calculated point (RT);

1 m - distance from the wall surface to the design point (RT);

In p- depth of the room; h 1 - height from the level of the conditional work surface to the top of the window;

h2- height from the floor level to the conditional working surface (0.8 m);

L p- the length of the room; N- room height; d- wall thickness;

6 - scheme for determining the coefficient K ZD: Nkz- cornice height

of the opposing building above the window sill of the building in question; Lj# - distance

between the considered and opposing building; M- shading border

The norms for the minimum illumination of premises are determined keo, representing the ratio of natural light , created at some point of a given plane inside the room by the light of the sky (directly or after reflections), to the simultaneous value of the external horizontal illumination , created by the light of a fully open sky, defined in %.

Values KEO for rooms requiring various conditions illumination, taken in accordance with SNiP 23-05-95, tab. 1.1.

The design of natural lighting for buildings should be based on a detailed study of technological or other labor processes performed in the premises, as well as on the light and climatic features of the construction site of buildings. In this case, the following characteristics should be defined:

Characteristics of visual work, determined depending on the smallest size of the object of distinction, the category of visual work;

Location of the building on the light climate map;

Normalized value KEO taking into account the characteristics of visual work and light-climatic features of the location of buildings;

Required uniformity of natural lighting;

dimensions and the location of the equipment, the possible dimming of working surfaces;

The desired direction of incidence of the light flux on the work surface;

The duration of the use of natural lighting during the day for different months of the year, taking into account the purpose of the premises, the mode of operation and the light climate of the area;

The need to protect the premises from the blinding action of direct sunlight;

Additional lighting requirements arising from the specifics technological process and architectural requirements for the interior.

The design of natural lighting is carried out in a certain sequence:

1st stage - determination of requirements for natural lighting of premises; determination of the normative value KEO according to the category of visual works prevailing in the room:

Choice of lighting system;

Choice of types of light opening and light-transmitting material;

Choice of means to limit the blinding effect of direct sunlight;

Accounting for the orientation of buildings and light openings on the sides of the horizon;

2nd stage - performing a preliminary calculation of the natural lighting of the premises; i.e. calculation of the glazing area soc:

Clarification of the parameters of light openings and the room;

3rd stage - performing a verification calculation of natural lighting in the premises:

Determination of premises, zones and areas with insufficient natural lighting according to the norms;

Determination of requirements for additional artificial lighting of premises, zones and areas with insufficient natural light;

4th stage - making the necessary adjustments to the natural lighting project and re-testing calculation (if necessary).

CALCULATION OF SINGLE-SIDE LATERAL NATURAL LIGHTING

In most cases, natural lighting of industrial and administrative-office premises is carried out by lateral one-sided lighting (Fig. 1.1a; Fig. 1.2a).

The method for calculating natural side lighting can be reduced to the following.

1.1. The category of visual work and the normative value of the coefficient of natural light are determined.

The category of visual work is determined depending on the size of the smallest size of the object of distinction (as assigned) and in accordance with this, according to SNiP 23-05-95 (Table 1.1), the standard value of the natural light factor is established , %.

object of distinction- this is the object under consideration, its individual parts or a defect that needs to be distinguished in the process of work.

1.2. The required glass area is calculated soc:

where is the normalized value KEO for buildings located in different areas;

Light characteristic of the window;

A coefficient that takes into account the darkening of windows by opposing buildings;

- floor area, m 2;

Overall light transmittance;

Coefficient that takes into account the reflection of light from surfaces in the room.

The values of the parameters included in formula (1.1) are determined by formulas, tables and graphs in a certain sequence.

Normalized value KEO e N for buildings located in different areas should be determined by the formula

e N \u003d e H -m N (%),(1.2)

where - value keo,%, is determined according to the table. 1.1;

m N- coefficient of light climate (Table 1.2), taken into account the group administrative regions according to the resources of the light climate (Table 1.3).

The value obtained by formula (1.2) KEO round to tenths.

1,5%; m N = 1,1

where - the length of the room (according to the instructions of appendix 1);

Depth of the room, m, with side one-sided lighting equal to +d,(Fig. 1.2a);

Width of the room (according to the assignment of appendix 1);

d- wall thickness (according to the assignment of appendix 1);

- height from the level of the conditional working surface to the top of the window, m (Appendix 1).

Knowing the values of relations (1.3), according to Table. 1.4 find the value of the light characteristic of the window

To calculate the coefficient , taking into account the dimming of windows by a neighboring building (Fig. 1.26), it is necessary to determine the ratio

where is the distance between the considered and opposing building, m;

The height of the cornice of the opposing building above the window sill of the window in question, m

Depending on the value according to the table. 1.5 find ratio

The total light transmission coefficient is determined by the expression

where is the light transmission coefficient of the material (Table 1.6);

The coefficient taking into account the loss of light in the window casings of the light openings (Table 1.7);

Coefficient taking into account light losses in load-bearing structures, with side daylight = 1;

- coefficient that takes into account the loss of light in sun protection devices (Table 1.8).

