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Heat losses of various types of houses. Calculation of heat loss at home: online calculator. Now let's see the thermal resistance of the materials used

So that your house does not turn out to be a bottomless pit for heating costs, we suggest studying the basic directions of thermal engineering research and calculation methodology.

So that your house does not turn out to be a bottomless pit for heating costs, we suggest studying the basic directions of thermal engineering research and calculation methodology.

Without preliminary calculation thermal permeability and moisture accumulation, the whole essence of housing construction is lost.

Physics of thermal processes

Different areas of physics have much in common in describing the phenomena they study. So it is in heat engineering: the principles describing thermodynamic systems clearly echo the foundations of electromagnetism, hydrodynamics and classical mechanics. After all, we are talking about the description of the same world, so it is not surprising that models of physical processes are characterized by some common features in many areas of research.

The essence of thermal phenomena is easy to understand. The temperature of a body or the degree of its heating is nothing but a measure of the intensity of oscillations of the elementary particles of which this body is composed. Obviously, when two particles collide, the one with the higher energy level will transfer energy to the particle with lower energy, but never vice versa.

However, this is not the only way of energy exchange; transfer is also possible through thermal radiation quanta. At the same time, the basic principle is necessarily preserved: a quantum emitted by a less heated atom is not able to transfer energy to a hotter one. elementary particle. It is simply reflected from it and either disappears without a trace, or transfers its energy to another atom with less energy.

Thermodynamics is good because the processes occurring in it are absolutely visual and can be interpreted under the guise of various models. The main thing is to observe the basic postulates, such as the law of energy transfer and thermodynamic equilibrium. So if your presentation complies with these rules, you will easily understand the method of thermal engineering calculations from and to.

The concept of resistance to heat transfer

The ability of a material to transfer heat is called thermal conductivity. In the general case, it is always higher, the greater the density of the substance and the better its structure is adapted to transmit kinetic vibrations.

The quantity inversely proportional to thermal conductivity is thermal resistance. For each material, this property takes on unique values ​​depending on the structure, shape, and a number of other factors. For example, the efficiency of heat transfer in the thickness of materials and in the zone of their contact with other media may differ, especially if there is at least a minimal layer of matter between the materials in a different state of aggregation. Quantitatively, thermal resistance is expressed as the temperature difference divided by the heat flow rate:

Rt = (T2 - T1) / P

Where:

• Rt - thermal resistance of the section, K / W;
• T2 - temperature of the beginning of the section, K;
• T1 - temperature of the end of the section, K;
• P - heat flux, W.

In the context of calculating heat losses, thermal resistance plays a decisive role. Any enclosing structure can be represented as a plane-parallel barrier to the heat flow. Its total thermal resistance is the sum of the resistances of each layer, while all the partitions are folded into a spatial structure, which is, in fact, a building.

Rt = l / (λ S)

Where:

• Rt - thermal resistance of the circuit section, K / W;
• l - length of the section of the thermal chain, m;
• λ - coefficient of thermal conductivity of the material, W/(m K);
• S - cross-sectional area of ​​the site, m2.

Factors affecting heat loss

Thermal processes correlate well with electrical processes: the temperature difference acts as a voltage, the heat flux can be considered as a current strength, but you don’t even need to come up with your own term for resistance. The concept of least resistance, which appears in heat engineering as cold bridges, is also fully true.

If we consider an arbitrary material in a section, it is quite easy to establish the path of the heat flow both at the micro- and at the macro level. Let us take as the first model concrete wall, in which, due to technological necessity, through fastenings are made with steel rods of arbitrary section. Steel conducts heat somewhat better than concrete, so we can distinguish three main heat fluxes:

• through the concrete
• through steel bars
• from steel bars to concrete

The last heat flow model is the most interesting. Since the steel rod warms up faster, the temperature difference between the two materials will be observed closer to the outer part of the wall. Thus, steel not only "pumps" heat outward by itself, it also increases the thermal conductivity of adjacent masses of concrete.

In porous media, thermal processes proceed in a similar way. Almost all building materials consist of a branched web of solid matter, the space between which is filled with air.

Thus, a solid, dense material serves as the main conductor of heat, but due to the complex structure, the path along which heat spreads turns out to be larger than the cross section. Thus, the second factor that determines thermal resistance is the heterogeneity of each layer and the building envelope as a whole.

The third factor affecting the thermal conductivity, we can name the accumulation of moisture in the pores. Water has a thermal resistance 20–25 times lower than that of air, so if it fills the pores, the overall thermal conductivity of the material becomes even higher than if there were no pores at all. When water freezes, the situation becomes even worse: thermal conductivity can increase up to 80 times. The source of moisture, as a rule, is room air and atmospheric precipitation. Accordingly, the three main methods of combating this phenomenon are external waterproofing of walls, the use of vapor protection and the calculation of moisture accumulation, which must be carried out in parallel with predicting heat loss.

