Regulatory documents for determining the heat load. Self-calculation of the heat load for heating: hourly and annual indicators

In houses that were put into operation in last years, usually these rules are met, so the calculation of the heating power of the equipment is based on standard coefficients. An individual calculation can be carried out at the initiative of the owner of the housing or the communal structure involved in the supply of heat. This happens when spontaneous replacement of heating radiators, windows and other parameters.

In an apartment served by a utility company, the calculation of the heat load can only be carried out upon transfer of the house in order to track the parameters of SNIP in the premises taken on balance. Otherwise, the owner of the apartment does this in order to calculate his heat losses in the cold season and eliminate the shortcomings of insulation - use heat-insulating plaster, glue the insulation, mount penofol on the ceilings and install metal-plastic windows with a five-chamber profile.

The calculation of heat leaks for the public utility in order to open a dispute, as a rule, does not give a result. The reason is that there are heat loss standards. If the house is put into operation, then the requirements are met. At the same time, heating devices comply with the requirements of SNIP. Battery replacement and selection more heat is prohibited, as the radiators are installed according to approved building standards.

Private houses are heated by autonomous systems, which at the same time calculates the load is carried out to comply with the requirements of SNIP, and the correction of heating capacity is carried out in conjunction with work to reduce heat loss.

Calculations can be done manually using a simple formula or a calculator on the site. The program helps to calculate required power heating systems and heat leakage typical of the winter period. Calculations are carried out for a certain thermal zone.

Basic principles

The methodology includes a number of indicators that together allow us to assess the level of insulation of the house, compliance with SNIP standards, as well as the power of the heating boiler. How it works:

An individual or average calculation is carried out for the object. The main purpose of such a survey is to good insulation and small heat leaks in winter, 3 kW can be used. In a building of the same area, but without insulation, at low winter temperatures, the power consumption will be up to 12 kW. Thus, the thermal power and load are estimated not only by area, but also by heat loss.

The main heat loss of a private house:

windows - 10-55%;
walls - 20-25%;
chimney - up to 25%;
roof and ceiling - up to 30%;
low floors - 7-10%;
temperature bridge in the corners - up to 10%

These indicators can vary for better and worse. They are rated according to the types installed windows, thickness of walls and materials, degree of insulation of the ceiling. For example, in poorly insulated buildings, heat loss through walls can reach 45% percent, in which case the expression “we drown the street” is applicable to the heating system. Methodology and
The calculator will help you evaluate the nominal and calculated values.

Specificity of calculations

This technique can still be found under the name "thermal calculation". The simplified formula looks like this:

Qt = V × ∆T × K / 860, where

V is the volume of the room, m³;

∆T is the maximum difference between indoors and outdoors, °С;

K is the estimated heat loss coefficient;

860 is the conversion factor in kWh.

The heat loss coefficient K depends on building structure, wall thickness and thermal conductivity. For simplified calculations, you can use the following parameters:

K \u003d 3.0-4.0 - without thermal insulation (non-insulated frame or metal structure);
K \u003d 2.0-2.9 - low thermal insulation (laying in one brick);
K \u003d 1.0-1.9 - average thermal insulation ( brickwork in two bricks);
K \u003d 0.6-0.9 - good thermal insulation according to the standard.

These coefficients are averaged and do not allow estimating heat loss and heat load on the room, so we recommend using the online calculator.

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Order of the Ministry of Regional Development of the Russian Federation of December 28, 2009 N 610
"On Approval of the Rules for Establishing and Changing (Revising) Thermal Loads"

In accordance with paragraph 2 of the Government Decree Russian Federation dated February 14, 2009 N 121 "On Amendments to the Decree of the Government of the Russian Federation dated February 26, 2004 N 109" (Sobraniye Zakonodatelstva Rossiyskoy Federatsii, 2009, N 8, Art. 982) I order:

1. Approve the agreements agreed with the Ministry of Economic Development of the Russian Federation, the Ministry of Energy of the Russian Federation and Federal Service on tariffs Rules for establishing and changing (revising) heat loads.

