Whether it is an industrial building or a residential building, you need to make competent calculations and draw up a diagram of the heating system circuit. At this stage, experts recommend paying special attention to the calculation of the possible heat load on the heating circuit, as well as the amount of fuel consumed and heat generated.

Thermal load: what is it?

This term refers to the amount of heat given off. The preliminary calculation of the heat load made it possible to avoid unnecessary costs for the purchase of components of the heating system and for their installation. Also, this calculation will help to correctly distribute the amount of heat generated economically and evenly throughout the building.

There are many nuances in these calculations. For example, the material from which the building is built, thermal insulation, region, etc. Specialists try to take into account as many factors and characteristics as possible to obtain a more accurate result.

The calculation of the heat load with errors and inaccuracies leads to inefficient operation of the heating system. It even happens that you have to redo sections of an already working structure, which inevitably leads to unplanned expenses. Yes, and housing and communal organizations calculate the cost of services based on data on heat load.

Main Factors

An ideally calculated and designed heating system must maintain the set temperature in the room and compensate for the resulting heat losses. When calculating the indicator of the heat load on the heating system in the building, you need to take into account:

Purpose of the building: residential or industrial.

Characteristics of the structural elements of the structure. These are windows, walls, doors, roof and ventilation system.

Housing dimensions. The larger it is, the more powerful the heating system should be. Be sure to take into account the area of ​​window openings, doors, exterior walls and the volume of each interior space.

The presence of rooms for special purposes (bath, sauna, etc.).

Degree of equipment technical devices. That is, the presence of hot water supply, ventilation systems, air conditioning and the type of heating system.

For a single room. For example, in rooms intended for storage, it is not necessary to maintain a comfortable temperature for a person.

Number of points with feed hot water. The more of them, the more the system is loaded.

Area of ​​glazed surfaces. Rooms with French windows lose a significant amount of heat.

Additional terms. In residential buildings, this can be the number of rooms, balconies and loggias and bathrooms. In industrial - the number of working days in a calendar year, shifts, technological chain production process etc.

Climatic conditions of the region. When calculating heat losses, street temperatures are taken into account. If the differences are insignificant, then a small amount of energy will be spent on compensation. While at -40 ° C outside the window it will require significant expenses.

Features of existing methods

The parameters included in the calculation of the heat load are in SNiPs and GOSTs. They also have special heat transfer coefficients. From the passports of the equipment included in the heating system, digital characteristics are taken regarding certain radiator heating, boiler, etc. And also traditionally:

The heat consumption, taken to the maximum for one hour of operation of the heating system,

The maximum heat flow from one radiator,

Total heat costs in a certain period (most often - a season); if you need an hourly calculation of the load on heating network, then the calculation must be carried out taking into account the temperature difference during the day.

The calculations made are compared with the heat transfer area of ​​the entire system. The index is quite accurate. Some deviations happen. For example, for industrial buildings, it will be necessary to take into account the reduction in heat energy consumption on weekends and holidays, and in residential buildings - at night.

Methods for calculating heating systems have several degrees of accuracy. To reduce the error to a minimum, it is necessary to use rather complex calculations. Less accurate schemes are used if the goal is not to optimize the cost of heating system.

Basic calculation methods

To date, the calculation of the heat load on the heating of a building can be carried out in one of the following ways.

Three main

1. Aggregated indicators are taken for calculation.
2. The indicators of the structural elements of the building are taken as the base. Here, the calculation of the internal volume of air going to warm up will also be important.
3. All objects included in the heating system are calculated and summarized.

One exemplary

There is also a fourth option. It has a fairly large error, because the indicators are taken very average, or they are not enough. Here is the formula - Q from \u003d q 0 * a * V H * (t EH - t NPO), where:

• q 0 - specific thermal characteristic buildings (most often determined by the coldest period),
• a - correction factor (depends on the region and is taken from ready-made tables),
• V H is the volume calculated from the outer planes.

Example of a simple calculation

For building with standard parameters(ceiling heights, room sizes and good thermal insulation characteristics) you can apply a simple ratio of parameters, corrected by a factor depending on the region.

Suppose that a residential building is located in the Arkhangelsk region, and its area is 170 square meters. m. The heat load will be equal to 17 * 1.6 \u003d 27.2 kW / h.

Such a definition of thermal loads does not take into account many important factors. For example, design features buildings, temperatures, the number of walls, the ratio of the areas of walls and window openings, etc. Therefore, such calculations are not suitable for serious heating system projects.

It depends on the material from which they are made. Most often today, bimetallic, aluminum, steel are used, much less often cast iron radiators. Each of them has its own heat transfer index (thermal power). Bimetallic radiators with a distance between the axes of 500 mm, on average, have 180 - 190 watts. Aluminum radiators have almost the same performance.

The heat transfer of the described radiators is calculated for one section. Steel plate radiators are non-separable. Therefore, their heat transfer is determined based on the size of the entire device. For example, the thermal power of a two-row radiator 1100 mm wide and 200 mm high will be 1010 W, and a steel panel radiator 500 mm wide and 220 mm high will be 1644 W.

The calculation of the heating radiator by area includes the following basic parameters:

Ceiling height (standard - 2.7 m),

Thermal power (per sq. m - 100 W),

One outer wall.

These calculations show that for every 10 sq. m requires 1,000 W of thermal power. This result is divided by the heat output of one section. The answer is required amount radiator sections.

For the southern regions of our country, as well as for the northern ones, decreasing and increasing coefficients have been developed.

Average calculation and exact

Given the factors described, the average calculation is carried out according to the following scheme. If for 1 sq. m required 100W heat flow, then a room of 20 sq. m should receive 2,000 watts. The radiator (popular bimetallic or aluminum) of eight sections allocates about Divide 2,000 by 150, we get 13 sections. But this is a rather enlarged calculation of the thermal load.