Differentiated calculation schemes

The simplest way to determine the size of the heat loss of a building is to sum up the values ​​of the heat flow through the structures that form this building. This technique fully takes into account the difference in the structure various materials, as well as the specifics of the heat flow through them and at the junctions of one plane to another. Such a dichotomous approach greatly simplifies the task, because different enclosing structures can differ significantly in the design of thermal protection systems. Accordingly, in a separate study, it is easier to determine the amount of heat loss, because various calculation methods are provided for this:

• For walls, heat leakage is quantitatively equal to the total area multiplied by the ratio of the temperature difference to the thermal resistance. In this case, the orientation of the walls to the cardinal points is necessarily taken into account to take into account their heating in daytime, as well as the permeability building structures.
• For floors, the methodology is the same, but the presence of an attic space and its mode of operation are taken into account. Also for room temperature a value of 3–5 °С is taken higher, the calculated humidity is also increased by 5–10%.
• Heat losses through the floor are calculated zonal, describing the belts along the perimeter of the building. This is due to the fact that the temperature of the soil under the floor is higher near the center of the building compared to the foundation part.
• The heat flux through the glazing is determined by the nameplate data of the windows; the type of adjoining windows to the walls and the depth of the slopes must also be taken into account.

Q = S (∆T / Rt)

Where:

• Q- heat loss, W;
• S - wall area, m2;
• ΔT - temperature difference inside and outside the room, ° С;
• Rt - resistance to heat transfer, m2 °C / W.

Calculation example

Before moving on to the demo, let's answer the last question: how to correctly calculate the integral thermal resistance of complex multilayer structures? This, of course, can be done manually, since not many types of load-bearing bases and insulation systems are used in modern construction. However, take into account the presence decorative finishes, interior and facade plaster, as well as the influence of all transients and other factors is quite difficult, it is better to use automated calculations. One of the best online resources for such tasks is smartcalc.ru, which additionally plots the dew point offset depending on climatic conditions.

For example, let's take an arbitrary building, having studied the description of which the reader will be able to judge the set of initial data necessary for the calculation. Available cottage correct rectangular shape with dimensions of 8.5x10 m and a ceiling height of 3.1 m, located in the Leningrad region.

The house has an uninsulated floor on the ground with boards on logs with an air gap, the floor height is 0.15 m higher than the ground planning mark on the site. The wall material is a slag monolith 42 cm thick with internal cement-lime plaster up to 30 mm thick and external slag-cement plaster of the "fur coat" type up to 50 mm thick. The total area of ​​glazing is 9.5 m2; the windows used are double-glazed windows in a heat-saving profile with an average thermal resistance of 0.32 m2 °C/W.

The ceiling is made on wooden beams: it is plastered on shingles from below, filled with blast-furnace slag and covered with clay screed from above, above the ceiling there is a cold-type attic. The task of calculating heat loss is the formation of a thermal protection system for walls.

Floor

First of all, heat losses through the floor are determined. Since their share in the total heat outflow is the smallest, and also due to a large number variables (density and type of soil, freezing depth, massiveness of the foundation, etc.), the calculation of heat losses is carried out according to a simplified method using the reduced resistance to heat transfer. Along the perimeter of the building, starting from the line of contact with the ground, four zones are described - encircling strips 2 meters wide.

For each of the zones, its own value of the reduced resistance to heat transfer is taken. In our case, there are three zones with an area of ​​74, 26 and 1 m2. Let it not bother you total amount areas of zones, which more area building on 16 m2, the reason for this is the double recalculation of the intersecting strips of the first zone in the corners, where heat losses are much higher compared to sections along the walls. Using heat transfer resistance values ​​of 2.1, 4.3, and 8.6 m2 °C/W for zones one through three, we determine the heat flow through each zone: 1.23, 0.21, and 0.05 kW, respectively. .

Walls

Using the terrain data, as well as the materials and thickness of the layers that form the walls, you need to fill in the appropriate fields on the smartcalc.ru service mentioned above. According to the calculation results, the heat transfer resistance is equal to 1.13 m2 °C / W, and the heat flux through the wall is 18.48 W per square meter. With a total wall area (excluding glazing) of 105.2 m2, the total heat loss through the walls is 1.95 kWh. In this case, heat loss through the windows will be 1.05 kW.

Covering and roofing

Calculation of heat loss through attic floor can also be performed in the online calculator by selecting the desired type of enclosing structures. As a result, the resistance of the floor to heat transfer is 0.66 m2 °C/W, and the heat loss is 31.6 W per square meter, that is, 2.7 kW from the entire area of ​​the building envelope.

The total total heat loss according to the calculations is 7.2 kWh. Given the rather low quality of the building structures, this figure is obviously much lower than the real one. In fact, such a calculation is idealized, it does not take into account special coefficients, blowing, the convection component of heat transfer, losses through ventilation and entrance doors.

In fact, due to poor-quality installation of windows, lack of protection at the junction of the roof to the Mauerlat and poor waterproofing of the walls from the foundation real heat loss can be 2 or even 3 times more than the calculated ones. Nevertheless, even basic thermal engineering studies help to determine whether the structures of the house under construction will comply with sanitary standards, at least in the first approximation.