When determining the coefficient that takes into account the reflection of light from surfaces in the room, it is necessary to calculate:

a) weighted average coefficient of reflection of light from walls, ceiling and floor:

Where - wall, ceiling, floor area, m 2 , determined by the formulas:

where - the width, length and height of the walls of the room, respectively (as assigned by appendix 1).

The source of natural light is the radiant energy of the sun. The natural average outdoor illumination during the year fluctuates sharply by months and hours, reaching a maximum in June and a minimum in December in the middle zone of our country. In addition, during the day, the illumination first increases - up to 12 hours, then decreases - in the period from 12 to 14 hours and gradually drops - up to 20 hours.

Natural lighting has both positive and negative sides.

Solar radiation strongly affects the skin, internal organs and tissues and, above all, the central nervous system. Interestingly, this influence is not limited to the time when a person is in the sun, but continues after he goes indoors or when night falls. Doctors call it reflex.

The action of sunlight begins with the effect on the skin. Human skin unprotected by clothing reflects from 20 to 40% of the visible and closest invisible infrared rays that have fallen on it (20% reflects the skin of a tanned person, and 40% is the most untanned, white skin). The absorbed part (60...65%) of radiant energy penetrates under the outer skin and affects the deeper layers of the body.

Ultraviolet and some infrared rays are reflected by the skin to a lesser extent and are absorbed more strongly by the horny, coarser layer of the skin.

In people, long time working in the North, in mines, subways or simply in cities in central Russia, those who are mostly indoors during the day and move along the streets by transport, solar starvation develops. The point is that ordinary window panes buildings to a small extent pass physiologically active ultraviolet rays, and in cities, even without that, little of them reaches the Earth's surface as a result of air pollution with dust, smoke, and exhaust gases.

With solar starvation, the skin becomes pale, cold, loses its freshness. She is poorly supplied nutrients and oxygen. In it, blood and lymph circulate weaker, slag decay products are poorly removed from it, and poisoning of the body with waste substances begins. In addition, the capillaries become more fragile, and therefore the tendency to hemorrhage increases.

Those who experience solar starvation undergo painful, unpleasant metamorphoses, affecting both the sphere of the psyche and the physical state. First of all, there are disruptions nervous system: memory and sleep worsen, excitability in some increases and indifference, lethargy in others. With the deterioration of calcium metabolism (the appearance of difficulties in the assimilation of dietary calcium and phosphorus, which continue to be excreted from the body, and, consequently, the tissues are depleted of these essential substances), teeth begin to deteriorate intensively, bone fragility increases. Thus, with prolonged solar fasting, mental abilities and working capacity decrease, fatigue and irritation set in very quickly, mobility decreases, and the ability to fight microbes that enter the body worsens (immunity decreases). Undoubtedly, a person experiencing solar starvation is more likely to get colds and other infectious diseases, and the disease is of a protracted nature. In these cases, fractures, cuts and any injuries heal slowly and poorly. There is a tendency to pustular diseases in those who have not suffered from this before, and the course of chronic diseases worsens in those who already have them, inflammatory processes are more difficult, which is associated with an increase in the permeability of the walls of blood vessels, and the tendency to edema increases.

Given the degree of beneficial effects of natural light on the human body, occupational health requires maximum use of natural light. It is not arranged only where it is contraindicated by the technological conditions of production, for example, when storing light-sensitive chemicals and products.

So, solar lighting increases labor productivity by up to 10%, and the creation of rational artificial lighting - up to 13%, while in a number of industries, marriage is reduced to 20 ... 25%. Rational lighting provides psychological comfort, helps to reduce visual and general fatigue, reduces the risk of industrial injuries.

By design, natural lighting is divided into:

Lateral, carried out through window openings, one- or two-sided (Fig. 4.3 A, b);

Upper, when light enters the room through aeration or skylights, openings in the ceilings (Fig. 4.3 V);

Combined, when side lighting is added to the top lighting (Fig. 4.3 G).

Natural lighting is used during the daytime. It provides good illumination, uniformity; due to its high diffuseness (scattering), it has a favorable effect on vision and is economical. Besides sunlight has a biologically healing and tonic effect on a person.

The primary source of natural (daylight) light is the Sun, which radiates a powerful stream of light energy into the world space. This energy reaches the Earth's surface in the form of direct or scattered (diffuse) light. In lighting calculations for natural lighting of premises, only diffuse light is taken into account.

The amount of natural outdoor illumination has large fluctuations as seasons, as well as by hours of the day. Significant fluctuations in natural light during the day depend not only on the time of day, but also on changes in cloudiness.