2. To impose control over the execution of this order on the Deputy Minister of Regional Development of the Russian Federation S.I. Kruglik.

And about. Minister

V.A. Tokarev

The Government of the Russian Federation has identified two options for establishing regulated tariffs (prices) for thermal energy(capacity) - one-rate and two-rate tariffs. The first includes the full cost of 1 gigacalorie of supplied thermal energy. The second is the rate of payment for consumed resources based on the fee for 1 gigacalorie of energy and the rate of payment for capacity based on the fee for 1 gigacalorie per hour of heat load (set in the energy supply contract).

Rules for establishing and changing thermal loads have been developed. They are used when calculating the cost of using capacity under an energy supply agreement.

The values of thermal loads are fixed in energy supply contracts. To do this, consumers submit applications to the energy supply organization.

An energy supplying organization that has prepared proposals for establishing a two-part tariff is obliged to notify all consumers whose contracts do not contain information about heat loads of the need to submit applications within 45 days.

If applications are not sent within this period, the power supply organization has the right to independently determine the heat loads based on the available data.

Thermal loads are set for each facility separately by type of heat consumption and coolant.

Thermal loads can be changed due to organizational and technical measures. Among them are the overhaul of the building, the reconstruction of internal engineering communications, constructive changes in thermal protection. To revise heat loads, consumers must submit applications no later than March 1 of the current year.

Changes in heat load values shall take effect on January 1 of the year following the one in which applications are submitted.

The power supply organization has the right to install equipment to limit the power consumption of thermal power ("settings").

Order of the Ministry of Regional Development of the Russian Federation of December 28, 2009 N 610 "On Approval of the Rules for Establishing and Changing (Revising) Thermal Loads"

Registration N 16604

This Order shall enter into force 10 days after the date of its official publication.

q - specific heating characteristic building, kcal / mh ° С is taken from the reference book, depending on the external volume of the building.

a is a correction factor that takes into account climatic conditions district, for Moscow, a = 1.08.

V - the outer volume of the building, m is determined by construction data.

t - the average air temperature inside the room, ° C is taken depending on the type of building.

t - design temperature of outdoor air for heating, °С for Moscow t= -28 °С.

Source: http://vunivere.ru/work8363

Q yh is made up of the thermal loads of devices serviced by water flowing through the site:

(3.1)

For the section of the supply heat pipe thermal load expresses the heat reserve in the flowing hot water, intended for subsequent (on the further path of water) heat transfer to the premises. For the section of the return heat pipeline - the loss of heat by the flowing chilled water during heat transfer to the premises (on the previous water path). The thermal load of the site is designed to determine the flow of water in the site in the process of hydraulic calculation.

Water consumption on the site G uch at the calculated difference in water temperature in the system t g - t x, taking into account additional heat supply to the premises

where Q ych is the thermal load of the section, found by formula (3.1);

β 1 β 2 - correction factors that take into account additional heat supply to the premises;

c - specific mass heat capacity of water, equal to 4.187 kJ / (kg ° C).

To obtain the water flow in the area in kg / h, the heat load in W should be expressed in kJ / h, i.e. multiply by (3600/1000)=3.6.

as a whole is equal to the sum of heat loads of all heating devices (heat losses of premises). According to the total heat demand for heating the building, the water flow in the heating system is determined.

Hydraulic calculation is associated with the thermal calculation of heating appliances and pipes. Multiple repetition of calculations is required to identify the actual flow and temperature of water, required area appliances. When calculating manually, first perform a hydraulic calculation of the system, taking the average values of the local resistance coefficient (LFR) of the devices, then - the thermal calculation of pipes and devices.

If convectors are used in the system, the design of which includes pipes Dy15 and Dy20, then for a more accurate calculation, the length of these pipes is preliminarily determined, and after hydraulic calculation, taking into account the pressure losses in the pipes of the devices, having specified the flow rate and temperature of the water, they make adjustments to the dimensions of the devices.

Source: http://teplodoma.com.ua/1/gidravliheskiy_rashet/str_19.html

In this section, you will be able to get acquainted with the issues related to the calculation of heat losses and heat loads of the building in as much detail as possible.

