Ratio of window area to room area

Comfort in any room is largely determined by its lighting. The best source is sunlight, which can be obtained from windows. With proper glazing, the room will not only be light, but also warm and cozy.

According to SNiP, in order to ensure a minimum amount of light penetrating into the room, the glazing area is about 10–12.5% of the total. In addition to the linear dimensions of the window, their ratio is also important. For better visual perception, it is recommended to bring the width to height ratio as close as possible to the parameters of a harmonic rectangle, say, 80 to 130.

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.

Calculation of the area of light openings when insulating the facade

To calculate the insulation of the facade, it is necessary to know the area of the openings. The area of the facade minus the area of the facade openings, we get the insulation area of the house. In the last article we talked about how to calculate the insulation area of a façade. But without information about all the openings on the facade, it will not be possible to perform the calculation.

Why do you need information about the area of openings when insulating a facade?

I'll start from the very beginning:

– in order to insulate a house, you need to know the cost of insulating the facade, then it will be possible to plan financial resources. – you can determine the cost of insulating the facade of a house by drawing up an estimate, calculating the cost of work and the cost of materials. – to draw up an estimate, the volume of work required for which an estimate can be drawn up. – in order to obtain the scope of work, it is necessary to take measurements of the facade planned for insulation.

After taking measurements of the facade, we make calculations and obtain data for drawing up an estimate. This is why the area of the window and door opening on the facade of the house is needed.

What basic and incidental data do we get when calculating the area of the openings of the façade of a house?

1.The height and width of the opening is necessary for the opening area. The area of the opening is subtracted from the total area of the façade of the house. As a result of simple calculations, we obtain the insulation area of the facade.
2. The height and width of the opening allows you to determine the number of linear slopes in meters. We will need this data to calculate the number of perforated corners.
3. We need the width of the slope to calculate the amount of slope insulation in m2. To calculate the material - polystyrene foam, primer, glue, mesh, dowels, it is better to have a figure in m2.

Why is it necessary to separately calculate the area of slopes in m2?

Because on slopes, as a rule, the thickness of the insulation is less than the main insulation of the facade.

What determines the thickness of insulation on slopes?

The thickness of the insulation on slopes depends on the distance between the slope of the opening itself and the edge of the window or door frame. You can’t put 50 mm thick insulation on a slope if this distance is only 30 mm. If you install 50 mm thick insulation, the foam will extend onto the glass or double-glazed window. Agree, it will not be very nice.

4. The width of the window and the width of the slope are necessary for preliminary calculation of the cost of window sills. Why pre-calculation? Because the most error-free option is to order ebbs when the foam is brought to the window, but before the slopes are installed. It is then that you can measure the exact dimensions. The human factor is always present, so it is better not to order window sills until this moment. Making castings, as a rule, does not take much time, but sometimes it is simply not possible to remake them. And if it is possible, then traces of the previous fold will be visible, which is also not beautiful.
5. The easiest way is to make and fill out a table after measuring the facade - a table of openings.

You should have the following information about each door or window opening: – window height – window width – slope width – thickness of insulation on the slope – ebb width

The easiest way to make this table is in Excel and it will look approximately like this in the photo.

It is very convenient when the openings on the façade are marked with numbers in order. And in the table opposite the number there is all the information on this opening. Because if there are a lot of sizes on a piece of paper, then you can confuse the values and make an error in the calculations.

Having received the total area of the façade openings, the area of the slopes, and the linear meters of the slopes, we use this data to draw up an estimate for insulation. Now you can move on to drawing up the estimate for façade insulation.

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.

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.

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 calculate the dimensions of walls and ceilings

To do this, you just have to remember your favorite school and geometry lessons. It is known that the area of a rectangle is its length multiplied by its width. The area of window and door openings, as well as places where plastering is not required, is taken from the result obtained.

For example, it is planned to renovate a room 3 meters wide, 4 meters long, let the ceiling height be 2.8 meters. The room has a window measuring one and a half meters by one meter and a door measuring two by one meter. Let's calculate the area (S) of the walls:

S long wall 4 m X 2.8 m = 11.2 m 2
S short wall 3 m X 2.8 m = 8.4 m 2
Total S of all four walls 11.2 m 2 X 2 + 8.4 m 2 X 2 = 39.2 m 2
S window opening 1.5 m X 1 m = 1.5 m 2
S doorway 2 m X 1 m = 2 m 2
Total S openings 1.5 m2 + 2 m2 = 3.5 m2
S wall plaster 39.2 m2 - 3.5 m2 = 35.7 m2
Ceiling S will be 3 m X 4 m = 12 m 2

In this case, we separately calculate S of the ceiling, which will be 3 m X 4 m = 12 m 2. Why do we count the ceiling area separately? Plastering the ceiling is a rather specific and not as popular service as plastering the walls. Plus, work on ceilings costs more than work on walls.

If you have an unusually shaped room, calculating the area will be a little more difficult. You may need to remember the formulas for the area of a triangle, circumference, etc. To simplify the task, special programs are used - plaster area calculators. This application can be installed on your phone, tablet or computer.