Thus, natural light sources have features that create dramatically changing lighting conditions. The task of designing natural lighting in rooms is reduced to rational use natural light resources available in the area.

Daylight rooms is carried out through the light openings and can be made in the form of a side, top or combined.

Lateral- carried out through windows in the outer walls of the building; top- through light lanterns located in the ceilings and having various shapes and sizes; combined through windows and skylights.

In natural light, the distribution of illumination throughout the room, depending on the type of illumination, is characterized by the curves shown in Fig. 36, a-g.

Rice. 36. Scheme of distribution of natural light coefficients in rooms depending on the location of light openings:

a - one-sided - lateral; b - bilateral - lateral; in - upper; d - combined (side and top)

The natural light curves of the premises must be taken into account when arranging the equipment so that it does not obscure the workplaces that are farthest from the light openings.

Natural lighting in the room is determined daylight ratio(KEO) - e, which is the ratio, expressed as a percentage, of the illumination of any point in the room to a point on a horizontal plane outside the room, illuminated by the diffused light of the entire sky, at the same moment in time:

where E vn - the illumination of a point inside the room; E nar - the illumination of a point outside the room.

The point for measuring the illumination inside the room is determined: with side lighting - at the line of intersection of the vertical plane of the characteristic section of the room (axis of the window opening, etc.) and the horizontal plane located at a height of 1.0 m from the floor and at a distance farthest from light opening; with overhead lighting or combined (side and top) - on the line of intersection of the vertical plane of the characteristic section of the room and the horizontal plane at a height of 0.8 m from the floor.

The coefficient of natural illumination is set by the norms and with side lighting it is defined as the minimum - e min, and with the upper and combined as an average - e cf.

The values of the coefficients of natural illumination for middle lane the European part of the USSR, established by SNiP II-A.8-72, are given in Table. 6.

Table 6

Under the concept object of distinction means the object in question, its separate part or a distinguishable defect (for example, a thread of a fabric, a point, a risk, a crack, a line forming a letter, etc.), which must be taken into account in the process of work.

When determining the necessary natural illumination of workplaces in industrial premises, in addition to the natural illumination coefficient, it is necessary to take into account the depth of the room, floor area, windows and lanterns, dimming by neighboring buildings, shading of windows by opposing buildings, etc. Accounting for the influence of these factors is carried out by the correction factors of Appendix 2 of SNiP II -A.8-72.

Using this application, you can determine the area of light openings (windows or lanterns) using the following formulas, depending on the type of room lighting:

with side lighting

where m is the coefficient of the light climate (excluding direct sunlight), determined depending on the location of the building; c - coefficient of sunshine climate (taking into account direct sunlight). The normalized value of e n is the minimum allowable.

The territory of the USSR is divided into V zones according to the light climate (I is the northernmost, V is the southernmost):

Sunshine climate- a characteristic that takes into account the zone of the light climate and the luminous flux penetrating through the light openings into the room during the year due to direct sunlight, the likelihood of sunshine, the orientation of the light openings to the sides of the horizon and their architectural and constructive solution.

Sunshine factor With ranges from 0.65 to 1.

The task of calculating natural lighting is to determine the ratio of the total area of glazed openings of windows and lanterns to the floor area (S f / S p). The minimum values of this ratio are given in Table. 7.

Table 7

Specified in table. 7 values are determined based on the condition that the glass cleaning in the room, as well as the painting of walls and ceilings, are carried out regularly in the following terms. With a slight release of dust, smoke and soot - at least twice a year; painting - at least once every three years. With significant emissions of dust, smoke and soot - at least four times a year; painting - at least once a year.

Contaminated glass of light openings (windows and lanterns) can reduce the illumination of premises by five to seven times.

Premises with a permanent stay of people should, as a rule, have natural lighting - lighting the premises with skylight (direct or reflected). Natural lighting is divided into side, top and combined (top and side).

ЎNatural lighting of premises depends on:

1. Light climate - a set of natural lighting conditions in a particular area, which are made up of general climatic conditions, the degree of transparency of the atmosphere, as well as reflective abilities environment(albedo of the underlying surface).
2. Insolation regime - the duration and intensity of illumination of the room by direct sunlight, depending on the geographical latitude of the place, the orientation of buildings to the cardinal points, the shading of windows by trees or houses, the size of the light openings, etc.

Insolation is an important healing, psycho-physiological factor and should be used in all residential and public buildings with permanent residence of people, with the exception of individual rooms public buildings where insolation is not allowed due to technological and medical requirements. According to SanPiN No. RB, such premises include:

§ operating rooms;
§ intensive care rooms of hospitals;
§ exhibition halls of museums;
§ chemical laboratories of universities and research institutes;
§ book depositories;
§ archives.