The construction of heated buildings without heat loss calculation is prohibited!*)

And although most are still building at random, on the advice of a neighbor or godfather. It is right and clear to start at the stage of developing a working draft for construction. How it's done?

The architect (or the developer himself) provides us with a list of "available" or "priority" materials for arranging walls, roofs, bases, which windows, doors are planned.

Already at the design stage of a house or building, as well as for the selection of heating, ventilation, air conditioning systems, it is necessary to know the heat losses of the building.

Calculation of heat loss for ventilation we often use in our practice to calculate economic feasibility modernization and automation of the ventilation / air conditioning system, as calculation of heat losses for ventilation gives a clear idea of the benefits and payback period of funds invested in energy-saving measures (automation, use of recuperation, insulation of air ducts, frequency controllers).

Calculation of building heat losses

This is the basis for the competent selection of the power of heating equipment (boiler, boiler) and heating appliances

The main heat losses of a building usually occur in the roof, walls, windows and floors. A sufficiently large part of the heat leaves the premises through the ventilation system.

Rice. 1 Building heat loss

The main factors affecting heat loss in a building are the temperature difference between indoors and outdoors (the greater the difference, the greater the body loss) and the thermal insulation properties of building envelopes (foundation, walls, ceilings, windows, roofing).

Fig. 2 Thermal imaging survey of building heat losses

Enclosing materials prevent the penetration of heat from the premises to the outside in winter and the penetration of heat into the premises in summer, because the selected materials must have certain thermal insulation properties, which are denoted by a value called - heat transfer resistance.

The resulting value will show what the real temperature difference will be when a certain amount of heat passes through 1m² of a particular building envelope, as well as how much heat will leave after 1m² at a certain temperature difference.

#image.jpgHow heat loss is calculated

When calculating the heat loss of a building, we will be mainly interested in all external enclosing structures and the location of internal partitions.

To calculate heat losses along the roof, it is also necessary to take into account the shape of the roof and the presence of an air gap. There are also some nuances in the thermal calculation of the floor of the room.

To obtain the most accurate value of the heat loss of a building, it is necessary to take into account absolutely all enclosing surfaces (foundation, floors, walls, roof), their constituent materials and the thickness of each layer, as well as the position of the building relative to the cardinal points and climatic conditions in the region.

To order the calculation of heat losses you need fill out our questionnaire and we will send our commercial offer to the specified postal address as soon as possible (no more than 2 working days).

Scope of work on the calculation of thermal loads of the building

The main composition of the documentation for the calculation of the thermal load of the building:

building heat loss calculation
calculation of heat losses for ventilation and infiltration
permits
summary table of thermal loads

The cost of calculating the thermal loads of the building

The cost of services for calculating the thermal loads of a building does not have a single price, the price for the calculation depends on many factors:

heated area;
availability of project documentation;
architectural complexity of the object;
composition of enclosing structures;
the number of heat consumers;
the diversity of the purpose of the premises, etc.

Finding out the exact cost and ordering a service for calculating the heat load of a building is not difficult, for this you just need to send us a email(form) floor plan of the building, fill in a small questionnaire and in 1 working day you will receive our commercial offer to the mailbox indicated by you.

#image.jpgExamples of the cost of calculating thermal loads

Thermal calculations for a private house

Documentation set:

- calculation of heat losses (room by room, floor by floor, infiltration, total)

- calculation of heat load for heating hot water(DHW)

- calculation for heating air from the street for ventilation

A package of thermal documents will cost in this case - 1600 UAH

For such calculations bonus You get:

Recommendations for insulation and elimination of cold bridges

Power selection of the main equipment

_____________________________________________________________________________________

Sports complex - detached 4 storey building standard building, with a total area of 2100 sq.m. with a large gym, heated supply and exhaust ventilation system, radiator heating, complete set documentation - 4200.00 UAH

_____________________________________________________________________________________

Shop - a premise built into a residential building on the 1st floor, with a total area of 240 sq.m. of which 65 sq.m. warehouses, without cellar, radiator heating, heated supply and exhaust ventilation with recovery 2600.00 UAH

