Light formula: calculating the area of ​​windows in a country house

For multi-apartment multi-storey buildings, as well as for standard individual construction projects, the window area in a living room is a parameter calculated by specialists in advance, and for the apartment owner it does not matter, since it already meets all norms and standards. But for developers who build their own housing from scratch, according to their own design, window area is as important a parameter as the grade of cement or the strength of concrete. The calculated glazing area helps not only to provide the correct lighting in the room - it also means the correct arrangement of furniture, and the correct calculations of the floor beam of the opening, and much more.

Window area calculation table

Why is it important to know the window area?

Windows are very specific designs.
On the one hand, they provide sufficient illumination of the room, on the other hand, they are the largest “black hole” through which heat escapes to the street. Both extremes are usually the result of errors in construction calculations or lack thereof.

According to construction rules, the minimum amount of light penetrates into a room in which the total area of ​​all windows is 10–12.5% ​​of the total area of ​​the room.

In this case, not only the width and height of the window is important, but their ratio. The closer the proportion is to a harmonious rectangle, the better it is perceived visually and the more convenient it is to use.

A window that is close to ideal is a rectangle with the correct proportions (for example: 80 cm wide and 130 cm high).

In order to make it convenient to look outside, the upper edge of the wall under the window should be no higher than 90–100 cm. In turn, the upper edge of a convenient window is at a height of about cm from the floor and leaves enough space for attaching curtains, blinds or a roller shutter.

How to choose?

You should not trust standard sizes, since they do not exist in principle - the thickness of the walls and the height of the openings in all houses are different, and accordingly, the standards are different.

It is necessary to invite a measurer who will correctly measure the measurements, that is, height and width. However, preliminary measurements can be made independently to calculate the approximate cost of the finished structure.

In rooms where residents and their guests will stay for a long period of time, the ratio of windows to room area should be 1:8.

If the window is the only one in the room, place it in the center of a long wall and higher - in this case, the light will fall evenly throughout the room and flow evenly. The upper slope should not be created too far from the ceiling.

When searching for the optimal size and shape for a window, you need to approach it wisely and take into account several features. One of these is the degree of illumination. In order to plan the dimensions of the openings well, and most importantly, correctly, the following rules should be followed:

1. The most comfortable lighting for a person is the kind of lighting in which the width of the windows is at least 55% of the width of the entire room.
2. According to the rules, the lowest illumination is achieved provided that the glazing area is at least 10-12.5% ​​of the total area of ​​the room.

How to calculate the approximate size of a window in an apartment or house

Even at the design stage, all parameters of optimal glazing for each specific room are determined. The calculations are quite complex for a non-specialist, so let’s consider their results for one living room at an angle of incidence of daylight from 18 to 30 degrees.

For comfortable lighting, the ratio of the glass area to the floor area of ​​this room should be from 1/8 to 1/5. This means that the window will occupy an area of ​​14–17% of the floor area.

As for the height of the window sill, it is determined by the purpose of the room:

• in living rooms - from 70 to 90 cm;
• in work areas - from 90 to 100 cm;
• in the kitchen - 125 cm;
• in bathrooms and utility rooms - from 130 to 150 cm;
• in dressing rooms - 175 cm.

Glazing parameters

Any of the parameters necessary to ensure the best glazing of the room are calculated at the design stage, and they are individual. Independent calculation is quite complicated for a non-professional, so as an example, let’s look at ready-made results when light rays fall at an angle of 18–30° for various types of rooms. Comfortable lighting can be achieved provided that the glazing area is related to the floor area as 1 to 8 - 1 to 5. In other words, the window opening should make up 14–17% of the floor surface. Depending on the location of the house and its number of storeys, the angle of incidence of light changes, therefore, the illumination also changes. Therefore, with nearby tall neighboring houses, the decrease in illumination is compensated by large light openings.

As for its location, two factors are taken into account:

convenience and safety of looking outside; the presence of free space above the top edge, sufficient for attaching blinds, curtains, etc.

The choice of window sill height depends on the type of room:

for residential – 0.7–0.9 m; workers – 0.9–1.0 m; dressing rooms - 1.75 m; in the kitchen -1.25 m.

How experts calculate glazing area

From the point of view of designers, windows are the most vulnerable points in the building envelope. Through them there is intense energy exchange between the room and the environment.

