Heat capacity of the building. Comparative analysis of the thermal properties of houses made of different materials

What is the dependence of the temperature in the house on the heat capacity of the walls, which are involved in maintaining the microclimate in the house. The fact is that in most cases we come across thermal insulation materials that only prevent heat loss in the house; they delay heat transfer from the house to the street. But the characteristics of most insulation cannot solve the issue of the heat capacity of the walls, they cannot accumulate infrared heat tending outwards, here two problems need to be solved: to save and accumulate heat. How to solve the issue - interior decoration The DSP board is our thermal energy accumulator. You tell me, I found something to accumulate, let's do the math, add up the walls and floor, calculate the cubic meters of CBF material 10m*12m*2.8m= 2.64m/cube floor, ceiling+4m/cube walls + in the middle of the house there is a middle wall, it can accumulate warmth (Ecowool insulation Vermiculite is better) 12m*2.8m*0.20m=6.7m/cub. A total of 13 m/cube of heat-intensive material dispersed throughout your home. After 1 month, the house gains a cruising heat reserve, which allows you to avoid changes in air temperature when turning off the heat or ventilation. It works great as an ordinary house with classic walls in terms of heat capacity, but it has a number of advantages, firstly, the walls do not cool the air and the temperature difference between the air and the surface does not exceed 2 degrees.

Let's go from the other side, from practice in an industrial building, which is insulated with 5-6 cm of Styrex, the lights were turned off for 2 days. The temperature drops to 5-10 degrees. The wall, floor, and ceiling release the accumulated heat well to the air, and the water does not freeze in any way. A huge plus, after turning on the electricity, the heat is pumped up in 3 hours and reaches 18 in 6-8 hours at 23-25 ​​degrees. This is the experience of operating a frame building, nothing can be added or subtracted. Let's continue to smash myths about disadvantages frame construction. Let's talk about the heat capacity of the building. What I want to clarify, here is an example of a 10*12 house effective area For heating a house of 106 kW/m, 10 kW/hour will be required according to standard heat consumption calculation schemes. This is subject to the insulated perimeter of the building R-2-3. You emit any type of heat 12 kW/hour, in brick houses the insulation that retains heat is located on the outside of the building or in the middle of the wall, so in order to heat the air we will need to first heat all the enclosing structures of the house (walls, floor, ceiling). As soon as the heat completely saturates (heats) all objects, we will begin to warm up the air. To maintain a temperature of 25 degrees. we need to increase the power, either or the periods of operation of the heat emitter. We conclude that heat-intensive structures (walls made of brick, concrete) require more kV\hour. energy to maintain a constant level of heat in the house. Frame houses, as we calculated, have a “13 m³ heat accumulator,” which is approximately 10 times less than brick and foam concrete walls in terms of thermal capacity, but this amount is enough to allow the house to cool down smoothly and for as long as possible in case of force majeure (accident, broken wires, etc.) .d.).

I draw the second conclusion, I do not consider it necessary to overspend thermal energy twice as much to maintain the temperature contour of the walls and the cost of a house made of heat-intensive materials. Relying on the case that “force majeure may happen someday” and we will need heat-intensive walls that will not allow the house to cool down in 1 day, it is stupid to rely on this “fact of heat capacity”, isn’t it, it might be easier to take care of it in advance and buy for 25-30t.rub diesel generator for 5 kW/hour, which has never bothered anyone in a private home. And when “this misfortune” arises, go and turn on Pandora’s box and the life-giving power of heat will flow through your rooms and save the house from global cooling. As practice has shown, the above-described conclusions have proven that frame house consumes 1.5-2 times less heat, this is not a miracle, just compliance with SNIPA R from 3-3.75. You can easily keep a frame house for 5 kW/hour at a temperature of 23-25 ​​degrees in the “maintenance” mode, that is, the thermostat will turn on the voltage to the heaters if the set operating temperature drops. A very interesting application can be drawn from the fact that the house practically does not lose heat; you set the temperature to 15 degrees when you are not at home and two hours before arrival the thermostat reaches 25 degrees - this is a significant saving. I repeat for 5 square meters per hour, even though you can heat an area of ​​91-100 square meters all winter - that’s a fact. For four years I have kept the building three times colder (in terms of thermal resistance) using it as heating infrared heaters. A brick house with an area of ​​91-100 sq.m. will require 10-14 sq.m. per hour and at a constant load. It all works, so drowning the street and the ton structures of the walls of brick houses IS NOT MY WAY, I act as described above, I go start the diesel generator, or you can wait at least a day for the building to cool down to critical temperatures - draw a conclusion.