The exact one looks a little intimidating. Actually, nothing complicated. Here is the formula:

Q t \u003d 100 W / m 2 × S (rooms) m 2 × q 1 × q 2 × q 3 × q 4 × q 5 × q 6 × q 7, where:

• q 1 - type of glazing (ordinary = 1.27, double = 1.0, triple = 0.85);
• q 2 - wall insulation (weak or absent = 1.27, 2-brick wall = 1.0, modern, high = 0.85);
• q 3 - the ratio of the total area of ​​window openings to the floor area (40% = 1.2, 30% = 1.1, 20% - 0.9, 10% = 0.8);
• q 4 - outdoor temperature (the minimum value is taken: -35 o C = 1.5, -25 o C = 1.3, -20 o C = 1.1, -15 o C = 0.9, -10 o C = 0.7);
• q 5 - the number of external walls in the room (all four = 1.4, three = 1.3, corner room= 1.2, one = 1.2);
• q 6 - type of calculation room above the calculation room (cold attic = 1.0, warm attic = 0.9, residential heated room = 0.8);
• q 7 - ceiling height (4.5 m = 1.2, 4.0 m = 1.15, 3.5 m = 1.1, 3.0 m = 1.05, 2.5 m = 1.3).

Using any of the methods described, it is possible to calculate the heat load of an apartment building.

Approximate calculation

These are the conditions. The minimum temperature in the cold season is -20 ° C. Room 25 sq. m with triple glazing, double-leaf windows, ceiling height of 3.0 m, two-brick walls and an unheated attic. The calculation will be as follows:

Q \u003d 100 W / m 2 × 25 m 2 × 0.85 × 1 × 0.8 (12%) × 1.1 × 1.2 × 1 × 1.05.

The result, 2 356.20, is divided by 150. As a result, it turns out that 16 sections need to be installed in a room with the specified parameters.

If calculation is required in gigacalories

In the absence of a heat energy meter on an open heating circuit, the calculation of the heat load for heating the building is calculated by the formula Q \u003d V * (T 1 - T 2) / 1000, where:

• V - the amount of water consumed by the heating system, calculated in tons or m 3,
• T 1 - a number showing the temperature of hot water, measured in o C, and for calculations, the temperature corresponding to a certain pressure in the system is taken. This indicator has its own name - enthalpy. If it is not possible to remove temperature indicators in a practical way, they resort to an average indicator. It is in the range of 60-65 o C.
• T 2 - temperature of cold water. It is quite difficult to measure it in the system, so constant indicators have been developed that depend on temperature regime on the street. For example, in one of the regions, in the cold season, this indicator is taken equal to 5, in summer - 15.
• 1,000 is the coefficient for obtaining the result immediately in gigacalories.

In the case of a closed circuit, the heat load (gcal/h) is calculated differently:

Q from \u003d α * q o * V * (t in - t n.r.) * (1 + K n.r.) * 0.000001, where

The calculation of the heat load turns out to be somewhat enlarged, but it is this formula that is given in the technical literature.

Increasingly, in order to increase the efficiency of the heating system, they resort to buildings.

These works are carried out at night. For a more accurate result, you must observe the temperature difference between the room and the street: it must be at least 15 o. Fluorescent and incandescent lamps are switched off. It is advisable to remove carpets and furniture to the maximum, they knock down the device, giving some error.

The survey is carried out slowly, the data are recorded carefully. The scheme is simple.

The first stage of work takes place indoors. The device is moved gradually from doors to windows, giving Special attention corners and other joints.

The second stage is the examination of the external walls of the building with a thermal imager. The joints are still carefully examined, especially the connection with the roof.

The third stage is data processing. First, the device does this, then the readings are transferred to a computer, where the corresponding programs complete the processing and give the result.

If the survey was conducted by a licensed organization, then it will issue a report with mandatory recommendations based on the results of the work. If the work was carried out personally, then you need to rely on your knowledge and, possibly, the help of the Internet.

Designing and thermal calculation of the heating system is an obligatory stage in the arrangement of home heating. The main task of the computational measures is to determine the optimal parameters of the boiler and the radiator system.

Agree, at first glance it may seem that only an engineer can carry out a heat engineering calculation. However, not everything is so difficult. Knowing the algorithm of actions, it will be possible to independently perform the necessary calculations.

The article details the calculation procedure and provides all the necessary formulas. For a better understanding, we have prepared an example of a thermal calculation for a private house.

The classical thermal calculation of the heating system is a summary technical document that includes the required step-by-step standard calculation methods.

But before studying these calculations of the main parameters, you need to decide on the concept of the heating system itself.

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The heating system is characterized by forced supply and involuntary removal of heat in the room.

The main tasks of calculating and designing a heating system:

• most reliably determine heat losses;
• determine the amount and conditions for the use of the coolant;
• select the elements of generation, movement and heat transfer as accurately as possible.

But the room temperature in winter is provided by the heating system. Therefore, we are interested in temperature ranges and their deviation tolerances for the winter season.

Most normative documents the following temperature ranges are specified, which allow a person to be comfortable in the room.

For non-residential premises of office type with an area of ​​up to 100 m 2:

• 22-24°С — optimum temperature air;
• 1°C- allowable fluctuation.

For office-type premises with an area of ​​​​more than 100 m 2, the temperature is 21-23 ° C. For non-residential premises of an industrial type, the temperature ranges vary greatly depending on the purpose of the premises and the established labor protection standards.

Comfortable room temperature for each person "own". Someone likes to be very warm in the room, someone is comfortable when the room is cool - it's all quite individual

As for residential premises: apartments, private houses, estates, etc., there are certain temperature ranges that can be adjusted depending on the wishes of the residents.