How to calculate the area of windows so that the house is not dark

When designing and constructing a residential building, you must be guided by the contents of SanPiN 2.1.2.2645-10. According to this regulatory act, all residential premises are required to have light openings in the external walls of the building. The number of windows in living rooms and kitchens must be such that the coefficient of natural light is not lower than 0.5. Insolation standards are established by regulatory documentation taking into account:

geographical latitude of the object's location;
calendar period;
functionality of the premises;
planning zone of the city.

At least one of the rooms of a 1-3 room apartment must have a level of illumination that meets established standards. When the apartment consists of more than 4 rooms, then satisfactory lighting should be in 2 or more rooms.

Based on building rules, you can calculate the square footage of windows for each room in a residential building:

Measure the floor area of each individual room.
Determine the minimum permissible glazing area, calculating 10 - 12.5% of the resulting floor area of the room.

When designing light architectural elements, it is necessary to take into account that the final footage of the glazing will be less than the opening left. This is explained by the presence of a light-proof box at any window, which is used to install the window and fasten the glass inside the window block.

It is generally accepted that the most comfortable for a person’s well-being is the total width of the windows of the room, which is 55% of the width of the room. If there is only one window opening, then it should be located in the center of the longest outer wall.

The level of insolation can be adjusted by placing the structural element vertically: the higher the opening relative to the floor, the greater the illumination. This condition is true when there are no tall buildings or trees in the immediate vicinity that impede the penetration of sunlight.

At the design stage, when calculating the glazing surface, it is necessary to focus on the rules for thermal protection of buildings. According to these rules, the glazing coefficient of the facade in a residential building does not exceed 18%, taking into account the heat transfer resistance of light and ventilation openings.

It is permissible to install skylights in private residential buildings, which are windows of complex and non-standard geometric shapes. The area of such light openings should not exceed 15% of the floor area. In the case where the skylight is mounted in an attic room, the glazing area can be maximum equal to 10% of the room's area.

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Double-glazed windows: bulky or energy-saving

Of course, in a residential area, the double-glazed window must be sealed, and in our area it must also be double-glazed.

For houses whose owners are concerned about energy saving, double-glazed windows with improved thermophysical characteristics are offered - with argon filling and heat-reflecting coating (the so-called I-glass and K-glass). According to manufacturers, they can reduce heat loss by 30-40% compared to conventional ones, and in some cases, make do with a lightweight single-chamber design instead of a bulky and heavy two-chamber one. Heat-reflective coatings work, as they say, on two fronts - retaining heat in winter and preventing the room from turning into a greenhouse under direct sunlight.

One of the areas of application for improved single-chamber double-glazed windows is large glazing surfaces. But thin window glass is not an option in this case - in translucent structures, thick glass is used - from 8 mm. A square meter of such sheet glass weighs 20 kg, and the total weight of structures consisting of double-glazed windows of frame and frame profiles can be calculated in tons; their design requires precise calculations, and installation requires special equipment and highly qualified performers.

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.

Houses of various series

In addition to buildings with characteristic names that allow them to be attributed to a specific period of construction, there are a number of standard series. These buildings were erected at different times and have their own distinctive features. We invite you to get to know them.

Ships 1Lg-600

Design documentation for this series was developed in the 60s in Leningrad with a focus on the northern capital. Here they mainly used the standard project. Construction began in 1969 and continued until 1989. The number of floors was selected individually. Buildings with 5 to 15 floors were erected. The panel walls of houses in this series have brick inserts. Thanks to them, it was possible to dampen the strength of the coastal wind quite well.

The dimensions of the window blocks are as follows:

View	Height, mm	Width, mm
Tricuspid	1420	2690
Tricuspid	1130	2380
Balcony block	2200	1800 with door width 700 mm

Episode 121

Another series that has been actively used in the construction of large-panel residential buildings since 1970. It has not lost its relevance today. The number of floors is mainly 3–9. However, in some regions you can also find 12-story buildings. The house uses reinforced concrete floors. The main disadvantage of this series, which most residents complain about, is the low level of sound insulation. Despite this, the project does not lose its relevance.

Large-panel buildings. Their story began in 1970. And it's still not over. Number of floors: from 3 to 9. But there are also rare 16-story buildings. The main disadvantage is poor sound insulation.

The dimensions of the window blocks are as follows:

View	Height, mm	Width, mm
Bivalve	1410	1450
Tricuspid	1420	1700
Balcony block	2050	1440

Episode 137

The construction of houses in this series was completed relatively recently. They were actively erected from 1974 to 2015. The number of floors was chosen mainly from the range 9 – 16. However, 18-story buildings were also erected. Most often, series 137 was built in St. Petersburg. However, the project was also implemented in Orel and Volgograd. The apartments have a separate bathroom. The kitchen area is 8 - 15 square meters.

The dimensions of the window blocks are as follows:

View	Height, mm	Width, mm
Bivalve	1420	1150
Tricuspid	1420	1700
Tricuspid	1440	2050
Balcony block	2140	1880 with door width 680

Series 504

The standard project was implemented from 1969 to 2001. More often, the choice in its favor was made in Chelyabinsk and St. Petersburg. By their nature and area, apartments in houses of this series are an improved version of Brezhnevka apartments. Large panels are used to build walls. Number of floors: 5, 9, 10 and 12. Parquet is provided as flooring. Residents can take advantage of spacious loggias. A distinctive feature of residential buildings of the 504 series is their good sound and heat insulation, which is a significant advantage compared to other projects.

