Specific heat conductivity of materials. Comparison of the thermal conductivity of various building materials and the calculation of the wall thickness

The construction of a cottage or country house is a complex and time-consuming process. And to ensure that the future structure has stood for several decades, it is necessary to comply with all norms and standards when it is erected. Therefore, each stage of construction requires accurate calculations and the quality performance of the necessary work.

One of the most important indicators in the construction and finishing of the structure is the thermal conductivity of building materials. SNIP (building codes) provides a full range of information on this issue. It is necessary to know that the future building is comfortable for living both in summer and in winter.

Perfect warm home

The comfort and economy of living in it depend on the structural features of the structure and the materials used in its construction. Comfort consists in creating an optimal microclimate inside regardless of external weather conditions and ambient temperature. If the materials are selected correctly, and the boiler equipment and ventilation are installed according to the norms, then in such a house there will be a comfortable cool temperature in summer and warm in winter. In addition, if all materials used in construction have good thermal insulation properties, then energy costs for heating the premises will be minimal.

The concept of heat conduction

Thermal conductivity is the transfer of heat energy between directly contacting bodies or media. In simple words, thermal conductivity is the ability of a material to conduct a temperature. That is, getting into some medium with a different temperature, the material begins to take the temperature of this medium.

This process is of great importance in construction. So, in the house with the help of heating equipment the optimum temperature (20-25 ° C) is maintained. If the temperature in the street is lower, then when the heating is turned off, all the heat from the house after a while will go out and the temperature will drop. In the summer, the opposite situation occurs. To make the temperature in the house lower than the street, you have to use air conditioning.

Coefficient of thermal conductivity

The loss of heat in the house is inevitable. It occurs constantly when the temperature outside is less than in the room. But its intensity is a variable. It depends on many factors, the main among which are:

• Area of ​​surfaces involved in heat exchange (roof, walls, floors, floor).
• The index of thermal conductivity of building materials and individual building elements (windows, doors).
• The difference between the temperatures on the street and inside the house.
• And others.

To quantify the thermal conductivity of building materials use a special coefficient. Using this indicator, you can easily calculate the necessary insulation for all parts of the house (walls, roof, floors, floors). The higher the thermal conductivity of building materials, the greater the loss of heat. Thus, for the construction of a warm house it is better to use materials with a lower value of this value.

The coefficient of thermal conductivity of construction materials, as well as of any other substances (liquid, solid or gaseous), is denoted by the Greek letter λ. The unit of its measurement is W / (m * ° C). In this case, the calculation is carried out on one square meter of a wall one meter thick. The temperature difference here is taken to be 1 °. Practically in any construction manual there is a table of thermal conductivity of building materials, in which you can see the value of this coefficient for various blocks, bricks, concrete mixtures, wood species and other materials.

Determination of heat loss

There is always a loss of heat in any building, but depending on the material, they can change their value. On average, heat loss occurs through:

• The roof (from 15% to 25%).
• Walls (from 15% to 35%).
• Windows (from 5% to 15%).
• The door (from 5% to 20%).
• Sex (from 10% to 20%).

To determine heat loss, a special thermal imager is used, which determines the most problematic places. They are highlighted in red. Less heat loss occurs in the yellow zones, then - in green. Zones with the least loss of heat are highlighted in blue. A definition of the thermal conductivity of building materials should be carried out in special laboratories, as evidenced by the quality certificate attached to the products.

Example of heat loss calculation

If we take, for example, a wall made of a material with a coefficient of thermal conductivity of 1, then with a temperature difference on both sides of this wall of 1 °, the heat loss will be 1 W. If wall thickness   take not 1 meter, but 10 cm, then the losses will amount to 10 watts. In the event that the temperature difference is 10 °, then the heat loss will also be 10 W.