The information below is available from an Internet resource.

Data:
Heat loss typical homes and other buildings occur for three main reasons:
- due to thermal conductivity through walls, roofs and floors, as well as due to (but to a much lesser extent) radiation and convection;

Due to thermal conductivity and, to a lesser extent, by radiation and convection through windows and other glazing;

By convection and air flow through the elements of the external building envelope, which usually occurs through open windows, doors and ventilation holes(forced or natural) or by infiltration, i.e. air penetration through cracks in the building envelope, for example around the perimeter of door and window frames.

Depending on whether the building has good insulation or not, whether it has many or few windows, whether there is air movement through it or not, each (!) of these three factors makes up 20...50% of the total heat loss of the building.

Let us assume that heat losses in the building occur at equally based on the three factors above. This is graphically illustrated by a diagram in the form of a circle cut into 3 equal parts. If any of these components halve, then the total heat losses will decrease by only 1/6. This suggests that all three factors should be considered equally, without singling out one or the other.

Finding opportunities to reduce heat loss and energy consumption for heating should be accompanied by monitoring parameters characterizing the required thermal regime:

• Air temperature;

• Average temperature of the internal surfaces of fences;

• Air speed and relative humidity.

Axioms:
1. Heat production costs money and requires resources.
2. Magnitude heat flow is proportional to the temperature difference between the heat source and the object or room into which the heat enters, and the direction of heat flow is ALWAYS (!) from hot surface to cold
3. the main efforts are spent on increasing the resistance to the flow of heat losses
4. Heat is transferred in three ways: convection, radiation (radiation) and thermal conductivity, with convection and thermal conductivity as physical phenomena appear SIMULTANEOUSLY
5. Heat is CONSTANTLY transferred by radiation from warmer objects to colder ones in proportion to the difference in their temperatures and the distance between them.
6. Of the three main heat transfer methods, radiation is the most difficult to quantify for buildings. (!)
7. Heat losses of typical residential houses and other buildings occur in three main ways/directions (very roughly: losses through external fences, windows/doors and ventilation/infiltration), each of these three factors accounts for 20...50% of the total heat losses losses of the building, and it is almost impossible to consider them independently of each other.
8. As the share of other factors causing heat loss decreases, the penetration of outside air takes up an increasingly larger percentage of the total factors.
9. A person himself “warms” colder building structures and interior items, as well as indoor air (through convection), by radiation (slightly by thermal conductivity).
10. An increase in air speed causes an increase in the convective heat transfer coefficient. Relative humidity internal air affects the heat loss of buildings, i.e. by the amount specific heat capacity air, which is greater the higher its humidity.
11. Increasing the temperature on the internal surfaces of building structures is desirable from the point of view of reducing heat loss, as well as thermal comfort, which is expressed by the requirement: “Warm walls, cold air.”
12. When assessing thermal comfort, the temperature of the internal air directly depends on the temperature of the internal surface of the structures. Together with the indoor air temperature, it determines the total room temperature. For residential buildings the total temperature should be 38°C... etc...

Tricky question":

Does it make sense to “run around” with this heat capacity of walls/floors “like a sack”, if even in the best case we can expect (theoretically) to “cut”/compensate for heat loss by no more than 15-30%?!

"No, it doesn't!!!" - without hesitation, I will answer;
“Why?” - you ask in surprise...
And the box opens simply - WE HAVEN'T ACCOUNTED EVERYTHING!!!