______________________________________________________________________________________

Terms of performance of work on the calculation of thermal loads

The term for performing work on the calculation of the thermal loads of the building mainly depends on the following components:

total heated area of premises or building
architectural complexity of the object
complexity or multi-layered enclosing structures
number of heat consumers: heating, ventilation, hot water, other
multifunctionality of premises (warehouse, offices, trading floor, residential, etc.)
organization of a heat energy commercial metering unit
completeness of the availability of documentation (project of heating, ventilation, executive schemes for heating, ventilation, etc.)
diversity of use of building envelope materials in construction
complexity of the ventilation system (recuperation, automatic control system, zone temperature control)

In most cases, for a building with a total area of not more than 2000 sq.m. The term for calculating the thermal loads of a building is 5 to 21 working days depending on the above characteristics of the building, provided documentation and engineering systems.

Coordination of calculation of heat loads in heat networks

After completing all the work on the calculation of thermal loads and collecting all required documents we are approaching the final, but difficult issue of coordinating the calculation of heat loads in urban heating networks. This process is a “classic” example of communication with the state structure, notable for a lot of interesting innovations, clarifications, views, interests of a subscriber (client) or a representative of a contracting organization (which has undertaken to coordinate the calculation of heat loads in heating networks) with representatives of urban heating networks. In general, the process is often difficult, but surmountable.

The list of documents to be submitted for approval looks something like this:

Application (written directly in thermal networks);
Calculation of thermal loads (in in full);
License, list of licensed works and services of the contractor performing the calculations;
Registration certificate for the building or premises;
The right establishing the documentation for the ownership of the object, etc.

Usually for term for approval of the calculation of thermal loads accepted - 2 weeks (14 working days) subject to the submission of documentation in full and in the required form.

Services for calculating the thermal loads of the building and related tasks

When concluding or re-executing an agreement on the supply of heat from city heating networks or designing and installing a commercial heat metering unit, heating network notify the owner of the building (premises) of the need to:

receive specifications(THAT);
provide a calculation of the thermal load of the building for approval;
project for the heating system;
project for the ventilation system;
and etc.

We offer our services in carrying out the necessary calculations, designing heating systems, ventilation and subsequent approvals in urban heating networks and other regulatory authorities.

You can order both a separate document, project or calculation, as well as execution of all necessary documents on a turnkey basis from any stage.

Discuss the topic and leave feedback: "CALCULATION OF HEAT LOSSES AND LOADS" on FORUM #image.jpg

We will be glad to continue cooperation with you by offering:

Supply of equipment and materials at wholesale prices

Design work

Assembly / installation / commissioning

Further maintenance and provision of services at reduced prices (for regular customers)

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 carried out in order to avoid unnecessary financial expenses 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 department approves limits and other consumption parameters that will become the basis for determining the cost of services.

The total value of the heat load on the 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 system by natural and/or forced ventilation;
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 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 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, installation additional equipment and other elements of the heating structure will be incredibly expensive.

Features of the calculation of thermal loads

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

The standard methodology for calculating the heat load of a building to ensure its efficient heating includes the consistent determination maximum flow heat from heating appliances (heating radiators), the maximum consumption of thermal energy 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 most correctly calculate the parameters of the system, 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 the 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 (it is used when the design temperature differs from 30 degrees below zero);
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:

Seasonal loads having 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.
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 winter period are reduced somewhere by 30-35%.
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.
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 independently make a project and calculate the load on systems that provide heating, ventilation and air conditioning in a building, therefore this stage works are usually trusted by specialists. True, if you wish, you can perform the calculations yourself.

Gav - average hot water consumption.

Comprehensive heat load calculation

Apart from theoretical solution issues related to thermal loads, a number of practical measures are taken 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 period of time is obtained. Practical activities allow you to clearly demonstrate what theoretical calculations cannot show - problem areas future building.