Let us now consider, with a concrete example, the calculation of the heat loss of an entire building. The height of it will be 6 meters (8 with a ridge), width - 10 meters, and length - 15 meters. For ease of calculations, we take 10 windows with an area of ​​1 m 2. The temperature inside the room will be considered equal to 25 ° C, and on the street -15 ° C. We calculate the area of ​​all surfaces through which heat loss occurs:

• Windows - 10 m 2.
• The floor is 150 m 2.
• The walls are 300 m 2.
• The roof (with ramps along the long side) is 160 m 2.

The formula for the thermal conductivity of building materials makes it possible to calculate the coefficients for all parts of the building. But it is easier to use already prepared data from the directory. There is a table of thermal conductivity of building materials. We consider each element separately and determine its thermal resistance. It is calculated by the formula R = d / λ, where d is the thickness of the material, and λ is the coefficient of its thermal conductivity.

Floor - 10 cm of concrete (R = 0.058 (m 2 * ° C) / W) and 10 cm of mineral wool (R = 2.8 (m 2 * ° C) / W). Now add these two indicators. Thus, the thermal resistance of the floor is 2.858 (m 2 * ° C) / W.

Similarly, the walls, windows and roof are considered. Material - cellular concrete (aerated concrete), thickness 30 cm. In this case, R = 3.75 (m 2 * ° C) / W. The thermal resistance of the formation window is 0.4 (m 2 * ° C) / W.

The following formula allows us to determine the loss of thermal energy.

Q = S * T / R, where S is the surface area, T is the temperature difference between the outside and inside (40 ° C). Calculate the heat loss for each element:

• For the roof: Q = 160 * 40 / 2.8 = 2.3 kW.
• For walls: Q = 300 * 40 / 3.75 = 3.2 kW.
• For windows: Q = 10 * 40 / 0,4 = 1 kW.
• For the floor: Q = 150 * 40 / 2,858 = 2,1 kW.

Further, all these indicators are summarized. Thus, for this cottage, the heat loss is 8.6 kW. And to maintain the optimum temperature, boiler equipment with a capacity of at least 10 kW will be required.

Materials for external walls

To date, there are many wall building materials. But the most popular in private housing construction is still using building blocks, bricks and wood. The main differences are the density and thermal conductivity of building materials. Comparison makes it possible to choose the golden mean in the density / thermal conductivity relation. The higher the density of the material, the higher its bearing capacity, and consequently, the strength of the structure as a whole. But at the same time, its thermal resistance is lower, and as a result, energy costs are higher. On the other hand, the higher the thermal resistance, the lower the density of the material. Less dense, as a rule, implies the presence of a porous structure.

To weigh the pros and cons, you need to know the density of the material and its thermal conductivity. The following table of the thermal conductivity of building materials for walls gives the value of this coefficient and its density.

Wall insulation for walls

If there is insufficient thermal resistance of external walls, different heaters can be used. Since the values ​​of the thermal conductivity of building materials for insulation can be very low, most often a thickness of 5-10 cm will be enough to create a comfortable temperature and microclimate in the premises. Widely used today are materials such as mineral wool, expanded polystyrene, expanded polystyrene, foam polyurethane and foam glass.

The following table of the thermal conductivity of building materials used for the insulation of external walls gives the value of the coefficient λ.

Features of the use of wall heaters

The use of insulation for exterior walls has some limitations. This is primarily associated with a parameter such as vapor permeability. If the wall is made of a porous material, such as aerated concrete, foam concrete or expanded clay, then it is better to apply mineral wool, since this parameter is almost the same for them. The use of expanded polystyrene, polyurethane foam or foam glass is possible only if there is a special ventilation gap between the wall and the heater. For a tree, this is also critical. But for brick walls, this parameter is not so critical.

Warm roofing

Insulation of the roof allows you to avoid unnecessary overruns when heating the house. For this, all types of insulation, both sheet format and sprayed (foam polyurethane) can be used. In this case, do not forget about the vapor barrier and waterproofing. This is very important, because the wet insulation (mineral wool) loses its properties in terms of thermal resistance. If the roof is not insulated, then it is necessary to thoroughly insulate the floor between the attic and the last floor.