Dogmas:
There are still other reasons for heat loss (windows/doors + air/ventilation) - and heat capacity/thermal inertia does not directly affect them -> and in the final calculation, these reasons can increase by 60-80%!
Maybe it still makes sense to save money by abandoning stone walls, and direct the freed funds to energy-saving windows/doors and ventilation systems? Let's think... Figuratively speaking, heat is like softened clay in your hand: you clench your fist - the clay comes out through your fingers, you try to close the gaps between your fingers on one side - and it sticks out in another place => you block the outward movement of heat through thermal conductivity, and it , “this is bad”, strives to be washed away there by radiation and/or convection along “bypass roads”, through the same “interesting” air for example....

And finally, the MOST IMPORTANT thing - producing heat costs money and requires resources!

Why produce and “drive” such expensive heat into the thermal circuit of a stone house? - after all, most of it will be encapsulated in enclosing structures, scattered (sooner or later, so external thermal insulation is not a panacea) during external environment and will not be available for “extraction”?! After all, a stone house itself as a heat accumulator has a significantly lower efficiency (at least several times) than specialized heating devices (the same brick kilns, Trombe walls, gravel-sand heat accumulators, for example).
For this, is it worth installing a heating system with increased (compared to a similar frame house) power, and then also overpaying for heating?! Are we warming the HOUSE so that it doesn’t feel cold? ...but what about a person and his needs?

Consequence-> a cold stone wall can “heat with radiation” only objects that have even more low temperature! Moreover, it turns out that the lion's share of the heat accumulated in heat-intensive structures is spent on... convective heat exchange with the internal air. In a stone house it can be arranged natural ventilation- therefore, the supply air has a low temperature - and thermal energy is wasted on heating it!

But the wall of a stone house cannot warm a person - the laws of physics: the human body temperature is 36.6 degrees, and the inner surface of the wall under normal conditions is only 18! -> i.e. a heat-intensive wall (ceiling, floor) is like an “energy vampire” that sucks heat out of you (mainly by radiation, to a lesser extent through convection and thermal conductivity).

Therefore, one should count on the rational (!) use of heat capacity only in special cases (stoves, fireplaces, heated floors and walls, Trombe walls, solar collectors, heat accumulators, etc.) and/or in special cases (“solar”, “passive” etc.) houses specially designed to capture solar (i.e. FREE!!!) heat.

Next, “Question for backfilling”: then how to explain the numerous documented facts that after turning off the heating in a frame house, even in severe frosts, the temperature drops no more than 2-5 degrees in 1-2 days, while a stone house “will freeze "in a few hours? (That is, why does a frame house not freeze out within a few hours when the heating is turned off, without having large reserves of heat in building structures??)
After all, there are no heat-intensive elements in it - what is the reason for this paradox, huh???

I believe there are several explanations for this, but one of the main reasons is because the internal heat capacity of the building is minimal, and after turning off the heating most of heat already located inside the building’s thermal circuit does not “flow pointlessly” from a “hot” person, warm air and heated heating and household appliances(radiators, stoves, electric lamps, evaporator grilles of refrigerators, TVs, etc.) deep into building structures, but remains indoors (after all, frame walls do not accumulate heat).
Of course, heat loss occurs, but it can be minimized (as in the example above), first of all, by eliminating drafts, tightly closing doors, shutters and curtains on windows (if any).
In addition, do not forget that a person himself generates heat (116 watts at room temperature, with cooling, heat loss increases - primarily due to radiation). Therefore, by adding a few weak “heating” devices (the same candles - after all, we don’t have electricity either) you can to some extent compensate for heat loss (“the main thing, boy, is to hold out until the morning” - and then help will come... in the form the warmth of the sun or an armful of logs brought from the barn for the fireplace). In such a situation, the internal surface temperature frame wall, and with it the total temperature of the room, (with LONG-TERM consideration) will remain higher than in a stone house, much longer, and thermal discomfort will also occur later.
It is clear that this raises the problem of air renewal, which largely depends on the design and planning solution of the house (we are talking about the area/volume per inhabitant and the open or isolated layout of the premises).
In a stone house in a similar situation, part of the heat accumulated in heat-intensive building structures will indeed be released into the premises - but this process will last only a few hours... while most of it, I believe, will still be dissipated into the external environment through radiation , thermal conductivity and convection.
“...Heating turned off at night means fuel saved. However, this is unlikely to reduce energy costs, because in the morning you will need to heat the air and the bedroom walls that have cooled overnight, which will lead to additional heat consumption.