Finally, let's give one important recommendation: If you really want to get a complete understanding of the thermal physics of a particular building, you must use an understanding of the principles described in this overview and specialized literature. For example, a reference manual by Elena Malyavina “Heat loss of a building” can be a very good help in this matter, where the specifics of heat engineering processes are explained in great detail, links are given to the necessary regulations, as well as examples of calculations and all the necessary background information.published

If you have any questions on this topic, ask them to specialists and readers of our project.

Conventionally, the heat loss of a private house can be divided into two groups:

• Natural - heat loss through the walls, windows or roof of the building. These are losses that cannot be completely eliminated, but they can be minimized.
• “Heat leaks” are additional heat losses that can most often be avoided. These are various visually imperceptible errors: hidden defects, installation errors, etc., which cannot be visually detected. For this, a thermal imager is used.

Below we bring to your attention 15 examples of such “leaks”. These are real problems that are most often found in private homes. You will see what problems may be present in your home and what you should pay attention to.

Poor wall insulation

The isolation doesn't work as well as it could. The thermogram shows that the temperature on the wall surface is unevenly distributed. That is, some sections of the wall heat up more than others (than brighter color, the higher the temperature). And this means that the heat loss is not stronger, which is wrong for an insulated wall.

IN this case bright areas are an example of inefficient insulation performance. It is likely that the foam in these places is damaged, poorly installed or missing altogether. Therefore, after the building is insulated, it is important to make sure that the work is done efficiently and that the insulation works effectively.

Poor roof insulation

joint between wooden beam And mineral wool insufficiently compacted. Because of this, the insulation does not work effectively and provides additional heat loss through the roof that could have been avoided.

The radiator is clogged and gives off little heat

One of the reasons why it is cold in the house is that some sections of the radiator do not heat up. This can be caused by several reasons: construction debris, air accumulation or factory defects. But the result is the same - the radiator works at half its heating capacity and does not heat the room enough.

The radiator "heats" the street

Another example of an inefficient radiator.

A radiator is installed inside the room, which heats the wall very strongly. As a result, part of the heat emitted by it goes outside. In fact, the heat is used to heat the street.

Close laying of underfloor heating to the wall

The underfloor heating pipe is laid close to the outer wall. The coolant in the system is cooled more intensively and it has to be heated more often. The result is an increase in heating costs.

The influx of cold through the cracks in the windows

Often there are gaps in the windows that appear due to:

• insufficient pressing of the window to the window frame;
• wear of sealing rubber bands;
• Poor window installation.

Through the cracks, cold air constantly enters the room, due to which drafts are unhealthy and increase the heat loss of the building.

The influx of cold through the cracks in the doors

Also, cracks appear in the balcony and entrance doors.

Bridges of cold

"Cold bridges" are areas of the building with lower thermal resistance in relation to other areas. That is, they let in more heat. For example, these are corners, concrete lintels above windows, junctions of building structures, and so on.

Why cold bridges are harmful:

• Increase the heat loss of the building. Some bridges lose more heat, others less. It all depends on the characteristics of the building.
• At certain conditions condensation forms in them and a fungus appears. Such potentially dangerous areas need to be warned and eliminated in advance.

Cooling the room through ventilation

Ventilation works in reverse. Instead of removing air from the room to the outside, cold street air is drawn into the room from the street. This also, as in the example with windows, provides drafts and cools the room. In the above example, the temperature of the air that enters the room is -2.5 degrees, at a room temperature of ~ 20-22 degrees.

The influx of cold through the sunroof

And in this case, the cold enters the room through the hatch to the attic.

The influx of cold through the mounting hole of the air conditioner

The influx of cold into the room through the mounting hole of the air conditioner.

Heat loss through walls

The thermogram shows "heat bridges" associated with the use of materials with weaker resistance to heat transfer during the construction of the wall.

Heat loss through foundation

Often, when insulating the wall of a building, they forget about another important area - the foundation. Heat losses are also carried out through the foundation of the building, especially if the building has a basement or a warm floor is laid inside.

Cold wall due to masonry joints

Masonry joints between bricks are numerous cold bridges and increase heat loss through the walls. The example below shows that the difference between minimum temperature(masonry joint) and maximum (brick) is almost 2 degrees. The thermal resistance of the wall is reduced.

air leaks

Bridge of cold and air leak under the ceiling. It occurs due to insufficient sealing and insulation of the joints between the roof, wall and floor slab. As a result, the room is additionally cooled and drafts appear.

Conclusion

All this typical mistakes, which are found in most private homes. Many of them are easily eliminated and can significantly improve the energy state of the building.

Let's list them again:

1. Heat leakage through walls;
2. Inefficient work of thermal insulation of walls and roof - hidden defects, poor-quality installation, damage, etc.;
3. Cold inflows through the mounting holes of the air conditioner, cracks in windows and doors, ventilation;
4. Inefficient operation of radiators;
5. Bridges of cold;
6. Influence of masonry joints.

15 hidden heat leaks in a private house that you did not know about

The calculation of the heating of a private house can be done independently by taking some measurements and substituting your values ​​into the necessary formulas. Let's tell you how it's done.

We calculate the heat loss of the house

Several critical parameters of the heating system and, first of all, the power of the boiler depend on the calculation of the heat loss of the house.