And yet, for specific premises of an apartment and a house, we have:

• 20-22°C- residential, including children's, room, tolerance ± 2 ° С -
• 19-21°C- kitchen, toilet, tolerance ± 2 ° С;
• 24-26°C- bath, shower, swimming pool, tolerance ± 1 ° С;
• 16-18°C— corridors, hallways, stairwells, storerooms, tolerance +3°С

It is important to note that there are several more basic parameters that affect the temperature in the room and that you need to focus on when calculating the heating system: humidity (40-60%), oxygen concentration and carbon dioxide in the air (250:1), the speed of movement of air masses (0.13-0.25 m / s), etc.

Calculation of heat loss in the house

According to the second law of thermodynamics (school physics), there is no spontaneous transfer of energy from less heated to more heated mini or macro objects. A special case of this law is the "desire" to create a temperature equilibrium between two thermodynamic systems.

For example, the first system is an environment with a temperature of -20°C, the second system is a building with an internal temperature of +20°C. According to the above law, these two systems will tend to balance through the exchange of energy. This will happen with the help of heat losses from the second system and cooling in the first.

We can definitely say that the ambient temperature depends on the latitude at which it is located. a private house. And the temperature difference affects the amount of heat leakage from the building (+)

By heat loss is meant an involuntary release of heat (energy) from some object (house, apartment). For an ordinary apartment, this process is not so “noticeable” in comparison with a private house, since the apartment is located inside the building and “adjacent” to other apartments.

In a private house, heat “leaves” to one degree or another through the external walls, floor, roof, windows and doors.

Knowing the amount of heat loss for the most adverse weather conditions and the characteristics of these conditions, it is possible to calculate the power of the heating system with high accuracy.

So, the volume of heat leakage from the building is calculated by the following formula:

Q=Q floor +Q wall +Q window +Q roof +Q door +…+Q i, where

qi- the volume of heat loss from a homogeneous type of building envelope.

Each component of the formula is calculated by the formula:

Q=S*∆T/R, where

• Q– thermal leakage, V;
• S- the area of ​​a particular type of structure, sq. m;
• ∆T– temperature difference between the ambient air and indoors, °C;
• R- thermal resistance of a certain type of construction, m 2 * ° C / W.

The very value of thermal resistance for actually existing materials is recommended to be taken from auxiliary tables.

In addition, thermal resistance can be obtained using the following relationship:

R=d/k, where

• R- thermal resistance, (m 2 * K) / W;
• k- coefficient of thermal conductivity of the material, W / (m 2 * K);
• d is the thickness of this material, m.

In old houses with a damp roof structure, heat leakage occurs through the upper part of the building, namely through the roof and attic. Carrying out activities on or solve the problem.

If insulated attic space and the roof, then the total heat loss from the house can be significantly reduced

There are several more types of heat losses in the house through cracks in the structures, the ventilation system, kitchen hood, opening windows and doors. But it makes no sense to take into account their volume, since they make up no more than 5% of total number major heat leaks.

Boiler power determination

To maintain the temperature difference between the environment and the temperature inside the house, it is necessary autonomous system heating, which maintains the desired temperature in every room of a private house.

The basis of the heating system is different: liquid or solid fuel, electric or gas.

The boiler is the central node of the heating system that generates heat. The main characteristic of the boiler is its power, namely the rate of conversion of the amount of heat per unit of time.

Having calculated the heat load for heating, we obtain the required nominal power of the boiler.

For an ordinary multi-room apartment, the boiler power is calculated through the area and specific power:

P boiler \u003d (S rooms * P specific) / 10, where

• S premises— total area heated room;
• R specific- specific power relative to climatic conditions.

But this formula does not take into account heat losses, which are sufficient in a private house.

There is another ratio that takes this parameter into account:

P boiler \u003d (Q losses * S) / 100, where

• Boiler P- boiler power;
• Q loss— heat loss;
• S- heated area.

The rated power of the boiler must be increased. The reserve is necessary if it is planned to use the boiler for heating water for the bathroom and kitchen.

In most heating systems of private houses, it is recommended to use an expansion tank, in which the supply of coolant will be stored. Every private house needs hot water supply

In order to provide for a boiler power reserve, the safety factor K must be added to the last formula:

P boiler \u003d (Q losses * S * K) / 100, where

To- will be equal to 1.25, that is, the calculated power of the boiler will be increased by 25%.

Thus, the power of the boiler makes it possible to maintain standard temperature air in the rooms of the building, as well as to have an initial and additional volume of hot water in the house.

Features of the selection of radiators

Radiators, panels, underfloor heating systems, convectors, etc. are standard components for providing heat in a room. The most common parts of a heating system are radiators.

The heat sink is a special hollow construction modular type alloy with high heat dissipation. It is made of steel, aluminum, cast iron, ceramics and other alloys. The principle of operation of the heating radiator is reduced to the radiation of energy from the coolant into the space of the room through the "petals".

aluminum and bimetal radiator heating replaced massive cast-iron batteries. Ease of production, high heat dissipation, good construction and design have made this product a popular and widespread tool for radiating heat in a room.

There are several methods in the room. The following list of methods is sorted in order of increasing accuracy of calculations.

Calculation options:

1. By area. N \u003d (S * 100) / C, where N is the number of sections, S is the area of ​​\u200b\u200bthe room (m 2), C is the heat transfer of one section of the radiator (W, taken from those passports or certificates for the product), 100 W is the amount of heat flow , which is necessary for heating 1 m 2 (empirical value). The question arises: how to take into account the height of the ceiling of the room?
2. By volume. N=(S*H*41)/C, where N, S, C are similar. H is the height of the room, 41 W is the amount of heat flow that is necessary to heat 1 m 3 (empirical value).
3. By odds. N=(100*S*k1*k2*k3*k4*k5*k6*k7)/C, where N, S, C and 100 are similar. k1 - taking into account the number of cameras in the double-glazed window of the room window, k2 - thermal insulation of the walls, k3 - the ratio of the window area to the area of ​​​​the room, k4 - average subzero temperature in the coldest week of winter, k5 is the number of external walls of the room (which "facing" to the street), k6 is the type of room from above, k7 is the height of the ceiling.