In houses that have low heat capacity structures, turning off the heating at night can save a small amount of energy. In houses with heat-intensive structural elements, it is hardly advisable to lower the temperature at night, since multi-ton masonry compensates for heat loss. In the morning, she will replenish the warmth she gave away. So it’s not worth lowering the temperature at night...” (Magazine “Home” No. 1, 2007, p. 37).

We remember from physics that the heat is coming to the cold, and the outer surface of the wall, even with insulation under the influence of frost and wind, will cool faster than the inner surface, giving off heat to rooms, objects, air (through radiation within the “line of sight” and convection/thermal conduction - when cooling objects and air below the wall temperature ).

So for those who were hoping to be warmed by radiation from a stone wall “like from a Russian stove” (after all, there is so much energy stored there, in the wall!), I suggest you urgently “come to your senses” and start pulling on thick woolen leggings and looking for your grandfather’s sheepskin coat in the closet! - while a person is alive, it is HE who heats the wall/ceiling/floor with radiation (to a lesser extent by convection and thermal conductivity), but NOT the other way around!

That is, when talking about “warm walls”, we are not talking about heating as such, but only (and this is important to understand!) about REDUCING human heat loss.

Moreover, unlike a frame wall, a stone wall is the minimum heat generated by humans and our candles, as well as stored in interior items or received on a short winter day in the form solar radiation, “it will swallow it and not notice” - how could it be otherwise, it is so heat-intensive and likes to store up tens and hundreds of kJ of heat “for future use”... and then... this heat is there somewhere “walking in the depths of the wall/floor” - It probably solves some of its own problems! this is truly a “selfish energy vampire”.
Therefore, thermal discomfort in a stone house usually occurs earlier, even at the same internal air temperature as the frame frame! - because the wall is “colder” and constantly “pumps out” all the heat from the room and people.

Conclusions:
When the heating is turned off, a stone house begins to release PART of the heat accumulated in the building structures - here it really has an advantage over a frame house. In this way, the average internal temperature in the house is naturally integrated at a constant power of heating devices - the heat loss that increases at night is compensated by heat transfer from the stone wall/ceiling.
However, this process lasts only a few hours (quickly received, quickly returned), and the house itself is not the most perfect heat accumulator. Hoping for “warm” interior walls also not particularly worth it - after all, they do not hang in the air, therefore, they have a constructive connection with colder external fences (walls/ceilings/roofing/foundation) -> therefore, heat will flow there due to the thermal conductivity of the stone + convective and radiation heat exchange with air and objects interior
After this, the stone structure begins to inexorably turn into a “freezer” every hour/day, mercilessly pumping out what little heat it receives from auxiliary heating (if any), lighting/household (if there is electricity) appliances, as well as directly from the human body or through the windows from the Sun ==> therefore it is very difficult to survive in such a building while waiting for the heating to be restored. In addition, it will take several days and increased fuel costs (after all, heat-intensive walls/floors will store thermal energy - and they are very voracious)) to restore normal temperature.
U frame house There are no special reserves of heat in the walls/floors, but it is less thermally inertial and does not “store heat.” Therefore, auxiliary heating and other devices + the Sun can provide quite acceptable thermal comfort, and even restore normal temperature regime it will be possible in a few hours. It is especially important that the walls in such a house will remain warmer than stone walls in the same conditions. Frame structures will not pump out heat from a “hot” person with such enthusiasm; accordingly, heat loss from the body by radiation will be significantly less. And all this for less money...
Figuratively speaking, a stone house is a fastidious (in terms of financial costs during construction and operation) sprinter; it is able to effectively smooth out nighttime temperature fluctuations, while a frame house is an unpretentious stayer, capable of running (functioning) at a moderate speed for much longer, while possessing a certain "heating flexibility".