The calculation sequence is as follows:

We calculate and write down in a column the area of ​​​​windows, doors, external walls, floors, ceilings of each room. Opposite each value we write down the coefficient from which our house is built.

If you didn't find desired material in, then look in the extended version of the table, which is called so - the coefficients of thermal conductivity of materials (soon on our website). Further, according to the formula below, we calculate the heat loss of each structural element of our house.

Where Q– heat loss, W
S— construction area, m2
Δ T— temperature difference between indoors and outdoors for the coldest days °C

R— the value of thermal resistance of the structure, m2 °C/W

Where V— layer thickness in m,

λ - coefficient of thermal conductivity (see table for materials).

We summarize the thermal resistance of all layers. Those. for walls, both plaster and wall material and external insulation (if any) are taken into account.

Putting it all together Q for windows, doors, exterior walls, floors, ceilings

We add 10-40% of ventilation losses to the amount received. They can also be calculated by the formula, but with good windows and moderate ventilation, you can safely set 10%.

We divide the result by total area Houses. It is the general, because heat will indirectly be spent on corridors where there are no radiators. The calculated value of specific heat loss can vary within 50-150 W/m2. The highest heat losses are in the rooms of the upper floors, the lowest in the middle ones.

After graduation installation work, conduct walls, ceilings and other structural elements to make sure that there are no heat leaks anywhere.

The table below will help you more accurately determine the indicators of materials.

Determining the temperature

This stage is directly related to the choice of the boiler and the method of space heating. If it is planned to install "warm floors", it is possible The best decision– condensing boiler and low temperature regime 55C in the supply and 45C in the "return". This mode ensures the maximum efficiency of the boiler and, accordingly, the best gas savings. In the future, if you want to use high-tech heating methods, ( , solar collectors) you do not have to remake the heating system for new equipment, because It is designed specifically for low temperatures. Additional pluses - the air in the room does not dry out, the flow rate is lower, less dust is collected.

In the case of choosing a traditional boiler, it is better to choose the temperature regime as close as possible to European standards 75C - at the outlet of the boiler, 65C - return flow, 20C - room temperature. This mode is provided in the settings of almost all imported boilers. In addition to choosing a boiler, the temperature regime affects the calculation of the power of radiators.

Selection of power radiators

For the calculation of heating radiators for a private house, the material of the product does not play a role. This is a matter of taste of the owner of the house. Only the power of the radiator indicated in the product passport is important. Often manufacturers indicate inflated figures, so the result of the calculations will be rounded up. The calculation is made for each room separately. Simplifying somewhat the calculations for a room with ceilings of 2.7 m, we give a simple formula:

Where TO- desired number of radiator sections

S- area of ​​the room

P- power indicated in the product passport

Calculation example: For a room with an area of ​​30 m2 and a power of one section of 180 W, we get: K = 30 x 100/180

K=16.67 rounded 17 sections

The same calculation can be applied to cast iron batteries, assuming that

1 rib(60 cm) = 1 section.

Hydraulic calculation of the heating system

The meaning of this calculation is to choose the right pipe diameter and characteristics. Due to the complexity of the calculation formulas, it is easier for a private house to select pipe parameters from the table.

Here is the total power of the radiators for which the pipe supplies heat.

We calculate the volume of the heating system

This value is necessary to select the correct volume expansion tank. It is calculated as the sum of the volumes in the radiators, pipelines and boiler. reference Information for radiators and pipelines is given below, for the boiler - indicated in his passport.

The volume of coolant in the radiator:

• aluminum section - 0.450 liters
• bimetallic section - 0.250 liters
• new cast iron section- 1,000 liters
• old cast iron section - 1,700 liters

The volume of the coolant in 1 l.m. pipes:

• ø15 (G ½") - 0.177 liters
• ø20 (G ¾") - 0.310 liters
• ø25 (G 1.0″) - 0.490 liters
• ø32 (G 1¼") - 0.800 liters
• ø15 (G 1½") - 1.250 liters
• ø15 (G 2.0″) - 1.960 liters

Installation of the heating system of a private house - the choice of pipes

It is carried out with pipes from different materials:

Steel

• They have a lot of weight.
• They require proper skill, special tools and equipment for installation.
• Corrosion resistant
• May accumulate static electricity.

Copper

• Withstand temperatures up to 2000 C, pressure up to 200 atm. (in a private house, completely unnecessary dignity)
• Reliable and durable
• Have a high cost
• Mounted with special equipment, silver solder

Plastic

• Antistatic
• Corrosion resistant
• Inexpensive
• Have minimal hydraulic resistance
• Requires no special skills for installation

Summarize

Correctly made calculation of the heating system of a private house provides:

• Comfortable warmth in the rooms.
• Sufficient amount of hot water.
• Silence in the pipes (no gurgling or growling).
• Optimal boiler operating modes
• Correct load on the circulation pump.
• Minimum installation costs

Comfort is a tricky thing. Sub-zero temperatures come, it immediately becomes chilly, and uncontrollably drawn to home improvement. "Global warming" begins. And there is one “but” here - even after calculating the heat loss of the house and installing the heating “according to the plan”, you can stay face to face with the quickly leaving heat. The process is not visually noticeable, but it feels great through woolen socks and big heating bills. The question remains - where did the "precious" heat go?