The dimensions of the window blocks are as follows:

View	Height, mm	Width, mm
Bivalve	1410	1450
Tricuspid	1420	1700
Balcony block	2140	1180 with door width 680

Series 600.11

Improved version of 1Lg-600. A distinctive feature is the L-shaped shape of the kitchen window. Due to the changes made, it became possible to install an air conditioner with standard dimensions in the window vent. The number of floors in the house differs. Selected from 4 – 11. The houses were built over a long period: from 1982 to 2015.

The dimensions of the window elements are as follows:

View	Height, mm	Width, mm
Bivalve	1410	1450
Kitchen	1440	1850
Window	550	870
Tricuspid	1420	1700
Balcony block	2140	1880 with door width 680

Series 602

The houses were erected during the reign of Brezhnev. Includes 5 or 9 floors. Found in St. Petersburg, Riga and Naberezhnye Chelny. Active construction took place from 1966 to 1982. Elevators and garbage chutes were already provided inside. There were loggias along the side ends. Polymer, glass slabs, and ceramics were actively used as decorative materials for wall decoration.

The dimensions of the window blocks are as follows:

View	Height, mm	Width, mm
Bivalve	1530	1450
Tricuspid	1530	2230
Balcony block	2070	2030 with door width 680

Series 606

Most often, such high-rise buildings were built in St. Petersburg from 1966 to 1974. Each floor has 6–7 apartments, depending on the number of entrances. Bathrooms are separate. There is parquet on the floor. Expanded clay concrete was used to construct the walls. The ceiling height in the apartments is 2.7 m.

The dimensions of the window blocks are as follows:

View	Height, mm	Width, mm
Bivalve	1530	1490
Tricuspid	1520	2080
Balcony block	2070	2030 with door width 680

Rectangular premises

To get started, you will need a measuring tape and a calculator.

The most common option is a rectangular room; even a schoolchild knows the formula for finding its square:

S = a* b (length times width)

For example, a room with parameters 4*6 m has an area of 24 sq. m.

It's another matter if you have built-in furniture or a fireplace. If you do not plan to remove them during the renovation, and lay the flooring of an apartment or private house around them, then it is also worth calculating their sizes and subtracting them from the total value .

However, this option is only suitable for “cosmetic repairs” of the surface; if you screed the floor of an apartment or your house or install new joists, you will definitely have to dismantle everything.

Work on mistakes

The range of products and components for the installation of metal-plastic and wooden windows includes many hundreds of items and today will remain outside the scope of our brief review. But in any case, high-quality fittings and qualified installers are not something you should skimp on.

Particular care is required when installing windows in a wooden house that is subject to shrinkage: they are mounted in special casing structures that eliminate pressure on the frame.

If the profile is deformed, it will most likely not be possible to repair the window; you will have to order and install a new one.

Such a hidden defect, such as the absence of the argon filling of a glass unit promised by the manufacturer, can only be detected as a result of a thermal imaging examination. But, by the way, the manufacturer is not always to blame for this - a microcrack in the glass is enough for the structure to lose its tightness.

Irregularly shaped rooms

It will be much more difficult to calculate a polygonal room with your own hands. Often the layout of houses has niches, rounded elements, and triangular corners.

Technical passport of the apartment

Calculating the floor area in such cases requires first dividing it into simpler elements. For example, you have an L-shaped room - the easiest way is to divide it into 2 rectangles, calculate their sizes separately and add them up.

L-shaped room plan

Calculate the sizes of triangular elements

If the second part of the room is not located at a perpendicular angle with respect to the main part, then between the 2 rectangles there is also a triangle, the sides of which converge at right angles.

You need to additionally calculate its quadrature using the formula and add it to the total value:

For example, if a triangle has legs of 3.5 and 4.5 m: S = (3.5*4.5)/2 = 7.9 m².

Another example of how to calculate the floor area of a room with a sloping corner is shown in the photo with all dimensions.

Scheme of a bathroom with a beveled corner

To calculate the quadrature of such a room, you need to first calculate the quadrature of the rectangle, and then for the triangle, and subtract its dimensions from the total value.

Here is an example of a calculation based on the values specified in the diagram:

Rectangle = 2.5 * 1.75 = 4.4 m2.
Beveled triangular corner = (0.57*0.57)/2 = 0.2 m2.
Final size = 4.4 – 0.2 = 4.2 m2.

If the triangle is not right-angled, then its calculation is done using Heron’s formula:

Heron's formula for a triangle

The symbol "p" is semi-perimeter. For example: we have a triangular shaped floor whose sides are 5, 6 and 7 meters.

Let's do the calculation for this figure:

Find the semi-perimeter: (5+6+7)/2 = 9.
We substitute the values into the formula: √(9 * (9-5) * (9-6) * (9-7)) = √(9 * 4 * 3 * 2) = √216 = 14.7 m2.

Calculation of rounded elements

Often, old houses have such a rounded shape near a window, or on a balcony combined with a room.