So: what have we come to? It is the low heat capacity of a frame house that not only allows the house to use an integrated heating system, but also REDUCE HEATING COSTS BY 2-3 TIMES!!!

And this, you see, is important...

The house must be warm! Heat capacity is the ability of materials to accumulate heat. Heat-intensive materials are heavy materials that can store a lot of heat. When warmed up, they act as an energy accumulator - they cool down for a long time, warming everything around. The presence of such materials inside the house smoothes out fluctuations in temperature and humidity and increases comfort.

What should be the temperature and humidity in the house?

The humidity level inside the house is 90% controlled by ventilation and drafts. A little steam can leak in both directions through the building envelope (2 - 8%).

Changes in indoor humidity occur sharply. For example, when a liquid spills, or when steam from the kitchen or bathroom enters the room. The softening of peaks is provided by moisture-absorbing materials (heavy materials and wood) inside the house. This creates comfort.

The normal temperature inside a house with a humidity of 55% is considered to be 21 – 23 degrees. For most people, this creates the most comfortable environment.

Temperature fluctuations inside the house occur for various reasons. For example, when there is a sharp cold snap outside, the opening outer door or windows, when turning the air conditioner on and off, changing the heating... Heavy heat-intensive materials inside the house very quickly give off heat to the air or, on the contrary, absorb it, smoothing out temperature surges.

A house with walls and ceilings made of heavy materials acquires significant thermal inertia.

What materials are heat-intensive?

The greater the mass of materials heated inside the house, the more stable the temperature (and humidity) conditions inside the house.

Heat-intensive materials are concrete, brick, gypsum, clay, sand...

If the walls and internal partitions of the house are made of brick or concrete, then comfortable conditions in terms of vapor stability and temperature stability are ensured.

If concrete floors are added, then the house can be called very heat stable. A temporary heating shutdown will not be a major cause for concern.

The rate of change in the temperature of structures under external influence will depend on the quality of insulation of heavy materials.

Building materials with low thermal inertia are wood, peat, straw, adobe. And modern ones are sip panels or similar compounds of wood and foam.

Houses in the old days and now

Previously, they were mainly built wooden houses. But in the middle of them there was always a furnace - a very massive and heat-intensive object. And the tree did a good job of smoothing out moisture peaks. Therefore, wooden huts were cozy

IN modern house the wood was replaced with an even less heat-intensive panel material - plywood with polystyrene foam. But there are no heavy objects with high heat capacity in the house. And there is nothing to absorb moisture after washing the floors...

In houses made of SIP panels, the microclimate is regulated by automatic systems. Without them, a person (and all living things) would not be very comfortable there. The heavy, heated Russian stove was replaced with a microcircuit and a motor with an impeller.

Those. ventilation and heating in a SIP house must respond very sensitively to the slightest changes in humidity and air temperature. They must monitor the situation using sensors, and constantly, day and night, work to bring it back to normal...

Differences between houses made of heavy materials and light-panel ones

It is known that any heated object emits heat. And the greater the temperature and mass of an object, the more heat it emits.

In a house made of heavy materials, infrared radiation primarily warms. It comes from heated massive walls and floors. Therefore, any blowing of warm air from the room goes unnoticed here. Radiant heat warms enough even when the air is cold. Cold air entering the room is quickly heated by massive objects.

In houses made of foam plastic panels, there is no sufficient (usual) amount of thermal radiation - infrared rays. Therefore, any draft and temperature change are especially acute there.

Though automatic system ventilation and air conditioning and combats changes in microclimate, but it cannot provide that special comfort that heavy heated walls provide.

And if the “smart” systems break down, then it will be impossible to live in such a house. Therefore, in order to maintain a microclimate acceptable for humans, redundant power supplies and microclimate systems are provided there...

It is believed that “smart” systems in light houses cope with the task assigned to them. Otherwise people wouldn't live there.

Are cheap houses profitable?

A house made of foam panels is cheaper. The panels themselves are not expensive, the foundation is lightweight, and assembly takes place in a matter of days. You can get a finished home quickly and cheaply.