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 own house or at another facility. 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:

How to optimize heating costs? This task can be solved only by an integrated approach that takes into account all the parameters of the system, the building and the climatic features of the region. At the same time, the most important component is the heat load on heating: the calculation of hourly and annual indicators are included in the system for calculating the efficiency of the system.

Why do you need to know this parameter

What is the calculation of the heat load for heating? It determines the optimal amount of thermal energy for each room and building as a whole. Variables are the power of heating equipment - boiler, radiators and pipelines. The heat losses of the house are also taken into account.

Ideally, the thermal power of the heating system should compensate for all heat losses and at the same time maintain a comfortable temperature level. Therefore, before calculating the annual heating load, you need to determine the main factors affecting it:

Characteristics of the structural elements of the house. External walls, windows, doors, ventilation system affect the level of heat losses;
House dimensions. It is logical to assume that the larger the room, the more intensively the heating system should work. An important factor in this case is not only the total volume of each room, but also the area of \u200b\u200bthe outer walls and window structures;
climate in the region. With relatively small drops in outdoor temperature, a small amount of energy is needed to compensate for heat losses. Those. the maximum hourly heating load directly depends on the degree of temperature decrease in a certain period of time and the average annual value for heating season.

Considering these factors, the optimal thermal mode of operation of the heating system is compiled. Summarizing all of the above, we can say that determining the heat load for heating is necessary to reduce energy consumption and maintain the optimal level of heating in the premises of the house.

To calculate the optimal heating load according to aggregated indicators, you need to know the exact volume of the building. It is important to remember that this technique was developed for large structures, so the calculation error will be large.

Choice of calculation method

Before calculating the heating load using aggregated indicators or with higher accuracy, it is necessary to find out the recommended temperature conditions for a residential building.

During the calculation of the heating characteristics, one must be guided by the norms of SanPiN 2.1.2.2645-10. Based on the data in the table, in each room of the house it is necessary to provide optimal temperature regime heating work.

The methods by which the calculation of the hourly heating load is carried out can have a different degree of accuracy. In some cases, it is recommended to use fairly complex calculations, as a result of which the error will be minimal. If the optimization of energy costs is not a priority when designing heating, less accurate schemes can be used.

When calculating the hourly heating load, it is necessary to take into account the daily change in street temperature. To improve the accuracy of the calculation, you need to know specifications building.

Easy Ways to Calculate Heat Load

Any calculation of the heat load is needed to optimize the parameters of the heating system or improve thermal insulation characteristics Houses. After its implementation, certain methods of regulating the heating load of heating are selected. Consider non-labor-intensive methods for calculating this parameter of the heating system.

The dependence of heating power on the area

For home with standard sizes rooms, ceiling heights and good thermal insulation, you can apply the known ratio of the area of \u200b\u200bthe room to the required heat output. In this case, 1 kW of heat will be required per 10 m². To the result obtained, you need to apply a correction factor depending on the climatic zone.

Let's assume that the house is located in the Moscow region. Its total area is 150 m². In this case, the hourly heat load on heating will be equal to:

15*1=15 kWh

The main disadvantage of this method is the large error. The calculation does not take into account changes in weather factors, as well as building features - heat transfer resistance of walls and windows. Therefore, it is not recommended to use it in practice.

Enlarged calculation of the thermal load of the building

The enlarged calculation of the heating load is characterized by more accurate results. Initially, it was used to pre-calculate this parameter when it was impossible to determine the exact characteristics of the building. General formula to determine the heat load on heating is presented below:

Where q°- specific thermal characteristic of the structure. The values must be taken from the corresponding table, but- correction factor, which was mentioned above, Vn- external volume of the building, m³, Tvn And Tnro– temperature values inside the house and outside.

Suppose we need to calculate the maximum hourly load for heating in a house with a volume on the outer walls of 480 m³ (area 160 m², two-storey house). In this case, the thermal characteristic will be equal to 0.49 W / m³ * C. Correction factor a = 1 (for the Moscow region). Optimum temperature inside the dwelling (Tvn) should be + 22 ° С. The outside temperature will be -15°C. We use the formula to calculate the hourly heating load:

Q=0.49*1*480(22+15)= 9.408 kW

Compared to the previous calculation, the resulting value is less. However, she takes into account important factors- the temperature inside the room, on the street, the total volume of the building. Similar calculations can be made for each room. The method of calculating the load on heating according to aggregated indicators makes it possible to determine the optimal power for each radiator in a single room. For a more accurate calculation, you need to know the average temperature values \u200b\u200bfor a particular region.