This is the most accurate option for calculating the number of sections. Naturally, fractional calculation results are always rounded to the next integer.

Hydraulic calculation of water supply

Of course, the “picture” of calculating heat for heating cannot be complete without calculating such characteristics as the volume and speed of the coolant. In most cases, the coolant is ordinary water in a liquid or gaseous state of aggregation.

The actual volume of the coolant is recommended to be calculated by summing up all the cavities in the heating system. When using a single-circuit boiler, this is best option. When using double-circuit boilers in the heating system, it is necessary to take into account the consumption of hot water for hygienic and other domestic purposes

Calculation of the volume of water heated by a double-circuit boiler to provide residents hot water and heating of the coolant, is made by summing up the internal volume of the heating circuit and the real needs of users in heated water.

The volume of hot water in the heating system is calculated by the formula:

W=k*P, where

• W is the volume of the heat carrier;
• P- power of the heating boiler;
• k- power factor (number of liters per unit of power, equal to 13.5, range - 10-15 liters).

As a result, the final formula looks like this:

W=13.5*P

The coolant velocity is the final dynamic assessment of the heating system, which characterizes the rate of fluid circulation in the system.

This value helps to evaluate the type and diameter of the pipeline:

V=(0.86*P*μ)/∆T, where

• P- boiler power;
• μ — boiler efficiency;
• ∆T is the temperature difference between the supply water and the return water.

Using the above methods, it will be possible to obtain real parameters that are the "foundation" of the future heating system.

Thermal calculation example

As an example of a thermal calculation, there is an ordinary 1-storey house with four living rooms, a kitchen, a bathroom, winter Garden» and utility rooms.

Foundation made of monolithic reinforced concrete slab(20 cm), external walls - concrete (25 cm) with plaster, roof - ceilings made of wooden beams, roof - metal tile and mineral wool (10 cm)

Let us designate the initial parameters of the house necessary for the calculations.

Building dimensions:

• floor height - 3 m;
• small window of the front and back of the building 1470 * 1420 mm;
• large facade window 2080*1420 mm;
• entrance doors 2000*900 mm;
• rear doors (exit to the terrace) 2000*1400 (700 + 700) mm.

The total width of the building is 9.5 m 2 , length 16 m 2 . Heating will only living rooms(4 pcs.), bathroom and kitchen.

For an accurate calculation of heat loss on the walls, the area of ​​\u200b\u200ball windows and doors must be subtracted from the area of ​​\u200b\u200bthe external walls - this is a completely different type of material with its own thermal resistance

We start by calculating the areas of homogeneous materials:

• floor area - 152 m 2;
• roof area - 180 m 2, given the height of the attic 1.3 m and the width of the run - 4 m;
• window area - 3 * 1.47 * 1.42 + 2.08 * 1.42 \u003d 9.22 m 2;
• door area - 2 * 0.9 + 2 * 2 * 1.4 \u003d 7.4 m 2.

The area of ​​the outer walls will be equal to 51*3-9.22-7.4=136.38 m2.

We turn to the calculation of heat loss on each material:

• Q floor \u003d S * ∆T * k / d \u003d 152 * 20 * 0.2 / 1.7 \u003d 357.65 W;
• Q roof \u003d 180 * 40 * 0.1 / 0.05 \u003d 14400 W;
• Q window \u003d 9.22 * 40 * 0.36 / 0.5 \u003d 265.54 W;
• Q door =7.4*40*0.15/0.75=59.2W;

And also Q wall is equivalent to 136.38*40*0.25/0.3=4546. The sum of all heat losses will be 19628.4 W.

As a result, we calculate the boiler power: P boiler \u003d Q losses * S heating_rooms * K / 100 \u003d 19628.4 * (10.4 + 10.4 + 13.5 + 27.9 + 14.1 + 7.4) * 1.25 / 100 \u003d 19628.4 * 83.7 * 1.25 / 100 \u003d 20536.2 \u003d 21 kW.

Let's calculate the number of radiator sections for one of the rooms. For all others, the calculations are similar. For example, a corner room (on the left, lower corner of the diagram) has an area of ​​10.4 m2.

So N=(100*k1*k2*k3*k4*k5*k6*k7)/C=(100*10.4*1.0*1.0*0.9*1.3*1.2*1.0*1.05)/180=8.5176=9.

This room requires 9 sections of a heating radiator with a heat output of 180 watts.

We proceed to the calculation of the amount of coolant in the system - W=13.5*P=13.5*21=283.5 l. This means that the coolant velocity will be: V=(0.86*P*μ)/∆T=(0.86*21000*0.9)/20=812.7 l.

As a result, the full turnover of the entire volume of the coolant in the system will be equivalent to 2.87 times per hour.

A selection of articles on thermal calculation will help determine the exact parameters of the elements of the heating system:

Conclusions and useful video on the topic

A simple calculation of the heating system for a private house is presented in the following overview:

All the subtleties and generally accepted methods for calculating the heat loss of a building are shown below:

Another option for calculating heat leakage in a typical private house:

This video talks about the features of the circulation of an energy carrier for heating a home:

The thermal calculation of the heating system is individual in nature, it must be carried out competently and accurately. The more accurate the calculations are made, the less the owners will have to overpay country house during operation.

Do you have experience in performing thermal calculation of the heating system? Or have questions about the topic? Please share your opinion and leave comments. The feedback block is located below.

Before proceeding with the purchase of materials and the installation of heat supply systems for a house or apartment, it is necessary to calculate the heating based on the area of ​​\u200b\u200beach room. Basic parameters for heating design and heat load calculation:

• Square;
• Number of window blocks;
• Ceiling height;
• The location of the room;
• Heat loss;
• Heat dissipation of radiators;
• Climatic zone (outside temperature).