If you add up these expenses over 25 years, you get an impressive amount. Then it turns out that the savings from purchasing a cheap house were lost - they were eaten up by ventilation.

Also, getting to know the shortcomings of a quickly acquired house one-on-one does not bring joy. And this is on long years. And well-being and mood are measured in much larger amounts.

So is it worth rushing? It may be better to slowly but surely build a house from heavy, heat-intensive materials. And then insulate it. The house will be comfortable, and will be ventilated by any draft. After all, for own home comfort and ecology are the main thing.

In construction, a very important characteristic is heat capacity. building materials. The thermal insulation characteristics of the walls of the building depend on it, and, accordingly, the possibility of a comfortable stay inside the building. Before you start familiarizing yourself with thermal insulation characteristics individual building materials, it is necessary to understand what heat capacity is and how it is determined.

Specific heat capacity of materials

Heat capacity is physical quantity, describing the ability of a material to accumulate temperature from a heated environment. Quantitatively, specific heat capacity is equal to the amount of energy, measured in J, required to heat a body weighing 1 kg by 1 degree.
Below is a table of the specific heat capacity of the most common materials in construction.

• type and volume of heated material (V);
• the specific heat capacity of this material (Sud);
• specific gravity (msp);
• initial and final temperatures of the material.

Heat capacity of building materials

The heat capacity of materials, the table for which is given above, depends on the density and thermal conductivity of the material.

And the thermal conductivity coefficient, in turn, depends on the size and closedness of the pores. A fine-porous material, which has a closed pore system, has greater thermal insulation and, accordingly, lower thermal conductivity than a large-porous one.

This is very easy to see using the most common materials in construction as an example. The figure below shows how the thermal conductivity coefficient and the thickness of the material influence the thermal insulation qualities of external fences.

Therefore, you cannot rely solely on the indicator of the relative density of the material, but it is worth taking into account its other characteristics.

Comparative characteristics of the heat capacity of basic building materials

In order to compare the heat capacity of the most popular building materials, such as wood, brick and concrete, it is necessary to calculate the heat capacity for each of them.

First of all, you need to decide on the specific gravity of wood, brick and concrete. It is known that 1 m3 of wood weighs 500 kg, brick - 1700 kg, and concrete - 2300 kg. If we take a wall whose thickness is 35 cm, then through simple calculations we find that the specific gravity of 1 square meter of wood will be 175 kg, brick - 595 kg, and concrete - 805 kg.
Next, we will select the temperature value at which thermal energy will accumulate in the walls. For example, this will happen on a hot summer day with an air temperature of 270C. For the selected conditions, we calculate the heat capacity of the selected materials:

1. Wall made of wood: C=SudhmuddhΔT; Sder=2.3x175x27=10867.5 (kJ);
2. Concrete wall: C=SudhmuddhΔT; Cbet = 0.84x805x27 = 18257.4 (kJ);
3. Brick wall: C=SudhmuddhΔT; Skirp = 0.88x595x27 = 14137.2 (kJ).

From the calculations made, it is clear that with the same wall thickness, concrete has the highest heat capacity, and wood has the least. What does this mean? This suggests that on a hot summer day, the maximum amount of heat will accumulate in a house made of concrete, and the least amount of heat will accumulate in a house made of concrete.

This explains the fact that in wooden house V hot weather cool, and warm in cold weather. Brick and concrete easily accumulate enough a large number of heat from the environment, but just as easily part with it.

For creating comfortable conditions In a room, it is necessary that the walls have a high heat capacity and a low thermal conductivity. In this case, the walls of the house will be able to accumulate thermal energy from the environment, but at the same time prevent the penetration of thermal radiation into the room.

It is not difficult to understand this parameter logically: the ability of a wall to accumulate thermal energy. It is absolutely clear what more wall can accumulate heat in itself, the more it can give it away.

I have not seen any indication of this parameter in any company's advertising brochure; it is silent everywhere. Why? It is quite obvious that all projects, as a rule, are designed to permanent heating. In this case, indeed, the heat capacity of the wall has little effect on the microclimate of the home.