Floor

Warming of the floor is a very important stage. It is also necessary to apply vapor barrier and waterproofing. As a heater used more dense material. It, accordingly, has a higher coefficient of thermal conductivity than roofing. An additional measure for warming the floor can serve as a basement. The presence of air layer allows to increase the thermal protection of the house. And the equipment of the system of a warm floor (water or electric) gives an additional source of heat.

Conclusion

When building and finishing the facade, it is necessary to be guided by accurate calculations for thermal losses and take into account the parameters of the materials used (thermal conductivity, vapor permeability and density).

Thermal conductivity of the materials from which the building is built is an important indicator, on the value of which depends on how well the heat in your house will be saved. Especially it is worth paying attention to the heat-insulating properties of products used for the erection of external walls, since they protect the interior of the structure from heat loss in winter. Than this indicator is lower, the longer the heat is stored, and, consequently, the costs for heating the housing are reduced.

  Heat conduction table

Thermal conductivity is the ability of matter to conduct heat and take the temperature of its surrounding objects. The unit of measurement of the coefficient of heat index is the value W / (mK). The table below shows the thermal conductivity of the main wall materials, which are most often used in the construction and insulation of facade walls.

The coefficient of any magnitude can be influenced by the humidity of the air, since its values, although insignificantly, vary with the season and climatic conditions. Where the density of the material is not indicated in the table, the value is not decisive in terms of heat conduction.

The thermal conductivity of a material is determined by its chemical composition, degree and nature of porosity, as well as by the conditions under which heat transfer takes place by humidity and air temperature. Materials having a fibrous and layered structure of the structure can conduct heat differently. For example, wood products with a cross section of fibers have a greater degree of thermal conductivity than with a longitudinal section.

Since air transmits very little heat (0.023W / m-0 C), porous materials with air cells have less thermal insulation properties. But if the product is saturated with moisture, its thermal conductivity increases, because water conducts heat faster than air, 25 times.

  Comparative characteristics

Based on the data in the table, taken from the SNIP from 2003, porous wall materials, such as foam concrete and aerated concrete (see) based on lime and arbolite, have the least thermal conductivity. But the cellular structure has a big drawback: pores are quickly saturated with moisture from the environment, as a result of which their thermal conductivity increases.

In addition, after being absorbed by moisture, after several cycles of freezing and thawing, the porous structures begin to lose their strength, which leads to the destruction of the material. To maintain the frost-resistance of aerated concrete and foam blocks, use a moisture-resistant finish for outdoor work.

The walls of the house made of brick masonry have a greater thermal conductivity, so to better save heat, their thickness should be about 40 or even 50 cm. Such consumption leads to a rise in the cost of the structure, so in recent times, brick is increasingly being used as facing material.

They are lined with walls from light blocks, protecting them from the destructive effects of moisture. In addition, the brick house looks beautiful and does not require additional finishing. If desired, between the masonry and concrete blocks, a heater is attached, which increases the safety of heat in the house.

  Types of heaters

Of insulation with a lower thermal conductivity have expanded polystyrene and extruded polyurethane foam. These are hard, brittle materials, produced in plates, and having a cellular structure. But it must be taken into account that as the density of the material structure increases, its ability to transmit heat also increases.

Mineral heaters in addition to good heat preservation, have excellent sound insulation properties: they extinguish sounds, not allowing them to enter the room.

Minvate is produced in the form of plates or in rolls. Plates are encased walls, roof, floor. The roll insulation is suitable for sheltering water supply and heating pipes.

The construction of each object is better to begin with the design of the project and careful calculation of the heat engineering parameters. Accurate data will provide a table of thermal conductivity of building materials. Proper construction of buildings contributes to optimal climatic parameters in the room. A table will help to choose the right raw materials, which will be used for construction.