Calculation of window area is carried out according to the methods given in SNiP (“Building Norms and Rules”). They provide illumination standards for various types of premises, corresponding coefficients and formulas.

In a simplified way, the area of ​​light openings can be calculated based on the recommended ratios between the areas of windows and floors. These data were not taken out of thin air, but were obtained on the basis of many years of data analysis in various regions of the world.

The relevant information was summarized and compiled into easy-to-use tables.

For example, for civil buildings in the climatic conditions of the middle zone at an altitude not higher than 800 m above sea level, with slight shading by nearby buildings, the ratio of glazing area to floor area will be as follows:

• living rooms - 1/8–1/6;
• kitchens and corridors - 1/10–1/8;
• staircases - 1/14–1/10;
• classes and audiences - 1/4–1/3;
• playing and dining rooms in kindergartens - 1/4–1/3;
• hotel rooms - 1/8–1/6;
• library reading rooms - 1/6–1/5;
• offices and laboratories of the research institute - 1/7–1/5;
• administrative premises - 1/10–1/6;
• sports gymnasiums - 1/6–1/5;
• gyms - 1/5–1/4;
• medical offices - 1/7–1/5;
• hospital wards - 1/7–1/6;
• restaurant halls - 1/8–1/6;
• trading floors of stores - 1/8–1/6.

Clarifying calculation

However, these are not the only guidelines for calculating window sizes. There are other quite working methods for determining the area of ​​light openings using special formulas, in which one of the most important parameters is also the floor area.

Today, different countries use several different methods for calculating the KEO (daylight coefficient):

• protractor method
• grid method
• ray method
• luminous flux utilization factor method
• analytical methods

They all give similar results.

How to correctly calculate the area of ​​walls with a complex surface

Not all rooms have a strict rectangular shape. Buildings often contain intricate architectural elements that complicate calculations.

How to calculate the square footage of walls minus openings

When determining the exact scope of work, we subtract the sizes of windows and doors from the total number of square meters of the walls of the room. To do this, measure the width and height of the window along the edge of the frame, and the dimensions of the door along the edge of the frame.

By multiplying the length and width of the openings, we get the size that needs to be subtracted.

We proceed in the same way if we need to exclude stoves, fireplaces, and radiators from the calculated square footage of a room.

The room has a window 2.5 m × 1.5 m and a door 0.9 m × 2.1 m.

What is a square meter

First you need to decide what a square meter is. People who did not study mathematics well at school still sooner or later face the problem of counting the amount of building materials. Therefore, a square meter is the main reference point when determining the area of ​​a room.

If you draw a square (this is a geometric figure with equal sides), and the side is equal to 100 cm, then when multiplied by 100 we get the number 10000 cm. This means that the size of this figure is 10000 cm2. It could be simpler. Calculate in meters: 100 cm is 1 m. We apply the formula for calculating the area - we multiply the two sides, that is, we multiply 1 by 1, we get 1 m. This means that the size of the square is 1 sq.m.

Calculating the area of ​​the walls of a house using a calculator

Special programs, which include a construction calculator in the online version, will greatly facilitate the calculations.

To see how many square meters the walls are minus the openings, just select the geometric shape of the room and enter the indicators:

• width;
• length;
• height;
• number of openings;
• sizes of windows and doors.

The construction calculator will calculate the amount of finishing materials needed for your renovation.

Floor or ceiling area

The ceilings and floors in an ordinary apartment are the same. How to calculate square meters? Very simple. If the room is an attic, then there is no ceiling - there is only a floor and walls.

• Stage No. 1. Measure the length of the room and write down the resulting number on paper. If the number is an integer, then we simply write the number. For example, 5 (m). If the number is greater than 5 but less than 6, then you will have to remember decimal fractions and write, for example, 5.5 (m).
• Stage No. 2. Measure the width of the room and write it down in the same way. For example - 3m.
• Stage No. 3. Now you need to multiply these two numbers. Example: 5 x 3 = 15m. So, the floor area is 15 square meters. m. Consequently, the size of the ceiling will also be 15 square meters. m. Write this number separately and circle it with a pen.