Natural heat losses are well hidden behind load-bearing structures or “well-made” insulation, where there should not be gaps by default. But is it? Let's look at the issue of thermal leakage for different structural elements.

Cold places on the walls

Up to 30% of all heat loss at home falls on the walls. In modern construction, they are multilayer structures made of materials with different thermal conductivity. Calculations for each wall can be carried out individually, but there are errors common to all, through which heat leaves the room, and cold enters the house from the outside.

The place where the insulating properties are weakened is called the “cold bridge”. For walls it is:

• Masonry joints

The optimal masonry seam is 3mm. It is achieved more often with adhesive compositions of fine texture. When the volume of the solution between the blocks increases, the thermal conductivity of the entire wall increases. Moreover, the temperature of the masonry seam can be 2-4 degrees colder than the base material (brick, block, etc.).

Masonry joints as a "thermal bridge"

• Concrete lintels over openings.

One of the highest thermal conductivity coefficients among building materials(1.28 - 1.61 W / (m * K)) for reinforced concrete. This makes it a source of heat loss. The issue is not completely resolved by cellular or foam concrete lintels. The temperature difference between the reinforced concrete beam and the main wall is often close to 10 degrees.

It is possible to isolate the jumper from the cold with continuous external insulation. And inside the house - by assembling a box from the Civil Code under the eaves. This creates an additional air gap for heat.

• Mounting holes and fasteners.

Connecting an air conditioner, TV antenna leaves holes in the overall insulation. Through metal fasteners and the passage hole must be tightly sealed with insulation.

And if possible, do not bring metal fasteners out, fixing them inside the wall.

Insulated walls also have defects with heat loss.

Installation of damaged material (with chips, squeezing, etc.) leaves vulnerable areas for heat leakage. This is clearly seen when examining the house with a thermal imager. Bright spots show gaps in the outer insulation.

During operation, it is important to monitor general condition insulation. An error in the choice of glue (not special for thermal insulation, but tiled) can give out cracks in the structure after 2 years. Yes, and the main insulation materials also have their drawbacks. For example:

• Mineral wool - does not rot, and is not interesting to rodents, but is very sensitive to moisture. Therefore, its good service life in external insulation is about 10 years - then damage appears.
• Styrofoam - has good insulating properties, but is easily amenable to rodents, and is not resistant to force and ultraviolet radiation. The insulation layer after installation requires immediate protection (in the form of a structure or a layer of plaster).

When working with both materials, it is important to observe a clear fit of the locks of the insulation boards and the cross arrangement of the sheets.

• Polyurethane foam - creates seamless insulation, convenient for uneven and curved surfaces, but vulnerable to mechanical damage and breaks down under UV light. It is desirable to cover plaster mixture- fastening frames through a layer of insulation violates the overall insulation.

Experience! Heat loss can increase during operation, because all materials have their own nuances. It is better to periodically assess the condition of the insulation and repair damage immediately. A crack on the surface is a “high-speed” road to the destruction of the insulation inside.

Foundation heat loss

Concrete is the predominant material in foundation construction. Its high thermal conductivity and direct contact with the ground give up to 20% of heat loss around the entire perimeter of the building. The foundation conducts heat especially strongly from the basement and improperly installed underfloor heating on the ground floor.

Heat loss is also increased by excess moisture not removed from the house. It destroys the foundation, creating loopholes for the cold. Humidity sensitive and many thermal insulation materials. For example, mineral wool, which often goes to the foundation from general insulation. It is easily damaged by moisture, and therefore requires a dense protective frame. Expanded clay also loses its thermal insulation properties permanently wet ground. Its structure creates air cushion and well compensates for the pressure of soils during freezing, but the constant presence of moisture minimizes beneficial features expanded clay in insulation. That is why the creation of working drainage - required condition long life of the foundation and heat preservation.

In terms of importance, this also includes the waterproofing protection of the base, as well as a multi-layer blind area, at least a meter wide. At column foundation or heaving soil, the blind area around the perimeter is insulated to protect the soil at the base of the house from freezing. The blind area is insulated with expanded clay, sheets of expanded polystyrene or polystyrene.

Sheet materials for foundation insulation are best chosen with groove connection, and treat it with a special silicone compound. The tightness of the locks blocks access to the cold and guarantees complete protection of the foundation. In this matter, seamless spraying of polyurethane foam has an indisputable advantage. In addition, the material is elastic and does not crack when the soil is heaving.

For all types of foundations, you can use the developed insulation schemes. An exception may be the foundation on piles, due to its design. Here, when processing the grillage, it is important to take into account the heaving of the soil and choose a technology that does not destroy the piles. This is a complex calculation. Practice shows that a house on stilts protects the well-insulated floor of the first floor from the cold.

Attention! If the house has a basement, and it is often flooded, then this must be taken into account with the insulation of the foundation. Since the insulation / insulator in this case will clog moisture in the foundation, and destroy it. Accordingly, the heat will be lost even more. The first thing to do is solve the problem of flooding.