All formulas for calculating plane figures

To do this, first calculate half of the protruding part of the circle and add it to the main rectangular part.

Formula for calculation:

S = πR 2 /2, where π – 3.14, R 2 – radius of the circle squared.

For example, we have a semicircular protruding balcony with a radius of 1.5 m.

Let's substitute the numbers into the formula and find its quadrature:

S = 3.14 * 1.5 2 / 2 = 3.5 sq. m.

Room area in square meters

It’s not difficult to calculate, you just need to remember the simplest formulas and also take measurements. For this you will need:

Roulette. It’s better with a lock, but a regular one will do.
Paper and pencil or pen.
Calculator (or count in a column or in your head).

A simple set of tools can be found in every household. It’s easier to take measurements with an assistant, but you can do it yourself.

First you need to measure the length of the walls. It is advisable to do this along the walls, but if they are all filled with heavy furniture, you can take measurements in the middle. Only in this case, make sure that the tape measure lies along the walls, and not diagonally - the measurement error will be less.

Rectangular room

If the room is of the correct shape, without protruding parts, it is easy to calculate the area of the room. Measure the length and width and write it down on a piece of paper. Write the numbers in meters, followed by centimeters after the decimal point. For example, length 4.35 m (430 cm), width 3.25 m (325 cm).

How to calculate the area of a room

We multiply the found numbers to get the area of the room in square meters. If we look at our example, we get the following: 4.35 m * 3.25 m = 14.1375 sq. m. In this value, usually two digits are left after the decimal point, which means we round. In total, the calculated square footage of the room is 14.14 square meters.

Irregularly shaped room

If you need to calculate the area of an irregularly shaped room, it is divided into simple shapes - squares, rectangles, triangles. Then they measure all the required dimensions and make calculations using known formulas (found in the table just below).

Before calculating the area of the room, we also make changes. Only in this case there will be not two, but four numbers: the length and width of the protrusion will be added. The dimensions of both pieces are calculated separately.

One example is in the photo. Since both are rectangles, the area is calculated using the same formula: multiply the length by the width. The found figure must be subtracted or added to the size of the room - depending on the configuration.

Room area of complex shape

Using this example, we will show how to calculate the area of a room with a ledge (shown in the photo above):

We calculate the quadrature without the protrusion: 3.6 m * 8.5 m = 30.6 sq. m.
We calculate the dimensions of the protruding part: 3.25 m * 0.8 m = 2.6 sq. m.
Add up two values: 30.6 sq. m. + 2.6 sq. m. = 33.2 sq. m.

There are also rooms with sloping walls. In this case, we divide it so that we get rectangles and a triangle (as in the figure below). As you can see, for this case you need to have five sizes. It could have been broken differently by putting a vertical rather than a horizontal line

It doesn't matter. It just requires a set of simple shapes, and the way to select them is arbitrary

How to calculate the area of an irregularly shaped room

In this case, the order of calculations is as follows:

We consider the large rectangular part: 6.4 m * 1.4 m = 8.96 sq. m. If we round, we get 9.0 sq.m.
We calculate a small rectangle: 2.7 m * 1.9 m = 5.13 sq. m. Round up, we get 5.1 sq. m.
Calculate the area of the triangle. Since it is at a right angle, it is equal to half the area of a rectangle with the same dimensions. (1.3 m * 1.9 m) / 2 = 1.235 sq. m. After rounding we get 1.2 sq. m.
Now we add everything up to find the total area of the room: 9.0 + 5.1 + 1.2 = 15.3 square meters. m.

The layout of the premises can be very diverse, but you understand the general principle: divide it into simple shapes, measure all the required dimensions, calculate the square footage of each fragment, then add everything up.

Formulas for calculating the area and perimeter of simple geometric shapes

Another important note: the area of the room, floor and ceiling are all the same measurements. There may be differences if there are some semi-columns that do not reach the ceiling

Then the quadrature of these elements is subtracted from the total quadrature. The result is the floor area.

Wall area

Separately, it is worth noting that the area of the walls cannot be found by the area of the floor, as some people try to do. The thing is, to find the square footage of the floor you only need 2 values: width and length, and to calculate the walls you also need to know their height.

Therefore, you will first have to calculate the perimeter of the walls and multiply it by the height of the ceilings.

For example, you considered the floor dimensions to be 5*6 meters, and the room has a height of 2.5 meters.

We calculate the perimeter of the walls: (5+6)*2 = 22 m.
S = 22*2.5 = 55 sq. m.

Note! Don't forget to subtract the square footage of door and window openings after calculating the walls. Although they are sometimes not specifically taken into account in order to preserve the supply of materials.

Window to floor ratio

The size and number of windows in living rooms and kitchens depend on the specific room.

The instructions in SNiP 31-01-2003 for multi-apartment residential buildings recommend maintaining the window area to floor area in the range from 1:5.5 to 1:8. On the upper floors it is permissible to make windows with a ratio of at least 1 to 10 to the floor.
For private houses, SNiP 31-02-2001 applies; for every 8 squares of floor there must be at least 1 square of natural light source. On attic floors this ratio can be at least 1:10.

Percentage of window openings and floor

Note! Also for residential buildings there are standards for the ratio of artificial lighting to the floor surface, described in SNiP 2.08.01-89 and 23-05-95.