Tips and tricks

It must be remembered that the geometric parameters of buildings can rarely be ideal. Therefore, to determine exact values, it is better to take measurements in several places and then derive the arithmetic average. For example, when calculating the area of ​​a room based on the walls, it is better to measure the length along the ceiling, baseboard and in the middle of the vertical plane. Height - in the corners and the middle of the wall along a plumb line.

To calculate the perimeter in the presence of many protrusions and niches of different shapes, you need to lay a cord along all the elements, then measure it with a tape measure.

Having calculated the exact parameters, you can go to the store for building materials. It is better to show diagrams with dimensions to the sales consultant. A specialist will help you calculate the consumption of materials, taking into account overlaps, selection of wallpaper patterns or losses when cutting tiles.

Measuring tools

To correctly calculate the total quadrature you will need a tool such as:

• construction tape of at least 5 meters;
• pen or pencil;
• calculator;
• building level or similar device with a scale;
• stepladder or stool;
• a sheet of paper for notes.

Prepare everything you need to measure walls. You can also use special services available on the Internet, however, their accuracy is not always correct, and for maximum accuracy it is better to do everything yourself.
Before calculating the area of ​​the walls of the room, it is necessary to provide free access to them and move furniture away to allow unhindered movement. This is very important, because from the initial data obtained from the measurement, we obtain the total volume of the room, as well as the square footage of the ceiling and floor.

For maximum accuracy, it is recommended that before taking measurements, mark a straight line slightly above the level of the baseboards using a building level or any other long and level strip. Next, the tape measure is applied horizontally to the surface above the baseboard and the data obtained is recorded on paper. The next step is to measure the distance from the floor to the ceiling, again leaning the tape measure against the wall.

Don't forget to write down all the data you receive.

If the room has the shape of a rectangle, then to obtain the total area of ​​the room it is enough to multiply the resulting width by the length. For example, if a wall is 5 meters long and 3 meters wide, then multiply 5 by 3 to get 15 squares.

Similarly, we measure each wall and add the resulting values ​​into one total. For example, in a rectangular room there are 2 walls of 15 square meters and 2 of 8, we add these values ​​15x2=30, 8x2=16, 30+16=46. In total, the total surface area of ​​the walls of the room was 46 squares.

How to calculate window area

For multi-apartment multi-storey buildings, as well as for standard individual construction projects, the window area in a living room is a parameter calculated by specialists in advance, and for the apartment owner it does not matter, since it already meets all norms and standards. But for developers who build their own housing from scratch, according to their own design, window area is as important a parameter as the grade of cement or the strength of concrete. The calculated glazing area helps not only to provide the correct lighting in the room - it also means the correct arrangement of furniture, and the correct calculations of the floor beam of the opening, and much more.

Window area calculation table

Standards according to GOST

For window opening standards, there is a State Standard regulation numbered 11214-86. This standard also determines the dimensions for balcony doors. In accordance with this GOST, the width of windows varies from 870 to 2670 mm, height from 1160 to 2060.

The table below will introduce you to typical window sizes according to GOST.

The usual window width is calculated taking into account the purpose of the building, for each room and room, its location and dimensions, since the level of natural sunlight, depending on the geographical location, determines the degree of illumination.

Standard frames are made according to GOST, since it is important for windows to provide the necessary amount of daylight in the house.

Thus, the dimensions for a two- and three-leaf window manufactured in accordance with GOST should be 1300X1400 mm and 2050X1400 mm .

the value of these characteristics :

Based on generally accepted standards, the window area comes from the area of ​​the room, and the size of the house itself. What does the size of the opening affect? First of all, on the glazing of the window, how many sashes there will be and the shape itself.

As you can see, choosing window sizes is a rather labor-intensive task. It is necessary to prevent damage to the frame and materials. The best solution is to hire a measurer to do everything professionally. It’s better to overpay, but then enjoy well-placed and not crooked windows, than to suffer with the sizes.