The method described below is used to calculate the number of batteries for a room area without additional heating sources (heat-insulated floors, air conditioners, etc.). There are two ways to calculate heating: using a simple and complicated formula.

Before starting the design of heat supply, it is worth deciding which radiators will be installed. The material from which the heating batteries are made:

• Cast iron;
• Steel;
• Aluminum;
• Bimetal.

Aluminum and bimetallic radiators are considered the best option. The highest thermal output of bimetallic devices. Cast iron batteries heat up for a long time, but after turning off the heating, the temperature in the room lasts for quite a long time.

A simple formula for designing the number of sections in a heating radiator is:

K = Sx(100/R), where:

S is the area of ​​the room;

R - section power.

If we consider the example with the data: room 4 x 5 m, bimetallic radiator, power 180 watts. The calculation will look like this:

K = 20*(100/180) = 11.11. So, for a room with an area of ​​20 m 2, a battery with at least 11 sections is required for installation. Or, for example, 2 radiators with 5 and 6 ribs. The formula is used for rooms with a ceiling height of up to 2.5 m in a standard Soviet-built building.

However, such a calculation of the heating system does not take into account the heat loss of the building, the outdoor temperature of the house and the number of window blocks are also not taken into account. Therefore, these coefficients should also be taken into account for the final refinement of the number of ribs.

Calculations for panel radiators

In the case where the installation of a battery with a panel instead of ribs is supposed, the following formula by volume is used:

W \u003d 41xV, where W is the battery power, V is the volume of the room. The number 41 is the norm of the average annual heating capacity of 1 m 2 of a dwelling.

As an example, we can take a room with an area of ​​​​20 m 2 and a height of 2.5 m. The value of the radiator power for a room volume of 50 m 3 will be 2050 W, or 2 kW.

Heat loss calculation

H2_2

The main heat loss occurs through the walls of the room. To calculate, you need to know the coefficient of thermal conductivity of the external and inner material from which the house is built, the thickness of the wall of the building is also important average temperature outside air. Basic formula:

Q \u003d S x ΔT / R, where

ΔT is the temperature difference between the outside and the internal optimum value;

S is the area of ​​the walls;

R is the thermal resistance of the walls, which, in turn, is calculated by the formula:

R = B/K, where B is the thickness of the brick, K is the coefficient of thermal conductivity.

Calculation example: the house is built of shell rock, in stone, located in the Samara region. The thermal conductivity of the shell rock is on average 0.5 W / m * K, the wall thickness is 0.4 m. Considering the average range, minimum temperature-30 °C in winter. In the house, according to SNIP, normal temperature is +25 °C, the difference is 55 °C.

If the room is angular, then both of its walls are in direct contact with the environment. The area of ​​the outer two walls of the room is 4x5 m and 2.5 m high: 4x2.5 + 5x2.5 = 22.5 m 2.

R = 0.4/0.5 = 0.8

Q \u003d 22.5 * 55 / 0.8 \u003d 1546 W.

In addition, it is necessary to take into account the insulation of the walls of the room. When finishing with foam plastic of the outer area, heat loss is reduced by about 30%. So, the final figure will be about 1000 watts.

Heat Load Calculation (Advanced Formula)

Scheme of heat loss of premises

To calculate the final heat consumption for heating, it is necessary to take into account all the coefficients according to the following formula:

CT \u003d 100xSxK1xK2xK3xK4xK5xK6xK7, where:

S is the area of ​​the room;

K - various coefficients:

K1 - loads for windows (depending on the number of double-glazed windows);

K2 - thermal insulation of the outer walls of the building;

K3 - loads for the ratio of window area to floor area;

K4 – outdoor air temperature regime;

K5 - taking into account the number of external walls of the room;

K6 - loads, based on the upper room above the calculated room;

K7 - taking into account the height of the room.

As an example, we can consider the same room of a building in the Samara region, insulated from the outside with foam plastic, having 1 double-glazed window, above which a heated room is located. The heat load formula will look like this:

KT \u003d 100 * 20 * 1.27 * 1 * 0.8 * 1.5 * 1.2 * 0.8 * 1 \u003d 2926 W.

The calculation of heating is focused on this figure.

Heat consumption for heating: formula and adjustments

Based on the above calculations, 2926 watts are needed to heat a room. Considering heat losses, the requirements are: 2926 + 1000 = 3926 W (KT2). The following formula is used to calculate the number of sections:

K = KT2/R, where KT2 is the final value of the heat load, R is the heat transfer (power) of one section. Final figure:

K = 3926/180 = 21.8 (rounded 22)

So, in order to ensure optimal heat consumption for heating, it is necessary to install radiators with a total of 22 sections. It must be taken into account that the most low temperature- 30 degrees of frost in time is a maximum of 2-3 weeks, so you can safely reduce the number to 17 sections (- 25%).

If homeowners are not satisfied with such an indicator of the number of radiators, then batteries with a large heat supply capacity should be taken into account initially. Or insulate the walls of the building both inside and outside modern materials. In addition, it is necessary to correctly assess the needs of housing for heat, based on secondary parameters.

There are several other parameters that affect the additional energy wasted, which entails an increase in heat loss:

1. Features of the outer walls. Heating energy should be enough not only for heating the room, but also to compensate for heat losses. The wall in contact with the environment, over time, from changes in the temperature of the outside air, begins to let moisture in. Especially it is necessary to insulate well and carry out high-quality waterproofing for the northern directions. It is also recommended to insulate the surface of houses located in humid regions. High annual rainfall will inevitably lead to increased heat losses.
2. Place of installation of radiators. If the battery is mounted under a window, then heating energy leaks through its structure. The installation of high-quality blocks will help reduce heat loss. You also need to calculate the power of the device installed in the window sill - it should be higher.
3. Conventional annual heat demand for buildings in different time zones. As a rule, according to SNIPs, the average temperature (annual average) for buildings is calculated. However, heat demand is significantly lower if, for example, cold weather and low outdoor air values ​​occur for a total of 1 month of the year.