For example, if your floor is 4*5 meters, the light opening should be from 2 to 3.6 square meters. To find out the glazing area to the floor area, divide the square footage of the room by a multiplier from SNiP suitable for your conditions (from 5.5 to 10). (see also the article Features of floor lighting)

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:

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;
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;
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:

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;
It is necessary to decide on the size and pattern of the window frame if it is not possible to use a standard pattern;
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;
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;
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.

Geometric coefficient when determining luminous flux
Requirements for luminous fluxes for a room with natural light, but additionally illuminated artificially, are determined by the area of the window opening, which should be:

In bathrooms - 0.5 of the total floor area of the room;
In showers and bathrooms - 0.25 of the total floor area of the room;
In halls, vestibules and corridors - 0.16 of the total floor area of the room;
In entrance rooms with natural light, the window opening area can be within 0.4-0.5 of the floor area of the room.

Also:

If there are windows in a long corridor, any place on the wall opposite the window should not be closer to the window than 750 cm;
If a long corridor is illuminated only by a window at the end of the room, then the distance of the farthest point of the wall from the window should not be greater: for northern regions 20 meters, for southern regions - 25 meters;
If the corridor is illuminated at both ends by natural light, then its length should not exceed 55 meters.

Standard window size for residential premises

In a private house

Standards for window openings exist to regulate light in private homes and beyond.

The characteristics of window openings are based on what the room is intended for, but the following is also provided:

the ability of a window package to transmit light;
geography;
dimensions of the building;
degree of suitable lighting.

Based on building codes, we calculate window standards. In addition, they are designed for cleaning twice a year, and for areas with poor ecology - 4 times a year .

Now they also provide for the number of glasses in the package and the distance between them - for each customer the refractive index of the beam will not be calculated, and the illumination will decrease.

If we take single-leaf windows, then their usual width and height vary from 470X470 mm to 1470X870 mm. Naturally, everything here depends on the dimensions of the opening.

Let's look at double- and triple-hung windows. Windows with two sashes vary from 570X1170 mm to 1470X1470 mm. Window openings with three sashes vary from 1170X1770 mm to 1470X2070 .

Do you know how to make plastic window slopes with your own hands? Details are in this article.

In the apartment

Now let's look at the standards of windows in an apartment panel building. It all depends on the type of house:

for “brezhnevka” the dimensions of a double-leaf window are 1300x1400 mm, with three sashes - 2100x1400 mm;
for the “new layout”: with two doors 1460X1430 mm, with three - 1780X1430 mm;
“Stalinka” is characterized by T-shaped windows, its dimensions can be 1500X1900 mm, 1250X1800 mm and 1080X1800 mm;
for “Khrushchev”: double-leaf window 1208X1340 mm, three-leaf window - 2040X1500 mm;
for the “Czech”: with two doors 1300X1400 mm, with three - 1760X1400 mm.

Window calculator

How to calculate the cost of metal-plastic windows using a calculator?

— the metal-plastic window opens

- the window opens and tilts for ventilation

2. In the lower left corner of the plastic window calculator, you can select the type of double-glazed window. A single-chamber double-glazed window consists of two glasses and an air chamber between them. Double-glazed window - three glasses and two chambers between them. The price of a metal-plastic window equipped with an energy-saving single-chamber double-glazed window is similar to the price of a window with a single-chamber double-glazed window, since energy-saving coating comes as a gift. An energy-saving single-chamber double-glazed window is inferior to a double-chamber one in terms of sound insulation, but is identical in terms of thermal insulation.

3. You can set the size of PVC windows using the sliders of the window calculator by pulling them or enter them manually in the appropriate cells. Dimensions are given in millimeters. There is no need to specify a unit of measurement.

Window sizes are limited by maximum and minimum dimensions. If you want to calculate plastic windows of smaller or larger sizes, select the appropriate window configuration. For example, the maximum dimensions of a double-hung window are 1800 x 1700 mm. In order to calculate a window with large dimensions, it is necessary to select three-leaf windows.

The most common sizes of plastic windows in typical houses:

Khrushchev - two-leaf window: width - 1300 mm; height - 1340 mm, windows with three sashes: width - 2050; height - 1340 mm

Brezhnevka - two-part windows: 1500 x 1500 mm, three-part windows: 2100 x 1500 mm

Windows in the 137 series - double-leaf: 1150 x 1420 mm, three-leaf: 1700 x 1420 mm.

4. This section will help you find out the remaining sizes of plastic windows and doors in houses of standard construction, the Stalin era and the old building.

5. After you have chosen the configuration of the plastic window and the dimensions to calculate the cost of the window, its installation and finishing, you need to click on the Calculate button located in the upper right corner of the window calculator interface.

6. If you encounter any difficulties during the calculation process, we will be happy to calculate the cost of metal-plastic windows and doors by phone

(812) 677-32-65 or you can send a request for a cost calculation by email.