There is always heat loss through walls. With constant heating, with constant maintenance of temperature in the rooms, these heat losses are also constantly replenished by the heating system. The design of the heating system in this case is unimportant, be it centralized heating or a constantly puffing gas boiler.

But Russia is far from Moscow and its region. 40% of the country's population heats their private homes using an ancient, proven method: a stove. There will be another book about the advantages and disadvantages of this or that heating method; there is also something to say here. And now we can rightly state that a client who contacts a construction company and chooses a design for his house from those offered, to put it simply, often gets caught up in this very issue.

Stove heating is periodic heating. The stove is heated, accumulates thermal energy in its thickness and subsequently gradually releases it into the house. Even if a water boiler is installed in the furnace and wiring is done to the batteries, the essence does not change. This heating still remains intermittent.

This is where the total heat capacity of all components of a built house is very important. The greater this heat capacity, the higher the inertia of the microclimate in residential premises.

If the total heat capacity is small, the temperature in the rooms rises quickly when the stove is heated, often significantly exceeding the comfortable one. Trying to heat the stove, the owner heats it longer, as a result the house becomes hot. The temperature drops just as quickly after heating is completed, depending on the heat loss of walls, windows, ceilings, and ventilation. The stove, although it has a certain heat capacity, is not able to accumulate enough heat to maintain a comfortable temperature for a longer period.

It’s another matter if a significant heat capacity of the walls is added to the heat capacity of the furnace. When firing a furnace, it prevents the temperature from going “off scale” by taking part of the thermal energy from the air and accumulating it in its thickness. And after heating, the accumulated heat returns to the premises more long time. This is what inertia consists of.

Planning a house with stove heating, we must never forget about the heat capacity of the walls, in general about the total heat capacity of all components. Reinforced concrete floors, for example, are also a very heat-intensive part. The same applies to partitions: if they are made of brick, then of course they have a much greater heat capacity than wooden frames.

In general, we must strive for an option that will ensure the maximum total heat capacity of all components of the house structure. I repeat: this parameter is extremely important in a house with periodic heating, and not so important with constant heating. Although, in our society with its cataclysms, all kinds of accidents involving interruption of heat supply are not uncommon, and here, again, heat-intensive houses turn out to be more resilient...

So, how is the heat capacity of walls determined? SNiP II-3-79 is also used for this. According to this standard, each material has its own heat capacity coefficient. The amount of heat that a material can accumulate is calculated using two parameters: the density of the material and its heat capacity coefficient. That is, it is necessary to multiply the density of the material by a coefficient.

Here is a selection of heat capacity values ​​for some materials from this standard with the third parameter already calculated, which determines the material’s ability to accumulate thermal energy. The table is sorted in ascending order of this calculated parameter.

It is quite obvious that the least heat-intensive material is polystyrene foam, and the most, as it turns out, is particle board. And this is not surprising, since with its density it has a high heat capacity coefficient.

Guided by this table, we can always determine the heat capacity of 1 square meter of wall. It should be noted that in this case we are not interested in its total heat capacity, but in the heat capacity of its internal part, since heat from the same furnace accumulates precisely inner surface walls, but not the outer one, bordering on the outside air.

And one more thing: the heat capacity value we calculate is just an approximate value, since the temperature of the wall itself at different points along its thickness is certainly different. However, for a comparative analysis, this approach is quite sufficient to determine the design of the future wall. After all, we do not set ourselves the task of determining the exact heat capacity; it is important for us to know only the advantage of one design over another in terms of heat capacity.

Using the example of a three-layer wall in the previous chapter, we can well estimate its useful heat capacity. 1 square meter an internal wall consisting of concrete and 10 cm thick will have the value:
T = 0.1 * 2100 = 210 kJ/m 2 * o C
where 0.1 is the wall thickness,
2100 is the third parameter in the table for concrete.

In the figure on the left, the wall is exposed to warm indoor air, and to the right, cold outdoor air. When calculating, we do not take into account the middle layer, polystyrene foam, since it has a very low heat capacity coefficient, and the outer layer of concrete does not take part in heat accumulation at all, since it is fenced off from the source of thermal energy by insulation.