The insolation regime is estimated by the duration of insolation during the day, the percentage of the insolated area of the room and the amount of radiative heat entering the room through openings. The optimal efficiency of insolation is achieved by daily continuous exposure to direct sunlight of the premises for 2.5 - 3 hours. natural lighting insolation

ЎDepending on the orientation of the windows of buildings to the cardinal points, there are three types of insolation regime: maximum, moderate, minimum. (Appendix, Table 1).

With a western orientation, a mixed insolation regime is created. In terms of duration, it corresponds to a moderate, in terms of air heating - to the maximum insolation regime. Therefore, according to SNiP 2.08.02-89, the windows of intensive care units, children's wards (up to 3 years old), and playrooms in children's departments are not allowed to be oriented to the west.

In mid-latitudes (territory of the Republic of Belarus), for hospital wards, day rooms for patients, classes, group rooms of children's institutions, the best orientation that provides sufficient illumination and insolation of the premises without overheating is south and southeast (permissible - SW, E).

The windows of operating rooms, resuscitation rooms, dressing rooms, treatment rooms, delivery rooms, offices of therapeutic and surgical dentistry are oriented to the north, northwest, northeast, which ensures uniform natural illumination of these rooms with diffused light, eliminates overheating of the rooms and glare sun rays, as well as the appearance of gloss from a medical instrument.

Rationing and assessment of natural lighting of premises

Rationing and hygienic assessment of natural lighting of existing and planned buildings and premises is carried out in accordance with SNiP II-4-79 by lighting (instrumental) and geometric (calculation) methods.

The main lighting indicator of natural lighting of premises is the coefficient of natural illumination (KEO) - the ratio of natural illumination created at some point in a given plane inside the premises by sky light to the simultaneous value of external horizontal illumination created by the light of a completely open sky (excluding direct sunlight), expressed in percentage:

KEO \u003d E1 / E2 100%,

where E1 - indoor illumination, lx;

E2 - outdoor illumination, lx.

This coefficient is an integral indicator that determines the level of natural light, taking into account all the factors that affect the conditions for the distribution of natural light in the room. Measurement of illumination on the working surface and in the open air is carried out with a luxmeter (U116, Yu117), the principle of operation of which is based on the conversion of the energy of the luminous flux into electricity. The receiving part is a selenium photocell with light-absorbing filters with coefficients of 10, 100 and 1000. The device's photocell is connected to a galvanometer, the scale of which is calibrated in lux.

ЎWhen working with a light meter, the following requirements must be observed (MU RB 11.11.12-2002):

· the receiving plate of the photocell should be placed on the working surface in the plane of its location (horizontal, vertical, inclined);
· the photocell must not be subject to accidental shadows or shadows from a person and equipment; If workplace is obscured during operation by the working or protruding parts of the equipment, then the illumination should be measured in these real conditions;
· measuring device should not be located near sources of strong magnetic fields; installation of the meter on metal surfaces is not allowed.

The coefficient of natural illumination (according to SNB 2.04.05-98) is normalized for various premises, taking into account their purpose, the nature and accuracy of the visual work performed. In total, 8 digits of visual work accuracy are provided (depending on the smallest size of the object of distinction, mm) and four sub-digits in each digit (depending on the contrast of the object of observation with the background and the characteristics of the background itself - light, medium, dark). (Appendix, Table 2).

With side one-sided lighting, the minimum value of KEO is normalized at the point of the conditional working surface (at the level of the workplace) at a distance of 1 m from the wall farthest from the light opening. (Appendix, Table 3).

Geometric method for estimating natural light:

1) Light coefficient (SC) - the ratio of the glazed area of windows to the floor area of \u200b\u200bthe given room (the numerator and denominator of the fraction are divided by the numerator value). The disadvantage of this indicator is that it does not take into account the configuration and placement of windows, the depth of the room.
2) Coefficient of laying depth (deepening) (KZ) - the ratio of the distance from the light-bearing wall to the opposite wall to the distance from the floor to the upper edge of the window. KZ should not exceed 2.5, which is ensured by the width of the lintel (20-30 cm) and the depth of the room (6 m). However, neither SC nor SC do not take into account the darkening of windows by opposing buildings, therefore, the angle of incidence of light and the angle of the opening are additionally determined.
3) The angle of incidence indicates at what angle the rays of light fall on a horizontal work surface. The angle of incidence is formed by two lines emanating from the point of assessment of lighting conditions (workplace), one of which is directed to the window along the horizontal working surface, the other - to the upper edge of the window. It must be at least 270.
4) The angle of the hole gives an idea of the size of the visible part of the sky, illuminating the workplace. The corner of the hole is formed by two lines emanating from the measurement point, one of which is directed to the upper edge of the window, the other to the upper edge of the opposing building. It must be at least 50.

The evaluation of the angles of incidence and opening should be carried out in relation to the workstations furthest from the window. (Appendix, Fig. 1).