Advice! In order to minimize the need for heat in winter, it is recommended to install additional sources of indoor air heating: air conditioners, mobile heaters, etc.

In the cold season in our country, the heating of buildings and structures is one of the main cost items of any enterprise. And here it does not matter whether it is a residential, industrial or warehouse space. Everywhere you need to maintain a constant positive temperature so that people do not freeze, equipment does not fail, or products or materials do not deteriorate. In some cases, it is required to calculate the heat load for heating a particular building or the entire enterprise as a whole.

In what cases is the calculation of the heat load

• to optimize heating costs;
• to reduce the calculated heat load;
• in the event that the composition of heat-consuming equipment has changed (heaters, ventilation systems, etc.);
• to confirm the calculated limit on consumed heat energy;
• in the case of designing your own heating system or heat supply point;
• if there are sub-subscribers consuming thermal energy, for its correct distribution;
• In case of connection to the heating system of new buildings, structures, industrial complexes;
• to revise or conclude a new contract with an organization supplying heat energy;
• if the organization has received a notification requiring clarification thermal loads in non-residential premises;
• if the organization has the opportunity to install heat meters;
• in the event of an increase in heat consumption for unknown reasons.

On what basis can the heat load on the heating of the building be recalculated?

Order of the Ministry of Regional Development No. 610 dated December 28, 2009 "On approval of the rules for establishing and changing (revising) heat loads"() establishes the right of heat consumers to calculate and recalculate heat loads. Also, such a clause is usually present in every contract with a heat supply organization. If there is no such clause, discuss with your lawyers the issue of including it in the contract.

However, in order to revise the contractual amounts of consumed heat energy, a technical report must be submitted with the calculation of new heat loads for heating the building, in which justifications for reducing heat consumption should be given. In addition, the recalculation of thermal loads is carried out after such events as:

• overhaul of the building;
• reconstruction of internal engineering networks;
• increasing the thermal protection of the facility;
• other energy saving measures.

Method of calculation

To calculate or recalculate the heat load on the heating of buildings already in operation or newly connected to the heating system, the following work is carried out:

1. Collection of initial data about the object.
2. Conducting an energy audit of the building.
3. Based on the information obtained after the survey, the heat load for heating, hot water and ventilation is calculated.
4. Drawing up a technical report.
5. Coordination of the report in the organization providing heat energy.
6. Signing a new contract or changing the terms of an old one.

Collection of initial data on the heat load object

What data needs to be collected or received:

1. Agreement (copy) for heat supply with all annexes.
2. A certificate issued on company letterhead on the actual number of employees (in the case of industrial buildings) or residents (in the case of a residential building).
3. BTI plan (copy).
4. Data on the heating system: one-pipe or two-pipe.
5. Top or bottom filling of the heat carrier.

All these data are required, because. based on them, the heat load will be calculated, as well as all the information will be included in the final report. The initial data, in addition, will help determine the timing and volume of work. The cost of the calculation is always individual and may depend on factors such as:

• area of ​​heated premises;
• type of heating system;
• availability of hot water supply and ventilation.

Energy audit of the building

Energy audit involves the departure of specialists directly to the facility. This is necessary in order to conduct a complete inspection of the heating system, to check the quality of its insulation. Also, during the departure, the missing data about the object are collected, which cannot be obtained except by means visual inspection. The types of heating radiators used, their location and number are determined. A diagram is drawn and photographs are attached. The supply pipes must be inspected, their diameter is measured, the material from which they are made is determined, how these pipes are connected, where the risers are located, etc.

As a result of such an energy audit (energy audit), the customer will receive a detailed technical report, and on the basis of this report, the calculation of the heat loads for heating the building will be carried out.

Technical report

The technical report on the heat load calculation should consist of the following sections:

1. Initial data about the object.
2. Scheme of the location of heating radiators.
3. DHW outlet points.
4. The calculation itself.
5. Conclusion based on the results of the energy audit, which should include a comparative table of the maximum current thermal loads and contractual ones.
6. Applications.
   1. Certificate of membership in the SRO energy auditor.
   2. Floor plan of the building.
   3. Explication.
   4. All appendices to the contract for energy supply.

After drawing up, the technical report must be agreed with the heat supply organization, after which changes are made to the current contract or a new one is concluded.

An example of calculating the thermal loads of a commercial facility

This room is on the first floor of a 4-storey building. Location - Moscow.

Initial data for the object

Address of the object	Moscow city
Floors of the building	4 floors
The floor on which the surveyed premises are located	the first
The area of ​​the surveyed premises	112.9 sq.m.
Floor height	3.0 m
Heating system	Single pipe
temperature graph	95-70 deg. FROM
Estimated temperature chart for the floor on which the room is located	75-70 deg. FROM
Bottling type	Upper
Estimated indoor air temperature	+ 20 degrees C
Heating radiators, type, quantity	Cast iron radiators M-140-AO - 6 pcs. Radiator bimetallic Global (Global) - 1 pc.
Diameter of pipes of the heating system	Du-25 mm
Heating supply line length	L = 28.0 m.
DHW	missing
Ventilation	missing
0.02/47.67 Gcal

Estimated heat transfer installed radiators heating, taking into account all losses, amounted to 0.007457 Gcal/hour.

The maximum heat energy consumption for space heating was 0.001501 Gcal/h.

The final maximum consumption is 0.008958 Gcal/hour or 23 Gcal/year.