This calculation method can be used to calculate the hourly heat load for heating. But the results obtained will not give the optimally accurate value of the heat loss of the building.

Accurate heat load calculations

But still, this calculation of the optimal heat load on heating does not give the required calculation accuracy. It does not take into account the most important parameter - the characteristics of the building. The main one is the heat transfer resistance material of manufacture individual elements houses - walls, windows, ceiling and floor. They determine the degree of conservation of thermal energy received from the heat carrier of the heating system.

What is heat transfer resistance? R)? This is the reciprocal of the thermal conductivity ( λ ) - the ability of the material structure to transfer thermal energy. Those. the higher the thermal conductivity value, the higher the heat loss. This value cannot be used to calculate the annual heating load, since it does not take into account the thickness of the material ( d). Therefore, experts use the heat transfer resistance parameter, which is calculated by the following formula:

Calculation for walls and windows

There are normalized values of heat transfer resistance of walls, which directly depend on the region where the house is located.

In contrast to the enlarged calculation of the heating load, you first need to calculate the heat transfer resistance for external walls, windows, the floor of the first floor and the attic. Let's take as a basis following characteristics Houses:

Wall area - 280 m². It includes windows 40 m²;
Wall material - solid brick (λ=0.56). The thickness of the outer walls 0.36 m. Based on this, we calculate the TV transmission resistance - R=0.36/0.56= 0.64 m²*S/W;
To improve the thermal insulation properties, an external insulation was installed - expanded polystyrene with a thickness of 100 mm. For him λ=0.036. Respectively R \u003d 0.1 / 0.036 \u003d 2.72 m² * C / W;
General value R for exterior walls 0,64+2,72= 3,36 which is a very good indicator of the thermal insulation of the house;
Heat transfer resistance of windows - 0.75 m²*S/W(double glazing with argon filling).

In fact, heat losses through the walls will be:

(1/3.36)*240+(1/0.75)*40= 124 W at 1°C temperature difference

We take the temperature indicators the same as for the enlarged calculation of the heating load + 22 ° С indoors and -15 ° С outdoors. Further calculation must be done according to the following formula:

124*(22+15)= 4.96 kWh

Ventilation calculation

Then you need to calculate the losses through ventilation. The total air volume in the building is 480 m³. At the same time, its density is approximately equal to 1.24 kg / m³. Those. its mass is 595 kg. On average, the air is renewed five times per day (24 hours). In this case, to calculate the maximum hourly load for heating, you need to calculate the heat loss for ventilation:

(480*40*5)/24= 4000 kJ or 1.11 kWh

Summing up all the obtained indicators, you can find the total heat loss of the house:

4.96+1.11=6.07 kWh

In this way, the exact maximum heating load is determined. The resulting value directly depends on the temperature outside. Therefore, to calculate the annual load on the heating system, it is necessary to take into account the change weather conditions. If the average temperature during the heating season is -7°C, then the total heating load will be equal to:

(124*(22+7)+((480*(22+7)*5)/24))/3600)*24*150(heating season days)=15843 kW

By changing the temperature values, you can make an accurate calculation of the heat load for any heating system.

To the results obtained, it is necessary to add the value of heat losses through the roof and floor. This can be done with a correction factor of 1.2 - 6.07 * 1.2 \u003d 7.3 kW / h.

The resulting value indicates the actual cost of the energy carrier during the operation of the system. There are several ways to regulate the heating load of heating. The most effective of them is to reduce the temperature in rooms where there is no constant presence of residents. This can be done with thermostats and installed sensors temperature. But at the same time, a two-pipe heating system must be installed in the building.

To calculate exact value heat losses, you can use the specialized program Valtec. The video shows an example of working with it.

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