Watch this video about the optimal size of a window opening:

Standards and rules

There are practical and scientifically proven standards that determine the calculation of window area, which affects other parameters of the room. Below are the fundamental extracts from several SNiPs for developers:

1. SNiP 31-01-2003 determines the ratio of glazing to the total floor area for kitchen and living areas in the house - they must maintain a range of 1:5.5 - 1:8. In addition, a broader understanding of this parameter is indicated here: in low-rise buildings for the upper floors with inclined glazing (attics, attics, terraces), the ratio of the window light opening to the floor of the room should be ≥ 1:10. Also, the glazing area may vary depending on natural light and the characteristics of the window itself;
2. SNiP 31-02-2001 defines the requirements for the flow of natural light through window openings in kitchens and living rooms. The optimal value of the natural light flux will be ensured by the ratio of glazing to floor area as 1:8, for attics and attics with inclined windows - as 1:10, but not less;
3. SNiP 2.08.01-89 and SNiP 23-05-95 standardize the requirements for a larger group of premises for natural lighting. These are living and kitchen premises, bathrooms without sewerage, corridors and halls not directly connected to residential premises, staircases, corridors and passages in “tram” type buildings, public residential premises. In all of the listed premises, the ratio of the glazing of window openings to the floor area should be ≤ 1:5.5, taking into account that the minimum ratio is allowed as 1:8, and for attics and attics with inclined windows - 1:10.

An example of a quick calculation of glazing area
When calculating the glazing area to the floor area, we start from the following necessary steps:

1. It is necessary to calculate the area of ​​the window opening and determine the dimensions of the frame in order to find out the volume of light flux and glazing area;
2. It is necessary to decide on the size and pattern of the window frame if it is not possible to use a standard pattern;
3. It is necessary to work out drawings of each window indicating the exact dimensions if it is impossible to use a standard window. At the same time, the minimum glazing area is regulated by lighting standards - from SP 31-110-2003 to MGSN 2.06-99;
4. The ratio of room glazing to floor area should not depend on the climatic and geographical region of the residential property, as well as on the orientation of the building to the cardinal points;
5. When planning a room using windows to illuminate secondary rooms with additional light, the glazing area is calculated taking into account all areas of the rooms that will be illuminated by these light openings.

What are the rules abroad?

The standards for the size and area of ​​windows in a house abroad are not so categorical, in terms of no more and no less. Actually, it’s not entirely clear why not more and not less. If these limits are set from the point of view of energy saving or protecting residents from heat stroke in the summer, then such measures are not enough. Simply limiting the area will not protect you from troubles.

In developed countries, issues such as the maximum or minimum size of glazing are considered solely from the point of view of architecture and aesthetics. Over the millennia of the formation of various architectural styles, a certain stereotype has developed regarding the relationship between the facade and the size of windows. In this case, not only the size, but also the location of the window on the facade relative to the axis is of great importance. All this, combined with the size of the building, the height of the ceilings, not just the floor area, the external decoration and style of the building, determines the size, number, shape and location of windows. There is no other approach.

Therefore, in Norway there can be houses covered with turf. With small, barely noticeable windows on the shore of the fjord, and frame, half-timbered houses with high narrow windows. Or frame and all-glass cottages. Today, everything depends on the style, aesthetics and architectural solution of the author and owner. But such glazing is always accompanied by appropriate measures to ensure comfort for residents. Chameleon glass (photochromic) or low-emission glass is used in combination with measures to insulate the walls and provide highly efficient heating devices.

Additional energy sources are used, solar energy - all this allows the use of any glazing with any area. You only need to pay attention to the glass skyscrapers of Toronto or Chicago to understand that standards for the size and area of ​​windows in a house for countries with developed construction technologies do not exist. There are questions of expediency and style that guide them.

How to calculate the main window dimensions

When designing a home, the minimum area of ​​windows and their installation location are determined. Based on this, it is possible to calculate more accurate and specific parameters for each window of each room in order to find out the glazing area. When making calculations, it is customary to determine the maximum window height for a particular room in order to take advantage of optimal natural lighting conditions.

Taking into account the fact that the height of the window sill is 70-90 cm, and in houses with central heating 80-90 cm, and the upper lintel of the window should be no higher than 15-25 cm from the ceiling, it is easy to calculate the maximum height of the window and apply the light ratio to it parties - these calculated parameters will comply with the requirements of SNiP.

Calculation of window height from floor and ceiling

According to SNiP, with a total glazing area corresponding to 10-12% of the floor area of ​​the room, a minimum amount of natural light will enter it. In this case, the optimal width of the window opening is considered to be corresponding to 55% of the width of the room.