Thermal conductivity of materials affects the thickness of walls

Thermal conductivity is an indicator of the transfer of heat energy from heated objects in a room to objects with a lower temperature. The heat transfer process is performed until the temperature indicators are equalized. To denote thermal energy, a special coefficient of thermal conductivity of building materials is used. The table will help you see all the required values. The parameter denotes how much heat energy is passed per unit area per unit time. The more this designation, the better heat exchange will be. When building buildings it is necessary to use a material with a minimum value of thermal conductivity.

The coefficient of thermal conductivity is a value that is equal to the amount of heat passing through a meter of material thickness per hour. Use of this characteristic is necessary to create a better thermal insulation. Thermal conductivity should be taken into account when selecting additional insulation structures.

What influences the indicator of thermal conductivity?

Thermal conductivity is determined by such factors:

• porosity determines the heterogeneity of the structure. With the passage of heat through such materials, the cooling process is insignificant;
• increased density affects the close contact of particles, which contributes to faster heat transfer;
• increased humidity increases this figure.

Using the values ​​of the coefficient of thermal conductivity in practice

Materials are represented by structural and heat-insulating varieties. The first type has great heat conductivity. They are used for the construction of floors, fences and walls.

Using the table, the possibilities of their heat exchange are determined. In order for this indicator to be sufficiently low for a normal microclimate in the room, walls made of certain materials must be particularly thick. To avoid this, it is recommended to use additional heat-insulating components.

Indicators of thermal conductivity for finished buildings. Types of insulation

When creating a project, all methods of heat leakage must be considered. It can go out through the walls and the roof, as well as through the floors and doors. If you do the wrong design calculations, you will have to be content with only the heat energy received from the heaters. Buildings built from standard raw materials: stone, bricks or concrete must be additionally insulated.

Additional insulation is carried out in frame buildings. In this case, the wooden frame imparts rigidity to the structure, and the insulation material is laid in the space between the posts. In buildings of brick and cinder block insulation is made outside the structure.

When choosing heaters, it is necessary to pay attention to such factors as humidity level, influence of elevated temperatures and type of construction. Take into account certain parameters of thermal insulation:

• the heat conductivity index affects the quality of the heat-insulating process;
• moisture absorption is of great importance in the insulation of external elements;
• the thickness affects the reliability of insulation. A thin insulation helps to maintain the useful area of ​​the room;
• inflammability is important. Quality raw materials have the ability to self-extinguish;
• thermostability reflects the ability to withstand temperature changes;
• environmental friendliness and safety;
• soundproofing protects from noise.

• polyurethane foam is known for such qualities as incombustibility, good water-repellent properties and high fire resistance;
• extruded polystyrene in the process of further processing. Has a uniform structure;

• penofol is a multi-layer insulating layer. The composition contains expanded polyethylene. The surface of the plate is covered with foil to ensure reflection.

For bulk insulation, bulk materials can be used. These are paper granules or perlite. They have resistance to moisture and to fire. And from organic varieties, you can consider fiber from wood, flax or cork. When choosing, pay special attention to such indicators as environmental friendliness and fire safety.

Note!   When constructing insulation, it is important to think about installing a waterproofing layer. This will avoid high humidity and increase resistance to heat transfer.

Table of thermal conductivity of building materials: characteristics of indicators

Table of thermal conductivity of building materials contains indicators of various types of raw materials, which is used in construction. Using this information, you can easily calculate the thickness of the walls and the amount of insulation.

How to use the table of thermal conductivity of materials and heaters?

The table of resistance to heat transfer of materials presents the most popular materials. Choosing a certain version of thermal insulation is important to take into account not only physical properties, but also characteristics such as durability, price and ease of installation.

Did you know that it's easiest to install foam-isoizol and polyurethane foam. They are distributed over the surface in the form of foam. Such materials easily fill the cavities of the structures. When comparing hard and foam options, it should be noted that the foam does not form joints.

The values ​​of heat transfer coefficients of materials in the table

When making calculations, you need to know the coefficient of resistance to heat transfer. This value is the ratio of the temperatures on both sides to the amount of heat flow. In order to find the heat resistance of certain walls and the heat conduction table is used.