Results of price calculation using a window calculator

If you are interested in the cost of a plastic window without installation and finishing work, the price is shown in the right block, top line. The price of the window includes all the main elements: white PVC profile (German Rehau profile, Euro line or Korean LG Hausys profile, L-600 line), double-glazed window, set of fittings (German fittings Roto NT or Siegenia AUBI), handles, hinge plugs, stand profile. The price of the window does not include fastening elements - anchor plates and bolts, as well as additional accessories such as comb opening limiters, window care kits, handles with locks.

Installation 1 - right side of the window calculator (block with prices)

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:

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.
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.

The most ideal proportions are considered to be a rectangle with a width to height ratio of 80x130 cm. Such windows are easy to use and do not create unnecessary load on the fittings .

Calculation of the price of plastic windows

Customer Reviews

2014-12-30 00:00, Kostroma

2014-12-25 11:38:00,

Teachers and parents of students of the Palace of Children and Youth Creativity

Parents of students and the teaching staff of the Palace of Children and Youth Creativity express their deep gratitude to the Window Technologies company and in particular to the team of installers #40; Kirill and Roman #41;, who on December 19, 2014 replaced windows in the branch of the Teremok Palace on B. Vorobyovskaya Street 10 /34. The team worked very quickly and carefully! Thus, the high professionalism of the craftsmen and coherence in their work brought a lot of pleasure and a lot of joy to all of us! Thank you very much. We congratulate your company on the upcoming 2015 and wish you PROSPERITY.

Price matters

Our goal is to create a quality product at a reasonable price. Our own production and expansion of partnerships allows us to achieve minimum purchasing prices. In addition, we are constantly working to optimize technological processes and increase labor productivity. That's why our windows are not only high-quality, but also cheap, accessible to almost everyone. Especially considering the installment plan.

If you are interested in the benefits that you will receive with plastic windows, you can calculate the cost of your new windows directly on the website. This can be done easily and conveniently using our window calculator. Select your home type, window size, and window configuration, then click Next. You will receive an approximate figure - an indicator that we are really cheap.

Please note that the website displays the preliminary price of plastic windows. The calculation will be 100% correct only after our specialist has measured the window openings

It’s easy to sign up for a free measurement - fill out the form on the “Call a Master for a Measurement” website. Our managers will contact you and agree on a time convenient for you.

Can't find the best option? Don't know which installation to choose (standard or MAX technology)? Any other questions? Call! In any of our offices or by calling the hotline 8 800-2008-608 you can always get qualified advice.

Hurry up to order a new window while seasonal discounts are valid! Your savings – from 2900 rubles!

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 :

the area of this room;

required degree of illumination;

architectural features of the structure and the premises itself.

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:

Insolation requirements

Artificial lighting, even of the highest class, cannot compare with natural lighting. Lack of sunlight can quickly affect your health.

SNiP, regulating this area, imposes quite stringent requirements.

If shielding control systems grow with or without sufficient subject knowledge, complications are inevitable

It is also important to note that the external solar control elements driven by the motor and system, particularly the irradiation, screens and awnings, are equipped with automatic protection against destruction. In daylight conditions, these devices are parked in a resting position, provide no sun protection, and cannot be controlled by local user controls

It is therefore advisable to consider such eclipse of additional internal shading elements.

In multi-apartment residential buildings, the ratio between the area of living quarters and kitchens and the area of window openings should be no more than 1:5.5 and no less than 1:8.
For private houses, the floor area of all living rooms and kitchens and the area of window openings should be in a ratio of 1:8.
In attic rooms with a sloping roof, a ratio of 1:10 is allowed.

This means that the size of the window opening, based on the proportion, will be equal to: 12/8 = 1.5 square meters. m. These are the minimum window sizes that are acceptable in such a room.

Daylight significantly influences the perception of the interior and affects the psyche and health of the person in it

Pay special attention to the choice of shape and size of windows and other transparent structures and their placement. This should already be associated with the project documentation

Another situation arises when a window design is given and the interior must be adapted to the lighting conditions.

Many body functions, as well as the human psyche, depend on natural daylight. Natural light and the regular daily cycle of changes are closely related to human biorhythm. The lack of light is depressing, whether we want to admit it or not. Well-chosen artificial lighting can alleviate the effects and consequences of a lack of natural light for people, but cannot replace it equally. If a person is to feel comfortable in a room, they must be in good condition, which means that the space where they stay longer must be provided with a reasonable amount of daytime natural light.

Windows are necessary to provide sufficient lighting during the day.

Rice. 1. Types and overall dimensions of windows in residential buildings (USSR and Russia)

Rice. 2. Types and overall dimensions of balcony doors in residential buildings (USSR and Russia)

Visual well-being is mainly related to the intensity of lighting without significant distractions. The quality of lighting also affects the direction of light in space, the color rendering of the interior and the color of light. However, this is a very general solution that does not take into account the orientation from different sides, the shape of the room, external shading elements - balconies, loggias, the proximity and height of surrounding buildings, plants or terrain. However, the owner's subjective feelings must enter into these figures. The shape, size and placement of windows must be decided by the architect because other factors such as the layout, character of the house or proportions and its overall architectural design also come into play in the design.