As a result, we calculate the annual savings for heating this room: 47.67-23 = 24.67 Gcal / year. Thus, it is possible to reduce the cost of heat energy by almost half. And if we take into account that the current average cost of Gcal in Moscow is 1.7 thousand rubles, then the annual savings in monetary terms will be 42 thousand rubles.

Calculation formula in Gcal

The calculation of the heat load on the heating of the building in the absence of heat meters is carried out according to the formula Q \u003d V * (T1 - T2) / 1000, where:

• V- the volume of water consumed by the heating system is measured in tons or cubic meters,
• T1- hot water temperature. It is measured in C (degrees Celsius) and the temperature corresponding to a certain pressure in the system is taken for calculations. This indicator has its own name - enthalpy. If it is impossible to accurately determine the temperature, then average values ​​\u200b\u200bof 60-65 C are used.
• T2- temperature of cold water. Often it is almost impossible to measure it, and in this case constant indicators are used, which depend on the region. For example, in one of the regions, in the cold season, the indicator will be 5, in the warm season - 15.
• 1 000 - coefficient for obtaining the result of the calculation in Gcal.

For a heating system with a closed circuit, the heat load (Gcal / h) is calculated in a different way: Qot \u003d α * qo * V * (tin - tn.r) * (1 + Kn.r) * 0.000001, where:

• α - a coefficient designed to correct climatic conditions. It is taken into account if the street temperature differs from -30 C;
• V- the volume of the building according to external measurements;
• qo- specific heating index of the building at a given tn.r = -30 C, measured in Kcal / m3 * C;
• tv is the calculated internal temperature in the building;
• tn.r- estimated street temperature for drafting a heating system;
• Kn.r is the infiltration coefficient. It is due to the ratio of heat losses of the calculated building with infiltration and heat transfer through external structural elements at the street temperature, which is set within the framework of the project being drawn up.

Calculation for heating radiators per area

Enlarged calculation

If for 1 sq.m. area requires 100 W of thermal energy, then a room of 20 sq.m. should receive 2,000 watts. A typical eight-section radiator puts out about 150 watts of heat. We divide 2,000 by 150, we get 13 sections. But this is a rather enlarged calculation of the thermal load.

Accurate calculation

The exact calculation is carried out according to the following formula: Qt = 100 W/sq.m. × S(rooms) sq.m. × q1 × q2 × q3 × q4 × q5 × q6 × q7, where:

• q1- type of glazing: ordinary = 1.27; double = 1.0; triple = 0.85;
• q2– wall insulation: weak or absent = 1.27; wall laid out in 2 bricks = 1.0, modern, high = 0.85;
• q3- the ratio of the total area of ​​window openings to the floor area: 40% = 1.2; 30% = 1.1; 20% - 0.9; 10% = 0.8;
• q4- minimum outdoor temperature: -35 C = 1.5; -25 C \u003d 1.3; -20 C = 1.1; -15 C \u003d 0.9; -10 C = 0.7;
• q5- the number of external walls in the room: all four = 1.4, three = 1.3, corner room = 1.2, one = 1.2;
• q6- type of design room above the design room: cold attic = 1.0, warm attic = 0.9, residential heated room = 0.8;
• q7- ceiling height: 4.5 m = 1.2; 4.0 m = 1.15; 3.5 m = 1.1; 3.0 m = 1.05; 2.5 m = 1.3.

On the initial stage arrangement of the heat supply system of any of the real estate objects, the design of the heating structure and the corresponding calculations are carried out. It is imperative to perform a heat load calculation to find out the amount of fuel and heat consumption required to heat the building. These data are required to decide on the purchase of modern heating equipment.

Thermal loads of heat supply systems

The concept of heat load determines the amount of heat that is given off by heating devices installed in a residential building or at an object for other purposes. Before installing the equipment, this calculation is performed in order to avoid unnecessary financial costs and other problems that may arise during the operation of the heating system.

Knowing the main operating parameters of the heat supply design, it is possible to organize the efficient functioning of heating devices. The calculation contributes to the implementation of the tasks facing the heating system, and the compliance of its elements with the norms and requirements prescribed in SNiP.

When the heat load for heating is calculated, even the slightest mistake can lead to big problems, because based on the data obtained, the local housing and communal services office approves limits and other consumption parameters that will become the basis for determining the cost of services.

The total amount of heat load on a modern heating system includes several basic parameters:

• load on the heat supply structure;
• load on the floor heating system, if it is planned to be installed in the house;
• load on the natural and/or forced ventilation system;
• load on the hot water supply system;
• load associated with various technological needs.

Characteristics of the object for calculating thermal loads

The correctly calculated heat load on heating can be determined, provided that absolutely everything, even the slightest nuances, will be taken into account in the calculation process.

The list of details and parameters is quite extensive:

• purpose and type of property. For the calculation, it is important to know which building will be heated - a residential or non-residential building, an apartment (read also: ""). The type of building depends on the load rate determined by the companies supplying heat, and, accordingly, the cost of heat supply;
• architectural features . Take into account the dimensions of such external fences as walls, roofs, flooring and sizes of window, door and balcony openings. The number of storeys of the building, as well as the presence of basements, attics and their inherent characteristics are considered important;
• temperature regime for each room in the house. The temperature is implied for a comfortable stay of people in a living room or area of ​​\u200b\u200bthe administrative building (read: "");
• features of the design of external fences, including the thickness and type of building materials, the presence of a heat-insulating layer and the products used for this;
• purpose of premises. This characteristic is especially important for industrial buildings, in which for each workshop or section it is necessary to create certain conditions regarding the provision of temperature conditions;
• availability of special premises and their features. This applies, for example, to pools, greenhouses, baths, etc.;
• degree of maintenance. Presence/absence of hot water supply, centralized heating, air conditioning system, etc.;
• number of points for the intake of heated coolant. The more of them, the greater the thermal load exerted on the entire heating structure;
• the number of people in the building or living in the house. From given value directly dependent on humidity and temperature, which are taken into account in the formula for calculating the heat load;
• other features of the object. If this is an industrial building, then they can be the number of working days during the calendar year, the number of workers per shift. For a private house, they take into account how many people live in it, how many rooms, bathrooms, etc.