All the calculations you can do yourself. For this purpose, the thickness of the interlayer of the thermal insulator is divided by the thermal conductivity coefficient. This value is often indicated on the packaging, if it is insulation. Materials for the house are measured by yourself. This concerns the thickness, and the coefficients can be found in special tables.

The coefficient of resistance helps to choose a certain type of thermal insulation and the thickness of the material layer. Information on the vapor permeability and density can be seen in the table.

With the correct use of tabular data, you can choose a quality material to create a favorable indoor microclimate.

Thermal conductivity of building materials (video)

1. Heat loss at home

The choice of thermal insulation, wall finishing options for most customers - developers is a difficult task. Too many contradictory problems need to be solved simultaneously. This page will help you in all this to understand.
At present, the heat-saving of energy resources has acquired great importance. According to SNIP II-3- 79 * "Construction Heat Engineering", resistance to heat transfer is determined based on:

• sanitary and hygienic and comfortable conditions (the first condition),
• energy saving conditions (second condition).

For Moscow and its area, the required thermal resistance of the wall on the first condition is 1.1 ° С · m. sq. m. / W, and according to the second condition:

• for a house of permanent residence 3,33 ° С · м. sq. m. / W,
• for a seasonal residence 2,16 ° С · m. sq. m. / W.

1.1 Table thickness and thermal resistance of materials for the conditions of Moscow and its region.

1.2 Table of the minimum reduced resistance to the heat transfer of external structures in the homes of the Moscow Region.

From these tables it can be seen that the majority of suburban housing in the suburbs do not meet the requirements for heat savings, even the first condition is not observed in many newly built buildings.

Therefore, selecting a boiler or heating appliances only for the indicated in their documentation ability to heat a certain area, you claim that your house is built with strict consideration of requirements SNiP II-3-79 *.

From the above material follows the conclusion. For the correct choice of boiler output and heating appliances, it is necessary to calculate the actual heat loss of the premises of your house.

Below we show a simple methodology for calculating the heat loss of your home.

The house loses heat through the wall, the roof, strong heat emissions go through the windows, heat also leaves the ground, significant heat losses can occur in the ventilation.

The heat losses mainly depend on:

• differences in temperatures in the house and on the street (the greater the difference, the higher the losses)
• heat-protective properties of walls, windows, ceilings, coatings (or, as the enclosing structures say).

Fencing structures resist heat leakage, so their heat-shielding properties are evaluated by a value called resistance to heat transfer.
The heat transfer resistance shows how much heat will pass through a square meter of the enclosing structure for a given temperature difference. It can also be said on the contrary, what kind of temperature difference will occur when a certain amount of heat passes through a square meter of fences.

R =? T / q,

where q is the amount of heat that loses a square meter of the enclosing surface. It is measured in watts per square meter (W / m2); ΔT is the difference between outdoor and room temperature (° C), and R is the resistance to heat transfer (° C / W / m² or ° C · m. Sq. / W).
When it comes to multi-layer construction, the resistance of the layers simply folds. For example, the resistance of a wall of wood lined with brick is the sum of three resistances: a brick and wooden wall and an air gap between them:

R (sum) = R (wood) + R (ref.) + R (b.p.).

1.3 Temperature distribution and boundary layers of air during heat transfer through the wall

Calculation for heat loss is carried out for the most unfavorable period, which is the most frosty and windy week of the year.

In construction manuals, as a rule, indicate the thermal resistance of materials based on this condition and the climatic region (or outdoor temperature) where your house is located.

1.3 Table   - Resistance of heat transfer of various materials at ΔT = 50 ° С (Т нар. = -30 ° С, Т internal = 20 ° С.)

1.4 Table - Thermal losses of windows of various designs

at ΔT = 50 ° С (Т нар. = -30 ° С, Т internal = 20 ° С.)

As can be seen from the previous table, modern double-glazed windows can reduce the heat loss of the window by almost half. For example, for ten windows measuring 1.0 mx 1.6 m, the savings will reach a kilowatt, which gives 720 kWh per month.
For the correct choice of materials and thickness of enclosing structures, we apply this information to a specific example.
In calculating the heat loss per one square meter. meter involves two quantities:

• temperature difference ΔT,
• resistance to heat transfer R.

The temperature in the room is determined at 20 ° C, and the outside temperature is assumed to be -30 ° C. Then the temperature difference ΔT will be equal to 50 ° C. The walls are made of a bar with a thickness of 20 cm, then R = 0.806 ° С · m. sq. m. / W.
The thermal losses will be 50 / 0,806 = 62 (W / m2).
To simplify the calculation of heat losses in building reference books lead heat loss of different types of walls, ceilings, etc. for some values ​​of the winter air temperature. In particular, different figures are given for corner rooms (there is a twist of the air flowing around the house) and non-corner rooms, and also takes into account the different thermal picture for the premises of the first and the upper floor.

1.5 Table - Specific heat losses of building fencing elements

(per 1 sq. m. along the inner contour of the walls), depending on the average temperature of the coldest week of the year.

1.6 Table - Specific heat losses of building fencing elements

(per 1 sq. m. by internal contour), depending on the average temperature of the coldest week of the year.

2. Let us consider an example of calculation

heat losses of two different rooms of the same area using tables. Example 1.

2.1 Corner Room (Ground Floor)

Room Characteristics:

• floor first,
• the area of ​​the room is 16 square meters. m. (5x3.2),
• height of the ceiling - 2,75 m,
• outer walls - two,
• material and thickness of the external walls - a bar 18 cm thick, sheathed with plasterboard and wallpapered,
• windows - two (height 1.6 m, width 1.0 m) with double glazing,
• floors - wooden insulated, from below the basement,
• above the attic floor,
• the calculated outdoor temperature is -30 ° C,
• the required room temperature is +20 ° C.

Calculate the area of ​​heat-dissipating surfaces.

The area of ​​the exterior walls minus the windows:

S walls (5 + 3,2) х2,7-2х1,0х1,6 = 18,94 square meters. m.

Area of ​​windows:

S windows = 2x1.0x1.6 = 3.2 square meters. m.

Floor area:

S floor = 5x3.2 = 16 square meters. m.

Ceiling area:

S ceiling = 5x3.2 = 16 square meters. m.

The area of ​​internal partitions is not involved in the calculation, because through them the heat does not go away - after all, on both sides of the partition the temperature is the same. The same applies to the inner door.
Now calculate the heat loss of each of the surfaces:

Q total = 3094 watts.

It should be noted that through the walls more heat passes through windows, floors and ceilings.
The result of the calculation shows the heat loss of the room in the most frosty (T = 30 ° C) days of the year. Naturally, the warmer on the street, the less will leave the room heat.

2.2 Room under the roof (attic)

Room Characteristics:

• floor upper,
• an area of ​​16 square meters. m. (3.8 x 4.2),
• ceiling height 2.4 m,
• exterior walls; two slopes of the roof (slate, continuous crate, 10 cm min wool, lining), gables (10 cm thick panel lined with lining) and side partitions (skeleton with 10 cm claydite filling),
• windows - four (two on each pediment), a height of 1.6 m and a width of 1.0 m with double glazing,
• the calculated outdoor temperature is -30 ° C,
• the required room temperature is + 20 ° C.

2.3 Calculate the areas of heat-dissipating surfaces.

The area of ​​the end walls outside the windows:

S end. walls = 2х (2,4х3,8-0,9х0,6 - 2х1,6х0,8) = 12 square meters. m.

The area of ​​the roof slopes bounding the room:

S skates. walls = 2х1,0х4,2 = 8,4 square meters. m.

Area of ​​side partitions:

S side. peregor = 2х1,5х4,2 = 12,6 кв. m.

Area of ​​windows:

S windows = 4x1.6x1.0 = 6.4 square meters. m.

Ceiling area:

S ceiling = 2,6x4,4 = 10,92 square meters. m.