Ratio of window area to room area

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Healthy
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Window sizes. Insolation of premises

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Healthy
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Window sizes. Insolation of premises

The design of an individual country house in terms of window openings takes into account SNiP for the necessary insolation of residential premises. The dimensions of hinged structures for natural lighting are now no longer standard ( standard window size is 150x150cm

). Depends on the purpose of the premises and the wishes of the Customer. Window manufacturers will make almost any glazing with some limitations.

Recommended insolation of residential premises in northern latitudes is +20% (this includes central Russia). That's why houses with second light are popular in our country. The sizes and proportions of windows may vary. However, the thermal resistance of window glass is much inferior to solid wood walls. Due to the large glazing, it is hot in summer and cold in winter. The rule must be followed: the total area of double-glazed windows is no more than 25% of the area of the building wall in which they are installed.

Architecture

SNiP 01/31/2003 Residential multi-apartment buildings 9.13. The ratio of the area of light openings to the floor area of living quarters and kitchens

should take no more than 1:5.5 and no less than 1:8; for upper floors with light openings in the plane of inclined enclosing structures - at least 1:10, taking into account the lighting characteristics of windows and shading by opposing buildings.

SNiP 02/31/2001 Single-apartment residential buildings 8.9. Natural lighting should be provided in living rooms and kitchens. The ratio of the area of light openings to the floor area of living quarters and kitchens

must be at least 1:8. For attic floors it is allowed to take this ratio at least 1:10.

SNiP 2.08.01-89* Residential buildings 1.3*. Living rooms, kitchens, unsewered restrooms, entrance vestibules (except for those leading directly to apartments), staircases, common corridors in corridor-type residential buildings, as well as public spaces in dormitories and residential buildings for the elderly and families with disabilities should have natural lighting. Natural lighting should be taken in accordance with the requirements of SNiP 23-05-95. At the same time, the ratio of the area of light openings of all living rooms and kitchens of apartments and dormitories to the floor area of these premises

, as a rule, should not exceed 1:5.5. The minimum ratio must be at least 1:8; for attic floors, when using attic windows, a ratio of 1:10 is allowed. .

. Actually the question: During the examination of a residential building project, the expert had complaints regarding light openings and floor area for specific premises

.
An attempt to explain that the specified requirements should be taken into account for premises (living and kitchen) within the apartment
was not successful. “We don’t know how to read the rules.”

Which is correct?? I am ready to listen to the opinion of the respected community. Maybe someone will have some clarification on this issue.

Sorry, we got distracted. The question is whether these ratios of opening areas to floor area should be applied for individual rooms or checked in total for living areas and the kitchen of an entire apartment. We designed precisely based on the total ratios for apartments (old edition of SNiP 2.08.01). Otherwise, the layout “climbs out” onto the facade: small room - small window, large room - large window. Arch is ready to shoot himself.

Unfortunately, it is natural for me that insolation and illumination of premises are independent calculations and influence the indicated ratios indirectly. It turns out that even the future arrangement of furniture (a wardrobe along the wall) should influence the facade, but the floor area of the room has changed. The expert is trying to link this to heating engineering. But everything here is so far-fetched that I don’t even want to discuss it.

Posted by lee : small room - small window, large room - large window

- isn't this logical?

Message from r_am : For some reason, it always seemed to me that the architecture of the facade should reflect the internal structure of the building (including the planning one). Or at least what a reflection is is a good technique

I don’t argue about the “good reception”. But in general, not sure??

Message from r_am : isn't this logical?

It is useless to look for logic here. Just as a counter pass: why does the area of light openings depend on the area of the floor?? Maybe it would be more logical to dance based on the volume of the room??

depending on the volume - it’s more logical, but after all, this is an apartment building. Here, in my opinion, there is quite enough space (all rooms are the same height and most likely within the range of 2.7-3.3 m).

In general, our standards have a similar provision (without specifying the general

area of the rooms), but in practice there were projects where it was clearly violated. Somehow they passed an examination.

Message from lee : We designed based on the total ratios for apartments (old version of SNiP 2.08.01). Otherwise, the layout “climbs out” onto the facade: small room - small window, large room - large window. Arch is ready to shoot himself.

Well, you give it. Why not count for the whole house or a microdistrict?

Comrades. What should you consider when determining the area of window openings? (Question) Q

excerpt from SNiP SNiP 01/31/2003 “Residential multi-apartment buildings” 9.13 The ratio of the area of light openings to the floor area of residential premises and kitchens should be taken no more than 1:5.5 and no less than 1:8; for upper floors with light openings in the plane of inclined enclosing structures - at least 1:10, taking into account the lighting characteristics of windows and shading by opposing buildings.

excerpt from SP 23-102-2003 NATURAL LIGHTING OF RESIDENTIAL AND PUBLIC BUILDINGS window calculations should be made according to formulas and graphs

When determining the window area according to these standards, the values are obtained different. Question: what should we be guided by?
Which norms are MORE IMPORTANT?
The same question arises when calculating windows for administrative premises. (calculation of windows for them is only in SP 23-102-2003, and window area ratios are not specified anywhere else)

I read back in SP 23-102-2003 that combined lighting can be used, the QUESTION is in what ratio can combined lighting be used (the ratio of artificial to natural? if there is such a thing at all).

A specific example: an office building, according to natural lighting standards, the depth of the premises is 6 m, but it needs 11 m, is this possible with combined lighting?