Vulnerabilities of the floor

An uninsulated ceiling gives off a significant part of the heat to the foundation and walls. This is especially noticeable when the underfloor heating is not properly installed - the heating element cools down faster, increasing the cost of heating the room.

In order for the heat from the floor to go into the room, and not out into the street, you need to make sure that the installation goes according to all the rules. The main ones are:

• Protection. A damper tape (or foil polystyrene sheets up to 20 cm wide and 1 cm thick) is attached to the walls around the entire perimeter of the room. Before this, the gaps are necessarily eliminated, and the surface of the wall is leveled. The tape is fixed as tightly as possible to the wall, isolating the heat transfer. When there are no air pockets, there are no heat leaks.
• Indent. From outer wall to the heating circuit should be at least 10 cm. If the warm floor is mounted closer to the wall, then it starts to heat the street.
• Thickness. The characteristics of the necessary screen and insulation for underfloor heating are calculated individually, but it is better to add 10-15% of the margin to the figures obtained.
• Finishing. The screed over the floor should not contain expanded clay (it isolates heat in concrete). Optimal Thickness screeds 3-7 cm. The presence of a plasticizer in a mixture of concrete improves thermal conductivity, and hence heat transfer to the room.

Serious insulation is relevant for any floor, and not necessarily heated. Poor thermal insulation turns the floor into a large "radiator" for the ground. Should it be heated in winter?

Important! Cold floors and dampness appear in the house when ventilation of the underground space is not working or not done (vents are not organized). No heating system compensates for such a shortcoming.

Places of adjoining building structures

Compounds violate the integral properties of materials. Therefore, corners, joints and junctions are so vulnerable to cold and moisture. The junctions of concrete panels are the first to dampen, and fungus and mold appear there. The temperature difference between the corner of the room (the place where structures are joined) and the main wall can vary from 5-6 degrees to sub-zero temperatures and condensation inside the corner.

Clue! At the places of such connections, the masters recommend making an increased layer of insulation from the outside.

Heat often escapes through interfloor overlap when the slab is laid on the entire thickness of the wall and its edges go out into the street. Here, heat losses of both the first and second floors increase. Drafts are formed. Again, if there is a warm floor on the second floor, external insulation should be designed for this.

Heat leakage through ventilation

The heat from the room is removed through equipped ventilation ducts that provide healthy air exchange. Ventilation, working "on the contrary", tightens the cold from the street. This happens when there is a lack of air in the room. For example, when the switched on fan in the hood takes too much air from the room, due to which it begins to be drawn in from the street through other exhaust channels(without filters and heating).

Questions of how not to bring a large amount of heat outside, and how not to let cold air into the house, have long had their own professional solutions:

1. Recuperators are installed in the ventilation system. They return up to 90% of heat to the house.
2. Settling down supply valves. They "prepare" the outdoor air in front of the room - it is cleaned and warmed. The valves come with manual adjustment or automatic, which focuses on the difference in temperature outside and inside the room.

Comfort is worth good ventilation. With normal air exchange, mold does not form, and a healthy microclimate is created for living. That is why a well-insulated house with a combination of insulating materials must necessarily have working ventilation.

Outcome! To reduce heat loss through ventilation ducts it is necessary to eliminate errors in the redistribution of air in the room. In well-functioning ventilation, only warm air leaves the house, some of the heat from which can be returned back.

Heat loss through windows and doors

Through door and window openings, the house loses up to 25% of heat. Weak spots for doors, this is a leaky seal that can be easily re-glued to a new one and a thermal insulation that has strayed inside. It can be replaced by removing the cover.

Vulnerabilities for wood and plastic doors similar to "cold bridges" in similar window designs. Therefore, we will consider the general process using their example.

What gives out "window" heat loss:

• Explicit gaps and drafts (in the frame, around the window sill, at the junction of the slope and the window). Poor sash fit.
• Damp and moldy internal slopes. If the foam and plaster have lagged behind the wall over time, then the moisture from the outside gets closer to the window.
• Cold glass surface. For comparison - energy-saving glass (at -25 ° outside, and inside the room + 20 °) has a temperature of 10-14 degrees. And, of course, it does not freeze.

The sashes may not fit snugly when the window is not adjusted and the rubber bands around the perimeter have worn out. The position of the flaps can be adjusted independently, as well as change the seal. It is better to replace it completely every 2-3 years, and preferably with a “native” production seal. Seasonal cleaning and lubrication of rubber bands maintains their elasticity during temperature changes. Then the sealant does not let the cold through for a long time.

Slots in the frame itself (relevant for wooden windows) are filled with silicone sealant, preferably transparent. When it hits the glass, it's not so noticeable.

The joints of the slopes and the window profile are also sealed with sealant or liquid plastic. In a difficult situation, you can use self-adhesive polyethylene foam - "insulating" adhesive tape for windows.

Important! It is worth making sure that in the decoration of the external slopes, the insulation (polystyrene, etc.) completely covers the seam polyurethane foam and the distance to the middle of the window frame.