The aspect ratio of the window plays more of a visual significance than a constructive one. Also, the correctly chosen aspect ratio makes it more comfortable to use the transoms. Therefore, the correct proportions are usually taken as standard ratios, for example, 8:13. There are computer programs to calculate window sizes; you can also use an online calculator.

In addition, there are rules that must be followed when making any calculations. For example, before calculating the parameters of the window and luminous flux, it is assumed that for one living space the angle of incidence of natural light through the glazing should be 18-30 0, and the glazing area should be in the range of 14-17% of the total floor area in the room .

When calculating the parameters, it is necessary to take into account neighboring buildings - the angle of incidence of the natural flow of light depends on the height of the window opening and the proximity of buildings adjacent to the dwelling. The natural flow of light will decrease as the distance between houses decreases, and vice versa. The same applies to the angle of incidence of illumination - the higher the nearby buildings, the higher the angle of light flux.

An example of finding design points

In building design, a window is considered the most vulnerable surface in terms of heat and energy exchange, therefore any standard calculations require minimizing the size of the window, which leads to a decrease in the natural light flux through the glazed area. To avoid a conflict between the desire to increase lighting and heat losses, the corresponding SNiPs have been drawn up and are in effect. Using the same recommendations, coefficients and formulas, designers carry out calculations of illumination and natural light fluxes for different rooms.

Emergency lighting angle calculation

The calculation results in the form of window aspect ratios are given below. These are examples for civil objects located in central Russia at an altitude of ≤ 800 meters above sea level, with slight shading by neighboring objects:

1. Premises intended for living, including hotel rooms, restaurant and retail premises: 1:8-1:6;
2. Food preparation areas and corridors: 1:10-1:8;
3. Staircases and cages: 1:14-1:10;
4. Educational, children's and playrooms: 1:4-1:3;
5. Reading and sports halls: 1:6-1:5;
6. Scientific classrooms and laboratories: 1:7-1:5;
7. Administration premises: 1:10-1:6;
8. Medical office premises: 1:7-1:5;
9. Premises for patients – wards: 1:7-1:6;

Orientation of the building to the cardinal directions
But these results of glazing areas and aspect ratios of openings, calculated using formulas, can still be considered approximate, since a separate calculation of natural lighting for each window in the room is required.

Sizes of window openings and room illumination

In frame buildings with strip-cut walls and strip lighting, the width of window openings determines the width of individual inserts along the axes of the supporting structure of the frame.

When designing buildings, the dimensions of window openings are set taking into account the required illumination of the premises, depending on their purpose, size, natural light in specific geographical conditions, the light characteristics of the window for a given ratio of the dimensions of the room and the window opening, the light transmittance of the window block, etc.

The area of ​​window openings as a percentage of the area of ​​the room is regulated by the “Building Norms and Rules” (SNiP P-A862) and is determined by the formula. SNiP P-A862 gives the normalized value of k.e.o. in the main premises of residential and public buildings located north of 45° and south of 60° northern latitude, taking into account the mandatory regular cleaning of glass at least 2 times a year for rooms with insignificant emissions of dust, smoke and soot, and four times for rooms with significant emissions.

When buildings are located south of 45° north latitude, the normalized value of k.e.o. multiplied by a factor of 0.75, and when the buildings are located north of 60° north latitude by a factor of 1.2.

For example, with side lighting in buildings located north of 45° and south of 60° north latitude c.e.o. it is 0.5 for residential premises, 1 in locker rooms and medical offices, 1.5 in school classrooms and laboratories, classrooms, assembly and sports halls, group rooms of kindergartens, dressing rooms and laboratory rooms of medical institutions, wards of maternity hospitals and 2 in hospital operating rooms.

SNiP allows deviations of ±10% of the calculated values ​​of k.e.o. (average or minimum) from the normalized value when assigning the sizes of window openings. SNiP provides the values ​​of the total light transmittance of the light opening t0. These values ​​take into account the shading of the opening by supporting structures, the material and design of the binding. For example, for single binding t0 = 0.4, for double binding T0 = 0.25, for double binding t0 = 0.3.