Consumer protection

It is believed that norms and standards are designed to protect consumers from low-quality housing. But is it? And does GOST cope with the functions that are assigned to it? And is such comprehensive standardization necessary? Everything that we now use to protect ourselves from cold or heat came to us from the West. A new type of profile for window systems, low-emissivity glass, blinds, roller blinds, mini-blinds. All, at first outlandish, technology and attributes of protection from the sun and cold came to us from there, without any norms and standards, GOSTs and TUs. The main standards used in these countries are convenience, quality and comfort. In Germany, France, Denmark, and England, when installing sealed PVC window systems, it is mandatory to install climate control valves. And this is enshrined in law, and not a minimum or maximum window size, which is of no interest to anyone. If the windows do not meet the clients' requirements, no one will buy a house or an apartment. And this is enough for the architectural product to always be harmonious in its decisions, including in matters of glazing. And it must be said that not everything is going smoothly with the provision of housing there either. Not everyone can afford expensive penthouses. However, standardization, which certainly exists in these countries, and is no less highly developed, still does not interfere with market issues, which determine which windows, in which region and with which energy-saving equipment should be designed. And the standards they use are much broader and more comprehensive. Moreover, they are international and equally understandable in Australia, Singapore, and Japan. and Germany. But they relate to completely different areas of engineering and technology, which provide the priorities of international trade.

Standard parameters and properties of window systems

To make plastic window structures, you will have to contact a construction company, or if you want to save money, go directly to the manufacturer, and they will offer you a standard range.

As a rule, the sizes of windows in a frame wooden house are as follows:

Single leaf (height 400-1470 mm, width 400-870 mm);
Double-leaf (height 570-1470 mm, width 870-1470 mm);
Three-leaf (height 1170-1470 mm, width 1770-2070 mm).

Standard sizes of windows in a house from manufacturers in the Russian Federation.
Choosing a larger sash size is not entirely safe: glass is a fragile material, and it requires a special binding. If you are planning a balcony on the second floor, then the door dimensions will be standard (height 2100-2200 mm, width 700-900 mm).

All of the listed window sizes are produced by most construction companies, and if you want to make an exclusive order, the window set will be significantly more expensive.

Standard parameters of window structures are designed for the same type of openings in multi-storey panel buildings, and the demand for them is quite high, but construction companies carry out orders for individual sizes much less often. Therefore the cost is much higher. When designing, take into account the future location of all furniture and its dimensions.

Distance from window to floor

A typical standard window should be located at a height of 80 to 90 cm from the floor : this provides a good view for both a sitting and a standing person, and you can place a desktop or other piece of furniture under the window sill. The upper edge of the block is usually located at a height of 220 to 230 cm from the floor.

Special requirements apply to windows in the premises of a wooden bath: a bath room does not require good lighting, but the preservation and retention of heat is very important. Following these requirements, a standard bath window in a steam room is no larger than 600×600 mm, and in a relaxation room the window can be made larger, for example 1000×1200 mm.

Maximum size of plastic window structure

When choosing large individual window structures with increased sash area, you need to know the existing requirements set out in special building regulations:

The area of the entire structure should not be more than 6 square meters. meters. Otherwise, it may not withstand the wind load, and in unfavorable weather conditions the glass unit may crack and crumble into fragments.
You should not ignore safety rules: weather conditions in different regions of Russia are changeable and unpredictable. Large blocks should have partitions, and the area of the doors should not be higher than 2.8 square meters. m. The maximum permissible size of the sashes is 110×240 cm. When designing window openings, keep in mind that a large structure can quickly fail. A metal-plastic profile with a two-chamber (three-chamber) double-glazed window will be very heavy, and due to the large weight, the fittings will soon begin to sag and sag. In this case, the sash will wear out and it will begin to creak; using such a design will be inconvenient and even more unsafe. If you decide to install an arched window, then its radius should not be less than 35 cm. The requirements for large sashes will be the same as for conventional turning systems.

Why is it important to know the window area?

Calculation of the area of ​​light openings when insulating the facade

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

Glazing parameters

How experts calculate glazing area

Floor or ceiling area

Clarifying calculation

How to calculate the dimensions of walls and ceilings

How to calculate the area of ​​windows so that the house is not dark

Double-glazed windows: bulky or energy-saving

Sizes of window openings and room illumination

Houses of various series

Ships 1Lg-600

Episode 121

Episode 137

Series 504

Series 600.11

Series 602

Series 606

Rectangular premises

Work on mistakes

Irregularly shaped rooms

Calculate the sizes of triangular elements

Calculation of rounded elements

Room area in square meters

Rectangular room

Irregularly shaped room

Wall area

Popular questions when calculating windows

Formula for calculating window weight

Accurate area calculations

The final stage

Window to floor ratio

Standards and rules

Standard window size for residential premises

In a private house

In the apartment

Window calculator

How to choose?

Calculation of the price of plastic windows

Standards according to GOST

Insolation requirements

Ratio of window area to room area

Architecture

Consumer protection

Standard parameters and properties of window systems

Maximum size of plastic window structure

Calculation of the area of light openings when insulating the facade

How to calculate the area of windows so that the house is not dark