2.4 Now calculate the heat loss of these surfaces, while we take into account that the floor does not leave heat (there is a warm room). Heat loss for walls and ceiling we consider as for corner spaces, and for the ceiling and side partitions we introduce a 70% coefficient, since behind them there are unheated rooms.

The total heat loss of the room is:

Q total = 4504 W.

As you can see, a warm room on the ground floor loses (or consumes) much less heat than a mansard room with thin walls and a large glazing area.
To make such a room suitable for winter residence, it is necessary first of all to insulate walls, side partitions and windows.
Any enclosing structure can be presented in the form of a multi-layered wall, each layer of which has its own thermal resistance and its resistance to the passage of air. Adding the thermal resistance of all layers, we get the thermal resistance of the entire wall. Also summarizing the resistance to the passage of air of all layers, we will understand how the wall breathes. The ideal wall from a bar should be equivalent to a wall from a bar in the thickness of 15 - 20 cm. The table below will help in this.

2.5 Table   - Resistance to heat transfer and air passage

of various materials ΔT = 40 ° C (T = 20 ° C, T internal = 20 ° C.)

1. The loss of heat through the contact of the foundation with the frozen soil usually takes 15% of the heat loss through the walls of the first floor (given the complexity of the calculation).
2. Loss of heat associated with ventilation. These losses are calculated taking into account construction norms (SNiP). For a residential house, about one air exchange per hour is required, that is, during this time it is necessary to submit the same amount of fresh air. Thus, the losses associated with ventilation are a little less than the amount of heat lost to the enclosing structures. It turns out that the heat loss through the walls and the glazing is only 40%, and the heat loss for ventilation is 50%. In the European norms of ventilation and wall insulation, the ratio of heat losses is 30% and 60%.
3. If the wall "breathes", like a wall made of a log or a log with a thickness of 15 - 20 cm, then a heat return occurs. This makes it possible to reduce the heat loss by 30%, so the value of the thermal resistance of the wall obtained in the calculation should be multiplied by 1.3 (or, respectively, the heat loss).

3. Conclusions:

Summing up all the heat losses at home, you will determine what capacity the heat generator (boiler) and heating appliances are needed for comfortable heating of the house on the coldest and windiest days. Also, calculations of this kind will show where the "weak link" and how to exclude it with the help of additional isolation.
Calculate the heat consumption can be and on the enlarged indicators. So, in one- and two-story not very insulated houses with an outside temperature of -25 ° C, 213 watts per square meter of total area are required, and at 230 ° -30 ° C it is 230 W. For well-insulated houses - this: at -25 ° C - 173 watts per square. m total area, and at -30 ° C - 177 W. Conclusions and recommendations

1. The cost of thermal insulation relative to the cost of the entire house is very small, but when operating a building, the main costs are for heating. On thermal insulation in any case can not be saved, especially when comfortable living in large areas. Energy prices around the world are constantly rising.
2. Modern building materials have a higher thermal resistance than traditional materials. This allows you to make the walls thinner, and therefore cheaper and easier. All this is good, but thin walls have less heat capacity, that is, they store heat worse. To heat it is necessary to constantly - walls quickly heat up and quickly cool down. In old houses with thick walls on a hot summer day, the cool, cool walls of the night "accumulated cold".
3. Warming should be considered together with the air permeability of the walls. If the increase in thermal resistance of walls is associated with a significant decrease in air permeability, then it should not be used. The ideal wall for air permeability is equivalent to a wall made of a bar with a thickness of 15 ... 20 cm.
4. Very often, improper application of vapor barrier leads to a deterioration in the sanitary and hygienic properties of housing. With properly organized ventilation and "breathing" walls, it is unnecessary, and with poorly air-permeable walls, this is unnecessary. Its main purpose is to prevent the infiltration of walls and protect the insulation from the wind.
5. Warming of walls outside is much more effective than internal insulation.
6. Do not endlessly insulate walls. The effectiveness of this approach to energy conservation is not high.
7. Ventilation - these are the main reserves of energy conservation.
8. Using modern glazing systems (double-glazed windows, heat-shielding glass, etc.), low-temperature heating systems, effective thermal insulation of the enclosing structures, you can reduce the cost of heating by 3 times.

The climate in most of our country is very harsh. Therefore, almost any house built outside the city needs to be insulated. A variety of materials can be used to carry out this procedure. When selecting an insulator, first of all, attention is paid to the degree of its thermal conductivity. The lower it is, the more efficient the skin will be. To determine this indicator, there is a special table of thermal conductivity of building materials.

Insulators foamed

This group of materials in terms of heat conservation is considered the best. To her in the first place are such insulators, as polystyrene foam and polystyrene. Table thermal conductivity of building materials SNiP their effectiveness demonstrates clearly.

They take to the advantages of insulators of this group and the fact that they are absolutely not afraid of moisture. The main disadvantage of all foamed materials is that they are completely unable to pass through moisture vapor. The so-called thermos effect appears in the houses they have finished. And consequently, the owners have to take additional measures to improve the microclimate in the premises - to install air conditioners and a ventilation system. Also the disadvantage of these materials is that they practically do not delay extraneous noise. In addition, foamed insulators are very fond of gnawing mice and rats, doing their moves in them. And it, certainly, promotes infringement of tightness of a warming layer and decrease in its efficiency.

Mineral wool

This is the second most popular type of insulator. Heat in the rooms, it retains slightly worse foamed materials. To this group are mainly basalt and glass wool. The main advantages of this type of insulation are low cost, as well as good vapor and sound insulation properties. The disadvantages of mineral wool are its ability to absorb moisture. Also the disadvantage of these materials is that they release harmful phenol-formaldehyde resin vapors.

What to consider when choosing

When buying an insulator, first of all, pay attention to such a parameter as its thickness. Also for the effective insulation is very important indicator such as the thermal conductivity of building materials. A table with the values ​​inherent in different types of insulators will be presented below.

The required material thickness depends on several factors:

the degree of its thermal conductivity;

climatic zone;

the degree of thermal conductivity of the material of the enclosing structures;

For houses in the middle band of Russia, according to the standards, it is necessary to arrange a warming layer of such thickness that its ability to keep the heat is the same as for a brickwork of 1.5 meters.

For wooden buildings, this figure may be smaller. The fact is that the log and log itself are very good at keeping the heat.

Table of thermal conductivity of building materials

So, what are the properties of this or that insulator in this respect? How well modern building materials of this variety retain heat, you can learn from the table.

The table of thermal conductivity of building materials, thus, shows that the most effective insulation at the moment is expanded polystyrene. Vata, as already mentioned, is able to hold the cold a little worse.

Which material to choose

Thus, the heat conductivity of building materials is a very important indicator of the effectiveness of insulation of building enclosures. The table, of course, is not the only way to know its coefficient. The degree of thermal conductivity of the insulator is usually indicated on it by the manufacturer. At the same time, the following values ​​can be entered on the label:

the degree of thermal conductivity in a dry room at a temperature of 10 ° C;

in a dry room at 25 о С;

in different humidity conditions (A or B).

Both foam materials and cotton wool are usually produced in thicknesses of 10 or 5 cm. As the comparative table of the thermal conductivity of building materials shows, for the middle zone of Russia the thermal insulation layer of stone buildings should not be less than 12-13 cm. However, in practice, 10 cm is usually enough. Therefore, the insulation of out-of-town buildings is performed either in one layer of material of 10 cm, or in two insulators of 5 cm thick. The latter method is used more often. With this technology, the second layer is laid in such a way that the seams of the first are completely blocked. As a result, maximum sealing of the thermal insulation is achieved.

The materials intended for the isolation of country houses, in our time, as you can see, there are many. If desired, for insulation, you can choose both foamed version, and mineral wool. The effect, as the table of thermal conductivity of building materials shows, will be both remarkable in both cases. However, of course, only when the sheathing of the enclosing structures will be of sufficient thickness.