Thus, the light transmittance of a window opening, under all equal conditions, is affected by the distance between the panes and the number of panes. Naturally, with an increase in the number of glasses and the distance between them, the light transmittance of windows worsens due to the absorption and refraction of part of the light rays. The reflectivity of walls, ceilings and floors is taken into account by the coefficient G (SNiP). With medium tones of wall decoration G = 3.0.

The effect on the illumination of the room of the darkening of window openings by opposing buildings is taken into account by the coefficient k. In new construction, if the required gaps between buildings are observed, the darkening coefficient is practically equal to 1 and can not be taken into account. The light characteristic of windows c0 depends on the ratio of the width and depth of the illuminated room B and on the ratio of its depth to the elevation H of the upper edge of the window above the conventional working plane (for example, in educational premises) or the floor (in residential premises), the value of the light characteristic c0 is given in SNiP (with a window sill height of no more than 1.2 m).

Using these values ​​in accordance with the data of the illuminated room, it is possible to determine the value of the light characteristic of the window opening with rounded relationships between the width and length of the room and between its depth and the elevation of the upper edge of the window. To more accurately determine the intermediate values ​​of the light characteristics of a window, the interpolation method should be used.

Window luminous characteristic value

Having determined the values ​​of the normalized coefficient of natural illumination em, the total coefficient of light transmittance To, the coefficient of influence of reflected light Г and the light characteristic of the window r0 for a given room (in the absence of darkening of the window by opposing buildings) and substituting these values ​​into the transformed formula, we obtain the required area of ​​the window opening.

Popular questions when calculating windows

How to calculate correctly?

Despite the availability of multifunctional calculators, they are limited in several parameters, especially when calculating windows and window frames. If you order it entirely in non-standard sizes, you must take into account additional problems that may arise during operation.

In other words, non-standard windows require additional parameters, because of this you will have at least one question: “how to calculate the weight?”

Metal-plastic window with two movable sashes

Formula for calculating window weight

An accurate weight is necessary to determine the load that will act on the hinges. If this is missed, the window may bend under its own weight, especially in areas of movable elements and sashes.

These parts should not weigh more than 60 kg, so the average is around 50 kg. In the photo you can see the main point that is affected by the mass of the sash.

Movable sash window hinge

In order to calculate the required weight, it is necessary to take into account 3 standards used by most manufacturers:

1. Thickness 4 mm;
2. Weight of 1 m2 of single-chamber glass with frame 25 kg;
3. Weight of 1 m2 double-glazed window with frame 35 kg.

Based on these data, we can calculate the mass based on the dimensions using a very simple formula: multiply the window area by the standard 1 m2 of the selected glass unit. Don't know how to calculate the window area? You just need to multiply the width by the height.

For example, you chose a single-chamber double-glazed window with a height of 140 cm and a width of 90 cm. Let’s find out the area by converting the indicator into meters: 1.4*0.9= 1.26 m2 – the area of ​​our window. Now we calculate the mass: 1.26 * 25 = 31.5 - we get the required weight.

Basic parameters of a plastic window

For fixed-type windows, you do not need to carry out a weight calculation, since they do not have movable parts.

Accurate area calculations

The larger the structure, the more difficult it will be to accurately measure it. Therefore, the question of how to calculate the window area in square meters on a large scale is very relevant. But everything is not as difficult as it seems at first glance:

1. First, you need to divide the entire structure into the metal-plastic sections of which it will consist.
2. After this, you need to find out the area of ​​​​each section, including both fixed and movable windows.
3. Then all you have to do is add up the entire area, and you will get the total area of ​​the entire structure.

Large metal-plastic windows

Formula for calculating square meters

To calculate the area, you need to apply the formula per square meter A XB, where number A is the length of one side, and number B is the length of the second side. They can be the same if the shape of the floor or wall is square.

Most often, it is not square, but rectangular, that is, number A will have one value, and number B will have another. They will need to be multiplied in your head, or using a multiplication table, or on a calculator. And the resulting number will be the area that will need to be covered with paint or something else.

It happens that the shape of the floor is not standard, but, for example, trapezoidal. Then it’s more difficult, especially for those people who don’t know what a triangle is (this also exists in nature). To calculate the size of a trapezoid, you must first calculate the area of ​​the rectangle in the middle, then the size of each triangle on the sides, then add these three numbers. Isn't it easier to immediately call a team of workers? Let them think about how to calculate the square meters of the room.