Modern ways to reduce heat loss through glass:

• Use of PVI films. They reflect wave radiation and reduce heat loss by 35-40%. Films can be glued to an already installed double-glazed window if there is no desire to change it. It is important not to confuse the sides of the glass and the polarity of the film.
• Installation of glass with low emission characteristics: k- and i-glass. Double-glazed windows with k-glasses transmit the energy of short waves of light radiation into the room, accumulating the body in it. Long-wave radiation no longer leaves the room. As a result, the glass on the inner surface has a temperature twice as high as that of conventional glass. i-glass holds thermal energy in the house by reflecting up to 90% of the heat back into the room.
• The use of silver-coated glasses, which are 2x chamber double-glazed windows save 40% more heat (compared to conventional glasses).
• The choice of double-glazed windows with an increased number of glasses and the distance between them.

Healthy! Reduce heat loss through glass - organized air curtains above the windows (can be in the form warm skirting boards) or protective shutters for the night. Especially relevant when panoramic glazing and extreme sub-zero temperatures.

Causes of heat leakage in the heating system

Heat loss also applies to heating, where heat leakage occurs more often for two reasons.

• A powerful radiator without a protective screen heats the street.

• Not all radiators fully warm up.

Compliance with simple rules reduces heat loss and prevents the heating system from working “idle”:

1. A reflective screen should be installed behind each radiator.
2. Before starting the heating, once a season, it is necessary to bleed the air from the system and see if all the radiators are fully warmed up. The heating system can become clogged due to accumulated air or debris (delaminations, poor quality water). Once every 2-3 years, the system must be completely flushed.

The note! When refilling, it is better to add anti-corrosion inhibitors to the water. This will support the metal elements of the system.

Heat loss through the roof

Heat initially tends to the top of the house, which makes the roof one of the most vulnerable elements. It accounts for up to 25% of all heat losses.

Cold attic space or a residential attic are insulated equally tightly. The main heat losses occur at the junctions of materials, it does not matter whether it is insulation or structural elements. So, the often overlooked bridge of cold is the border of the walls with the transition to the roof. It is desirable to process this area together with the Mauerlat.

The main insulation also has its own nuances, related more to the materials used. For example:

1. Mineral wool insulation should be protected from moisture and it is advisable to change every 10 - 15 years. Over time, it cakes and begins to let heat through.
2. Ecowool, which has excellent properties of "breathing" insulation, should not be near hot springs - when heated, it smolders, leaving gaps in the insulation.
3. When using polyurethane foam, it is necessary to equip ventilation. The material is vapor-tight, and it is better not to accumulate excess moisture under the roof - other materials are damaged, and a gap appears in the insulation.
4. Slabs in multilayer thermal insulation must be laid in a checkerboard pattern and must be closely adjacent to the elements.

Practice! In overhead structures, any gap can remove a lot of expensive heat. Here it is important to focus on dense and continuous insulation.

Conclusion

It is useful to know the places of heat loss not only in order to equip a house and live in comfortable conditions, but also not to overpay for heating. Proper insulation in practice pays off in 5 years. The term is long. But after all, we are not building a house for two years.

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Energy-efficient reconstruction of the building will help to save thermal energy and increase the comfort of life. The greatest savings potential lies in the good thermal insulation of the outer walls and roof. The easiest way to assess opportunities effective repair is the consumption of thermal energy. If more than 100 kWh of electricity (10 m³ natural gas) on square meter heated area, including wall area, then energy-saving renovations can be beneficial.

Heat loss through the outer shell

The basic concept of an energy-saving building is a continuous layer of thermal insulation over the heated surface of the house contour.

1. Roof. With a thick layer of thermal insulation, heat loss through the roof can be reduced;

Important! In wooden structures, the thermal seal of the roof is difficult, as the wood swells and can be damaged by high humidity.

1. Walls. As with a roof, heat loss is reduced by the use of a special coating. When internal thermal insulation walls there is a risk that condensate will collect behind the insulation if the humidity in the room is too high;

1. Floor or basement. For practical reasons, thermal insulation is made from inside the building;
2. thermal bridges. Thermal bridges are unwanted cooling fins (heat conductors) on the outside of a building. For example, a concrete floor, which is also a balcony floor. Many thermal bridges are found in soil areas, parapets, window and door frames. There are also temporary thermal bridges if the wall details are fixed metal elements. Thermal bridges can account for a significant portion of heat loss;
3. Window. Over the past 15 years, the thermal insulation of window glass has improved 3 times. Today's windows have a special reflective layer on the glass, which reduces radiation losses, these are single- and double-glazed windows;
4. Ventilation. A typical building has air leaks, especially around windows, doors and on the roof, which provides the necessary air exchange. However, during the cold season, this causes significant heat loss from the house from the outgoing heated air. Good modern buildings are quite airtight, and it is necessary to regularly ventilate the premises by opening windows for a few minutes. To reduce heat loss through ventilation, comfort panels are increasingly being installed. ventilation systems. This type of heat loss is estimated at 10-40%.

Thermographic surveys in a poorly insulated building give an idea of ​​how much heat is being wasted. This is very good tool for quality control of repair or new construction.

Ways to assess heat loss at home

There are complex calculation methods that take into account various physical processes: convection exchange, radiation, but they are often redundant. Simplified formulas are usually used, and if necessary, 1-5% can be added to the result. The orientation of the building is taken into account in new buildings, but solar radiation also does not significantly affect the calculation of heat losses.

Important! When applying formulas for calculating heat losses, the time spent by people in a particular room is always taken into account. The smaller it is, the lower temperature indicators should be taken as a basis.

1. Average values. The most approximate method does not have sufficient accuracy. There are tables compiled for individual regions, taking into account climatic conditions and average building parameters. For example, for a specific area, the power value in kilowatts is indicated, which is required to heat 10 m² of room area with 3 m high ceilings and one window. If the ceilings are lower or higher, and there are 2 windows in the room, the power indicators are adjusted. This method does not take into account the degree of thermal insulation of the house at all and will not save thermal energy;
2. Calculation of heat loss of the enclosing contour of the building. Summarized area external walls minus the dimensions of the areas of windows and doors. Additionally, there is a roof area with a floor. Further calculations are carried out according to the formula:

Q = S x ΔT/R, where:

• S is the found area;
• ΔT is the difference between indoor and outdoor temperatures;
• R is the resistance to heat transfer.

The result obtained for the walls, floor and roof is combined. Then ventilation losses are added.

Important! Such a calculation of heat losses will help determine the boiler capacity for the building, but will not allow you to calculate the number of radiators per room.

1. Calculation of heat loss by rooms. When using a similar formula, losses are calculated for all rooms of the building separately. Then, heat losses for ventilation are found by determining the volume of air mass and the approximate number of times a day it is changed in the room.

Important! When calculating ventilation losses, it is necessary to take into account the purpose of the room. The kitchen and bathroom need enhanced ventilation.

An example of calculating the heat loss of a residential building

The second calculation method is used, only for the external structures of the house. Through them, up to 90 percent of thermal energy is lost. Accurate results are important in order to select the right boiler to deliver efficient heat without overheating the rooms. It is also an indicator economic efficiency selected materials for thermal protection, showing how quickly you can recoup the cost of their purchase. The calculations are simplified, for a building without a multilayer thermal insulation layer.

The house has an area of ​​10 x 12 m and a height of 6 m. The walls are 2.5 bricks (67 cm) thick, covered with plaster, with a layer of 3 cm. The house has 10 windows 0.9 x 1 m and a door 1 x 2 m.

Calculation of resistance to heat transfer of walls:

1. R = n/λ, where:

• n - wall thickness,
• λ is the specific thermal conductivity (W/(m °C).

This value is looked up in the table for its material.

1. For brick:

Rkir \u003d 0.67 / 0.38 \u003d 1.76 sq.m ° C / W.

1. For plaster coating:

Rpcs \u003d 0.03 / 0.35 \u003d 0.086 sq.m ° C / W;

1. Total value:

Rst \u003d Rkir + Rsht \u003d 1.76 + 0.086 \u003d 1.846 sq.m ° C / W;

Calculation of the area of ​​external walls:

1. Total area of ​​external walls:

S = (10 + 12) x 2 x 6 = 264 sq.m.

1. Area of ​​windows and doorway:

S1 \u003d ((0.9 x 1) x 10) + (1 x 2) \u003d 11 sq.m.

1. Adjusted wall area:

S2 = S - S1 = 264 - 11 = 253 sq.m.

Heat losses for walls will be determined by:

Q \u003d S x ΔT / R \u003d 253 x 40 / 1.846 \u003d 6810.22 W.

Important! The value of ΔT is taken arbitrarily. For each region in the tables, you can find the average value of this value.

At the next stage, heat losses through the foundation, windows, roof, and door are calculated in an identical way. When calculating the heat loss index for the foundation, a smaller temperature difference is taken. Then you need to sum up all the received numbers and get the final one.

To determine the possible consumption of electricity for heating, you can present this figure in kWh and calculate it for the heating season.

If you use only the number for the walls, it turns out:

• per day:

6810.22 x 24 = 163.4 kWh;

• per month:

163.4 x 30 = 4903.4 kWh;

• for the heating season of 7 months:

4903.4 x 7 \u003d 34,323.5 kWh.

When the heating is gas, the gas consumption is determined based on its calorific value and the efficiency of the boiler.

Heat losses for ventilation

1. Find the air volume of the house:

10 x 12 x 6 = 720 m³;

1. The mass of air is found by the formula:

M = ρ x V, where ρ is the air density (taken from the table).

M \u003d 1, 205 x 720 \u003d 867.4 kg.

1. It is necessary to determine the figure, how many times the air in the whole house is replaced per day (for example, 6 times), and calculate the heat loss for ventilation:

Qв \u003d nxΔT xmx С, where С is specific heat for air, n is the number of times the air is replaced.

Qv \u003d 6 x 40 x 867.4 x 1.005 \u003d 209217 kJ;

1. Now we need to convert to kWh. Since there are 3600 kilojoules in one kilowatt-hour, then 209217 kJ = 58.11 kWh

Some calculation methods suggest taking heat losses for ventilation from 10 to 40 percent of the total heat losses, without calculating them using formulas.

To facilitate the calculation of heat loss at home, there are online calculators where you can calculate the result for each room or the entire house. You simply enter your data in the proposed fields.

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