And here is another diagram of a wall, where a layer of concrete is located between two layers of insulation. It is not possible to judge the sufficient useful heat capacity here, since the most heat-intensive material (concrete) is fenced off from the interior with insulation. If we take into account polystyrene foam, then 1 square meter of wall can accumulate heat only
T = 0.1 * 54 = 5,4 kJ/m 2 * o C,
that is, almost 40 times less than according to the first scheme.

Once again, I repeat that the calculations shown only serve the purpose of comparing different schemes for the ability to accumulate thermal energy and are not accurate.

Probably one of the most important components comfortable stay the temperature in the house is optimal. From this article you will learn how to calculate the heat capacity and ideal thermal conditions of a building.

Rules for calculating the heat capacity of a room

According to the norm, the average room temperature in winter should be no lower than 18 degrees (in corner rooms not lower than 20 degrees). To heat a room, radiators of sectional, panel and tubular types are mainly used. For standard heating devices, as a rule, the pressure is set from 6 to 15 atm (in buildings above 16 floors). When choosing a radiator, you need to take a closer look at its thermal power and operating pressure.

The required power to warm up the room is calculated as follows: multiply the area of ​​the room (sq. m.) by approximately 0.1 W. If there are good double-glazed windows in the room, subtract 10-20 percent from the amount you get. Well, if the room is corner, then you need to add 25 percent. The power loss of a radiator installed under a window is approximately 10 percent.

With an uninsulated box, the battery loses approximately 15-20 percent of heat. The heat transfer of one radiator section can be checked with a sales consultant or on the manufacturer’s website.

Of course, the amount of heat emanating from the heating device is affected not only by current work coolant, but also the amount of incoming water. IN common system heating, it is possible to use natural circulation water and forced (for this you need to additionally install in the system circulation pump). This also needs to be taken into account when making calculations. Thanks to this pump, water (coolant) is distributed evenly throughout the system (the temperature at the top and bottom of the radiator is the same).

Thermal power formula and other calculation options thermal regime premises

If you need more accurate calculations, then you need to use the thermal power formula. Depending on the intended purpose of the room, its thermal regime can be constant or variable. Constant thermal conditions of the premises are maintained around the clock in administrative, residential and industrial buildings. When determining the heating load, the individual heat balance of each room is taken into account. In this case, it is necessary that each heating system compensates for heat loss.

The total thermal power for the heating system, in Watts, can be determined by the formula:

Qt.m. =. Qfence + Qin – Qb

Wherein:

Qfence — is the heat loss from the enclosing structures (Watt);
Qin. - is heat loss from heating the infiltrating air that enters through windows, cracks, gates, etc. (Watt);
Qb. — heat arrival from domestic sources (W).

The heat loss of enclosing structures, (Watt), can be determined by the formula:

Qlimit. = Fnk (tв – tн) (1 +)

Wherein:

F - is with total area fencing, (sq.m.);
n - is the location coefficient of the external structure of the fence, in relation to the outside air;
k — is a special heat transfer coefficient for the fence;
tв — is the total air temperature in the room;
tн — is the temperature of the external air.

Introduced additional heat loss: =1+4+5+2+3

In this case: 1—introduced heat loss in relation to cardinal directions:

• North= 0.1 – 1,
• East = 0.1 - W,
• South-East = 0.05 – 1 =0.05 South,
• South-West = 0 – 1 =0 2 - additional heat loss for ventilation of the room, if there are two or more external walls.

In residential areas tв they add 2 degrees, in others - 2 (0.05), but 3 — additional heat loss at the entered calculated outside air temperature. Take for floors without heating (on the first floors) with tн = - 40 degrees in size 0.05. 4 – additional heat loss for special heating of through cold air through the doors to the outside. 5 - additional height of the room. For each subsequent meter more than four, take 0.02, but not more than 0.15.

Of course, when calculating heat capacity, you need to take into account that some people have to deal with winter cold indoors, while others have to cope with sweltering heat, all this due to errors in calculations and design.

It is important to ensure that additional devices adjustments on batteries (temperature taps).