Calculation of heat loads

The heat load of the building is calculated in relation to heating at the stage when a real estate object of any purpose is being designed. This is required in order to prevent unnecessary spending and to choose the right heating equipment.

When making calculations, norms and standards are taken into account, as well as GOSTs, TCH, SNB.

In the course of determining the value of thermal power, a number of factors are taken into account:

The calculation of the thermal loads of the building with a certain degree of margin is necessary in order to prevent unnecessary financial costs in the future.

The need for such actions is most important when arranging heat supply country cottage. In such a property, the installation of additional equipment and other elements of the heating structure will be incredibly expensive.

Features of the calculation of thermal loads

The calculated values ​​of indoor air temperature and humidity and heat transfer coefficients can be found in special literature or in the technical documentation supplied by manufacturers to their products, including heat units.

The standard method for calculating the heat load of a building to ensure its efficient heating includes the consistent determination of the maximum heat flow from heating devices (heating radiators), the maximum heat energy consumption per hour (read: ""). It is also required to know the total consumption of heat power during a certain period of time, for example, during the heating season.

The calculation of thermal loads, which takes into account the surface area of ​​the devices involved in heat exchange, is used for various real estate objects. This calculation option allows you to calculate the parameters of the system as correctly as possible, which will provide efficient heating, as well as to conduct an energy survey of houses and buildings. This is an ideal way to determine the parameters of the on-duty heat supply of an industrial facility, which implies a decrease in temperature during non-working hours.

Methods for calculating thermal loads

To date, the calculation of thermal loads is carried out using several main methods, including:

• calculation of heat losses using aggregated indicators;
• determination of heat transfer of heating and ventilation equipment installed in the building;
• calculation of values ​​taking into account various elements of enclosing structures, as well as additional losses associated with air heating.

Enlarged heat load calculation

An enlarged calculation of the thermal load of a building is used in cases where there is not enough information about the designed object or the required data do not correspond to the actual characteristics.

To carry out such heating calculations, a simple formula is used:

Qmax from.=αxVxq0x(tv-tn.r.) x10-6, where:

• α is a correction factor that takes into account the climatic features of a particular region where the building is being built (used when design temperature different from 30 degrees of frost);
• q0 - specific characteristic of heat supply, which is chosen based on the temperature of the coldest week during the year (the so-called "five days"). See also: "How is the specific heating characteristic of a building calculated - theory and practice";
• V is the outer volume of the building.

Based on the above data, an enlarged calculation of the heat load is performed.

Types of thermal loads for calculations

When making calculations and choosing equipment, different thermal loads are taken into account:

1. Seasonal loads with the following features:

   They are characterized by changes depending on the ambient temperature in the street;
   - the presence of differences in the amount of heat energy consumption in accordance with the climatic features of the region where the house is located;
   - change in the load on the heating system depending on the time of day. Since external fences have heat resistance, this parameter is considered insignificant;
   - heat consumption of the ventilation system depending on the time of day.

2. Permanent thermal loads. In most objects of the heat supply and hot water supply system, they are used throughout the year. For example, in the warm season, the cost of thermal energy in comparison with the winter period is reduced by about 30-35%.
3. dry heat. Represents thermal radiation and convection heat exchange due to other similar devices. This parameter is determined using the dry bulb temperature. It depends on many factors, including windows and doors, ventilation systems, various equipment, air exchange due to the presence of cracks in walls and ceilings. Also take into account the number of people present in the room.
4. Latent heat. It is formed as a result of the process of evaporation and condensation. The temperature is determined using a wet bulb thermometer. In any intended room, the level of humidity is affected by:

   The number of people who are simultaneously in the room;
   - availability of technological or other equipment;
   - flows of air masses penetrating through cracks and cracks in the building envelope.

Thermal Load Controllers

The set of modern boilers for industrial and household purpose includes RTN (thermal load regulators). These devices (see photo) are designed to maintain the power of the heating unit at a certain level and do not allow jumps and dips during their operation.

RTH allow you to save on heating bills, since in most cases there are certain limits and they cannot be exceeded. This is especially true for industrial enterprises. The fact is that for exceeding the limit of thermal loads, penalties should be imposed.

It is quite difficult to make a project on your own and calculate the load on the systems that provide heating, ventilation and air conditioning in a building, so this stage of work is usually trusted to specialists. True, if you wish, you can perform the calculations yourself.

Gav - average hot water consumption.

Comprehensive heat load calculation

In addition to the theoretical solution of issues related to thermal loads, a number of practical activities are carried out during the design. Comprehensive thermal surveys include thermography of all building structures, including ceilings, walls, doors, windows. Thanks to this work, it is possible to identify and fix various factors that affect the heat loss of a house or industrial building.

Thermal imaging diagnostics clearly shows what the real temperature difference will be when a certain amount of heat passes through one "square" of the area of ​​the enclosing structures. Thermography also helps to determine

Thanks to thermal surveys, the most reliable data regarding heat loads and heat losses for a particular building over a certain time period is obtained. Practical measures make it possible to clearly demonstrate what theoretical calculations cannot show - the problem areas of the future structure.

From the foregoing, we can conclude that the calculations of thermal loads on hot water supply, heating and ventilation, similarly hydraulic calculation heating systems are very important and they should certainly be completed before the start of the arrangement of the heat supply system in your own home or at an object for another purpose. When the approach to work is done correctly, the trouble-free operation of the heating structure will be ensured, and at no extra cost.

Video example of calculating the heat load on the heating system of a building: