An indicator of thermal energy consumption for heating and ventilation of a residential or public building at the stage of development of project documentation is the specific characteristic of thermal energy consumption for heating and ventilation of a building numerically equal to the consumption of thermal energy per 1 m 3 of heated volume of the building per unit time with a temperature difference of 1° WITH, , W/(m 3 0 C). Estimated value specific characteristics thermal energy consumption for heating and ventilation of the building,
, W/(m 3 · 0 C), is determined by a method taking into account the climatic conditions of the construction area, the selected space-planning solutions, the orientation of the building, the heat-insulating properties of the building envelope, the adopted building ventilation system, as well as the use of energy-saving technologies. The calculated value of the specific characteristic of thermal energy consumption for heating and ventilation of the building must be less than or equal to the standardized value, according to
, W/(m 3 0 C):

≤
(7.1)

Where
- standardized specific characteristic of thermal energy consumption for heating and ventilation of buildings, W/(m 3 0 C), determined for various types residential and public buildings according to table 7.1 or 7.2.

Table 7.1

, W/(m 3 0 C)

Building area, m2	With number of floors
1000 or more

Notes:

At intermediate values ​​of the heated area of ​​the building in the range of 50-1000m 2 values
must be determined by linear interpolation.

Table 7.2

Standardized (basic) specific flow rate characteristic

thermal energy for heating and ventilation

low-rise residential single-apartment buildings,
, W/(m 3 0 C)

Building type	Number of floors of the building
1 Residential apartment buildings, hotels, dormitories
2 Public, except those listed in lines 3-6
3 Clinics and medical institutions, boarding houses
4 Preschool institutions, hospices
5 Service, cultural and leisure activities, technology parks, warehouses
6 Administrative purposes (offices)

Notes:

For regions with a GSOP value of 8000 0 C day or more, standardized
should be reduced by 5%.

To assess the energy demand for heating and ventilation achieved in a building design or in an operating building, the following energy saving classes have been established (Table 7.3) in % deviation of the calculated specific characteristics of thermal energy consumption for heating and ventilation of the building from the standardized (base) value.

Designing buildings with energy saving class “D, E” is not allowed. Classes “A, B, C” are established for newly constructed and reconstructed buildings at the stage of development of project documentation. Subsequently, during operation, the energy efficiency class of the building must be clarified during an energy survey. In order to increase the share of buildings with classes “A, B”, the constituent entities of the Russian Federation must apply economic incentive measures to both participants in the construction process and operating organizations.

Table 7.3

Energy saving classes of residential and public buildings

Designation	Name	The magnitude of the deviation of the calculated (actual) value of the specific characteristic of thermal energy consumption for heating and ventilation of the building from the standardized value, %
When designing and operating new and reconstructed buildings
	Very tall		Economic stimulation
		From - 50 to - 60 inclusive
		From - 40 to - 50 inclusive
		From - 30 to - 40 inclusive	Economic stimulation
		From - 15 to - 30 inclusive
	Normal	From - 5 to - 15 inclusive	Events not are being developed
		From + 5 to - 5 inclusive
		From + 15 to + 5 inclusive
	Reduced	From + 15.1 to + 50 inclusive	Reconstruction with appropriate economic justification
			Reconstruction with appropriate economic justification, or demolition

Estimated specific characteristics of thermal energy consumption for heating and ventilation of the building,
, W/(m 3 0 C), should be determined by the formula

k about - specific heat-protective characteristic of the building, W/(m 3 0 C), is determined as follows

, (7.3)

Where - actual total heat transfer resistance for all layers of the fence (m 2 С)/W;

- area of ​​the corresponding fragment of the building’s heat-protective shell, m2;

V from - heated volume of the building, equal to the volume limited by the internal surfaces of the external fences of the buildings, m 3;

- coefficient that takes into account the difference between the internal or external temperature of the structure from those adopted in the GSOP calculation, =1.

k vent - specific ventilation characteristics of the building, W/(m 3 ·C);

k household - specific characteristic of household heat emissions of a building, W/(m 3 ·C);

k rad - specific characteristic of heat input into the building from solar radiation, W/(m 3 0 C);

ξ - coefficient taking into account the reduction in heat consumption of residential buildings, ξ =0.1;

β - coefficient taking into account additional heat consumption heating systems, β h = 1,05;

ν is the coefficient of reduction of heat input due to the thermal inertia of enclosing structures; recommended values ​​are determined by the formula ν = 0.7+0.000025*(GSOP-1000);

The specific ventilation characteristic of a building, k vent, W/(m 3 0 C), should be determined by the formula

where c is the specific heat capacity of air, equal to 1 kJ/(kg °C);

β v- coefficient of air volume reduction in the building, β v = 0,85;

- average density of supply air during the heating period, kg/m3

=353/, (7.5)

t from - average temperature heating season, С, to 6, table. 3.1, (see appendix 6).

n in - the average air exchange rate of a public building during the heating period, h -1, for public buildings, according to , the average value of n in = 2 is accepted;

k e f - recuperator efficiency coefficient, k e f =0.6.

The specific characteristics of the domestic heat emission of a building, k household, W/(m 3 C), should be determined by the formula

, (7.6)

where q life is the amount of household heat generation per 1 m 2 of residential premises area (Azh) or the estimated area of ​​a public building (Ar), W/m2, accepted for:

a) residential buildings with an estimated occupancy of apartments of less than 20 m2 of total area per person q life = 17 W/m2;

b) residential buildings with an estimated occupancy of apartments of 45 m2 of total area or more per person q life = 10 W/m2;

c) other residential buildings - depending on the estimated occupancy of apartments by interpolation of the value q life between 17 and 10 W/m 2;

d) for public and administrative buildings, household heat emissions are taken into account according to the estimated number of people (90 W/person) in the building, lighting (according to installed power) and office equipment (10 W/m2) taking into account working hours per week;

t in, t from - the same as in formulas (2.1, 2.2);

Аж - for residential buildings - the area of ​​residential premises (Аж), which include bedrooms, children's rooms, living rooms, offices, libraries, dining rooms, kitchen-dining rooms; for public and administrative buildings - the estimated area (A p), determined in accordance with SP 117.13330 as the sum of the areas of all premises, with the exception of corridors, vestibules, passages, staircases, elevator shafts, internal open stairs and ramps, as well as premises intended to accommodate engineering equipment and networks, m 2.

The specific characteristic of heat input into a building from solar radiation, krad, W/(m 3 °C), should be determined by the formula

, (7.7)

Where
- heat gain through windows and skylights from solar radiation during the heating season, MJ/year, for four facades of buildings oriented in four directions, determined by the formula

- coefficients of relative penetration of solar radiation for light-transmitting fillings of windows and skylights, respectively, taken according to the passport data of the corresponding light-transmitting products; in the absence of data should be taken should be taken according to table (2.8); skylights with an angle of inclination of the fillings to the horizon of 45° or more should be considered as vertical windows, with an inclination angle of less than 45° - as skylights;

- coefficients taking into account the shading of the light opening of windows and skylights, respectively, by opaque filling elements, adopted according to design data; in the absence of data, it should be taken according to table (2.8).

- area of ​​light openings of the building facades (the blind part of the balcony doors is excluded), respectively oriented in four directions, m2;

- area of ​​light openings of skylights of the building, m;

- the average value of total solar radiation during the heating period (direct plus scattered) on vertical surfaces under actual cloudy conditions, respectively oriented along the four facades of the building, MJ/m 2, determined by app. 8;

- the average value of the total solar radiation (direct plus scattered) on a horizontal surface during the heating period under actual cloud conditions, MJ/m 2, determined by adj. 8.

V from - the same as in formula (7.3).

GSOP – the same as in formula (2.2).

Calculation of specific characteristics of thermal energy consumption

for heating and ventilation of the building

Initial data

We will calculate the specific characteristics of thermal energy consumption for heating and ventilation of a building using the example of a two-story individual residential building with a total area of ​​248.5 m2. Values ​​of the quantities required for the calculation: tв = 20 С; t op = -4.1С;
= 3.28(m 2 С)/W;
=4.73 (m 2 С)/W;
=4.84 (m 2 С)/W; =0.74 (m 2 С)/W;
=0.55(m 2 С)/W;
m 2;
m 2;
m 2;
m 2;
m 2;
m 2;
m 3;
W/m2;
0,7;
0;
0,5;
0;
7.425 m2;
4.8 m2;
6.6 m2;
12.375 m2;
m 2;
695 MJ/(m2 year);
1032 MJ/(m 2 year);
1032 MJ/(m 2 year); =1671 MJ/(m 2 year);
= =1331 MJ/(m 2 year).

Calculation procedure

1. Calculate the specific heat-protective characteristic of the building, W/(m 3 0 C), according to formula (7.3) determined as follows

W/(m 3 0 C),

2. Using formula (2.2), the degree-days of the heating period are calculated

D= (20 + 4.1)200 = 4820 Cday.

3. Find the coefficient of reduction of heat input due to the thermal inertia of the enclosing structures; recommended values ​​are determined by the formula

ν = 0.7+0.000025*(4820-1000)=0.7955.

4. Find the average density of supply air during the heating period, kg/m3, using formula (7.5)

=353/=1.313 kg/m3.

5. We calculate the specific ventilation characteristics of the building using formula (7.4), W/(m 3 0 C)

W/(m 3 0 C)

6. I determine the specific characteristics of the domestic heat release of the building, W/(m 3 C), according to formula (7.6)

W/(m 3 C),

7. Using formula (7.8), heat input through windows and skylights from solar radiation during the heating period, MJ/year, is calculated for four facades of buildings oriented in four directions

8. Using formula (7.7), the specific characteristic of heat input into the building from solar radiation is determined, W/(m 3 °C)

W/(m 3 °С),

9. Determine the calculated specific characteristic of thermal energy consumption for heating and ventilation of the building, W/(m 3 0 C), according to formula (7.2)

W/(m 3 0 C)

10. Compare the obtained value of the calculated specific characteristic of thermal energy consumption for heating and ventilation of the building with the standardized (base) one,
, W/(m 3 · 0 C), according to tables 7.1 and 7.2.

0.4 W/(m 3 0 C)
=0.435 W/(m 3 0 C)

≤

The calculated value of the specific characteristics of thermal energy consumption for heating and ventilation of the building must be less than the standardized value.

To assess the energy demand for heating and ventilation achieved in a building design or in an operating building, the energy saving class of the designed residential building is determined by the percentage deviation of the calculated specific characteristics of thermal energy consumption for heating and ventilation of the building from the standardized (base) value.

Conclusion: The designed building belongs to the “C+ Normal” energy saving class, which is established for newly constructed and reconstructed buildings at the stage of development of design documentation. The development of additional measures to improve the energy efficiency class of the building is not required. Subsequently, during operation, the energy efficiency class of the building must be clarified during an energy survey.

Test questions for section 7:

1. What value is the main indicator of thermal energy consumption for heating and ventilation of a residential or public building at the stage of developing project documentation? What does it depend on?

2. What classes of energy efficiency of residential and public buildings exist?

3. What energy saving classes are established for newly constructed and reconstructed buildings at the stage of developing project documentation?

4. Designing buildings with which energy saving class is not allowed?

CONCLUSION

Problems of saving energy resources are especially important in the current period of development of our country. The cost of fuel and thermal energy is rising, and this trend is predicted for the future; At the same time, energy consumption is constantly and rapidly increasing. The energy intensity of national income in our country is several times higher than in developed countries.

In this regard, the importance of identifying reserves for reducing energy costs is obvious. One of the areas for saving energy resources is the implementation of energy-saving measures during the operation of heat supply, heating, ventilation and air conditioning (HVAC) systems. One solution to this problem is to reduce heat loss from buildings through building envelopes, i.e. reduction of thermal loads on DVT systems.

The importance of solving this problem is especially great in urban engineering, where about 35% of all extracted solid and gaseous fuel is spent on heat supply of residential and public buildings alone.

In recent years, an imbalance in the development of sub-sectors of urban construction has become sharply evident in cities: technical backwardness of engineering infrastructure, uneven development of individual systems and their elements, a departmental approach to the use of natural and produced resources, which leads to their irrational use and sometimes to the need to attract appropriate resources from other regions.

The demand of cities for fuel and energy resources and the provision of engineering services is growing, which directly affects the increase in morbidity among the population and leads to the destruction of the forest belt of cities.

The use of modern thermal insulation materials with a high value of heat transfer resistance will lead to a significant reduction in energy costs, the result will be a significant economic effect in the operation of DVT systems through a reduction in fuel costs and, accordingly, an improvement in the environmental situation of the region, which will reduce the cost of medical care for the population.

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21. TSN 23-319-2000. Krasnodar region. Energy efficiency of residential and public buildings [Text]. – M.: GosstroyRussii, 2000.

22. TSN 23-310-2000. Belgorod region. Energy efficiency of residential and public buildings [Text]. – M.: GosstroyRussii, 2000.

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27. TSN 23-336-2002. Kemerovo region. Energy efficiency of residential and public buildings. [Text]. – M.: GosstroyRussii, 2002.

28. TSN 23-320-2000. Chelyabinsk region. Energy efficiency of residential and public buildings. [Text]. – M.: GosstroyRussii, 2002.

29. TSN 23-301-2002. Sverdlovsk region. Energy efficiency of residential and public buildings. [Text]. – M.: GosstroyRussii, 2002.

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31. TSN 23-312-2000. Vladimir region. Thermal protection of residential and public buildings. [Text]. – M.: GosstroyRussii, 2000.

32. TSN 23-306-99. Sakhalin region. Thermal protection and energy consumption of residential and public buildings. [Text]. – M.: GosstroyRussii, 1999.

33. TSN 23-316-2000. Tomsk region. Thermal protection of residential and public buildings. [Text]. – M.: GosstroyRussii, 2000.

34. TSN 23-317-2000. Novosibirsk region. Energy saving in residential and public buildings. [Text]. – M.: GosstroyRussii, 2002.

35. TSN 23-318-2000. Republic of Bashkortostan. Thermal protection of buildings. [Text]. – M.: GosstroyRussii, 2000.

36. TSN 23-321-2000. Astrakhan region. Energy efficiency of residential and public buildings. [Text]. – M.: GosstroyRussii, 2000.

37. TSN 23-322-2001. Kostroma region. Energy efficiency of residential and public buildings. [Text]. – M.: GosstroyRussii, 2001.

38. TSN 23-324-2001. Komi Republic. Energy-saving thermal protection of residential and public buildings. [Text]. – M.: GosstroyRussii, 2001.

39. TSN 23-329-2002. Oryol Region. Energy efficiency of residential and public buildings. [Text]. – M.: GosstroyRussii, 2002.

40. TSN 23-333-2002. Nenets Autonomous Okrug. Energy consumption and thermal protection of residential and public buildings. [Text]. – M.: GosstroyRussii, 2002.

41. TSN 23-338-2002. Omsk region. Energy saving in civil buildings. [Text]. – M.: GosstroyRussii, 2002.

42. TSN 23-341-2002. Ryazan Oblast. Energy efficiency of residential and public buildings. [Text]. – M.: GosstroyRussii, 2002.

43. TSN 23-343-2002. Saha Republic. Thermal protection and energy consumption of residential and public buildings. [Text]. – M.: GosstroyRussii, 2002.

44. TSN 23-345-2003. Udmurt republic. Energy saving in buildings. [Text]. – M.: GosstroyRussii, 2003.

45. TSN 23-348-2003. Pskov region. Energy efficiency of residential and public buildings. [Text]. – M.: GosstroyRussii, 2003.

46. ​​TSN 23-305-99. Saratov region. Energy efficiency of residential and public buildings. [Text]. – M.: GosstroyRussii, 1999.

47. TSN 23-355-2004. Kirov region. Energy efficiency of residential and public buildings. [Text]. – M.: GosstroyRussii, 2004.

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50. TSN 23-314-2000. Kaliningrad region. Standards for energy-saving thermal protection of residential and public buildings. [Text]. – M.: GosstroyRussii, 2000.

51. TSN 23-350-2004. Vologda Region. Energy efficiency of residential and public buildings. [Text]. – M.: GosstroyRussii, 2004.

52. TSN 23-358-2004. Orenburg region. Energy efficiency of residential and public buildings. [Text]. – M.: GosstroyRussii, 2004.

53. TSN 23-331-2002. Chita region. Energy efficiency of residential and public buildings. [Text]. – M.: GosstroyRussii, 2002.

Thermal balance of the room.

Purpose – comfortable conditions or technological process.

The heat generated by people is evaporation from the surface of the skin and lungs, convection and radiation. The intensity of radiation by convection is determined by the temperature and mobility of the surrounding air, radiation - by the temperature of the surfaces of the fences. The temperature conditions depend on: thermal power CO, location of heaters, thermophysics. properties of external and internal fences, intensity of other sources of income (lighting, household appliances) and heat loss. In winter - heat loss through external fences, heating of outside air penetrating through leaks in fences, cold objects, ventilation.

Technological processes can be associated with the evaporation of liquids and other processes accompanied by the consumption of heat and the release of heat (moisture condensation, chemical reactions, etc.).

Taking into account all of the above - the heat balance of the premises of the building, determining the deficit or excess of heat. The period of the technological cycle with the least heat release is taken into account (possible maximum heat release is taken into account when calculating ventilation), for households - with the greatest heat loss. The heat balance is compiled for stationary conditions. The non-stationary nature of thermal processes occurring during space heating is taken into account by special calculations based on the theory of thermal stability.

Determination of the estimated thermal power of the heating system.

Calculated thermal power of CO - compilation of heat balance in heated rooms at design temperature outdoor air tн.р, = average temperature of the coldest five-day period with a supply of 0.92 tн.5 and determined for a specific construction area according to the standards of SP 131.13330.2012. Changing the current heat demand is a change in the heat supply to devices by changing the temperature and (or) the amount of coolant moving in the heating system - operational regulation.

In steady-state (stationary) mode, losses are equal to heat gains. Heat enters the room from people, technological and household equipment, sources artificial lighting, from heated materials, products, as a result of exposure to solar radiation on the building. IN production premises can be carried out technological processes associated with the release of heat (moisture condensation, chemical reactions, etc.).

To determine the estimated thermal power of the heating system, Qot, draws up a balance of heat consumption for the design conditions of the cold period of the year in the form

Qot = dQ = Qlimit + Qi(vent) ± Qt(life)
where Qlim - heat loss through external fences; Qi(vent) - heat consumption for heating the outside air entering the room; Qt(household) - technological or household emissions or heat consumption.

Q life =10*F floor (F floor – living rooms); Q vent = 0.3* Q limit. =Σ Q basic *Σ(β+1);

Q basic =F*k*Δt*n; where F- s limit of structures, k – heat transfer coefficient; k=1/R;

n – coefficient, position of external design limit to outside air (1-vertical, 0.4-floor, 0.9-ceiling)

β – additional heat loss, 1) in relation to the cardinal directions: N, E, NE, NW = 0.1, W, SE = 0.05, S, SW = 0.

2) for floors = 0.05 at t adv.<-30; 3) от входной двери = 0,27*h.

Annual heat costs for heating buildings.

In the cold season, in order to maintain a given temperature in a room, there must be equality between the amount of heat lost and received.

Annual heat consumption for heating

Q 0year = 24 Q ocp n, Gcal/year

n- duration of the heating period, days

Q ocp - average hourly heat consumption for heating during the heating period

Q ocp = Q 0 ·(t in - t av.o)/(t in - t r.o), Gcal/h

t in - average design temperature inside heated rooms, °C

t av.o - average outside air temperature for the period under consideration for a given area, °C

t p.o - design temperature of outside air for heating, °C.

Specific thermal characteristics of the building

It is an indicator of thermal engineering assessment of design and planning solutions and thermal efficiency of the building - q sp

For a building of any purpose, it is determined by the formula of Ermolaev N.S.: W/(m 3 0 C)

Where P is the perimeter of the building, m;

A – building area, m2;

q – coefficient taking into account glazing (ratio of glazing area to fence area);

φ 0 = q 0 =

k ok, k st, k pt, k pl – respectively, heat transfer coefficients of windows, walls, ceilings, floors, W/(m* 0 C), taken according to thermal calculation data;

H – building height, m.

The value of the specific thermal characteristic of the building is compared with the standard thermal characteristic for heating q 0 .

If the value of qsp differs from the standard q0 by no more than 15%, then the building meets thermal requirements. In case of a greater excess of the compared values, it is necessary to explain the possible reason and outline measures to improve the thermal performance of the building.

All buildings and structures, regardless of type and classification, have certain technical and operational parameters, which must be recorded in the appropriate documentation. One of the most important indicators is the specific thermal characteristic, which has a direct impact on the amount of payment for consumed thermal energy and allows you to determine the energy efficiency class of the structure.

The specific heating characteristic is usually called the value of the maximum heat flow that is necessary to heat the structure when the difference between the internal and external temperatures is equal to one degree Celsius. Average indicators are determined by building codes, recommendations and rules. At the same time, deviations from standard values ​​of any nature allow us to speak about the energy efficiency of the heating system.

The specific thermal characteristic can be either actual or calculated. In the first case, in order to obtain data as close as possible to reality, it is necessary to inspect the building using thermal imaging equipment, and in the second, the indicators are determined using a table of the specific heating characteristics of the building and special calculation formulas.

Recently, determining the energy efficiency class has become a mandatory procedure for all residential buildings. Such information should be included in the energy passport of the building, since each class has an established minimum and maximum energy consumption during the year.

To determine the energy efficiency class of a structure, it is necessary to clarify the following information:

• type of structure or building;
• building materials that were used in the construction and finishing of the building, as well as their technical parameters;
• deviation of actual and calculated-normative indicators. Factual data can be obtained by calculation or practical means. When making calculations, it is necessary to take into account the climatic characteristics of a particular area; in addition, regulatory data must include information on the costs of air conditioning, heat supply and ventilation.

Improving the energy efficiency of a multi-story building

Calculated data, in most cases, indicate low energy efficiency of multi-apartment housing. When it comes to increasing this indicator, it is necessary to clearly understand that heating costs can only be reduced by carrying out additional thermal insulation, which will help reduce heat loss. It is, of course, possible to reduce thermal energy losses in a residential apartment building, but solving this problem will be a very labor-intensive and expensive process.

The main methods for increasing the energy efficiency of a multi-storey building include the following:

• elimination of cold bridges in building structures (improvement of indicators by 2-3%);
• installation of window structures on loggias, balconies and terraces (the effectiveness of the method is 10-12%);
• use of micro-systems of micro-ventilation;
• replacement of windows with modern multi-chamber profiles with energy-saving double-glazed windows;
• bringing the area of ​​glazed structures to normal;
• increasing the thermal resistance of a building structure by finishing basement and technical rooms, as well as wall cladding using highly effective thermal insulation materials (increasing energy savings by 35-40%).

An additional measure to improve the energy efficiency of a multi-storey residential building could be for residents to carry out energy-saving procedures in their apartments, for example:

• installation of thermostats;
• installation of heat-reflecting screens;
• installation of thermal energy metering devices;
• installation of aluminum radiators;
• installation of an individual heating system;
• reduction of costs for ventilation of premises.

How to improve the energy efficiency of a private home?

You can increase the energy efficiency class of a private home using various techniques. An integrated approach to solving this problem will provide excellent results. The size of the cost item for heating a residential building is, first of all, determined by the features of the heat supply system. Individual housing construction practically does not involve connecting private houses to centralized heat supply systems, so heating issues in this case are resolved with the help of an individual boiler house. Installing modern boiler equipment, which is characterized by high efficiency and economical operation, will help reduce costs.

In most cases, gas boilers are used to supply heat to a private home, however, this type of fuel is not always appropriate, especially for areas that have not undergone gasification. When choosing a heating boiler, it is important to take into account the characteristics of the region, the availability of fuel and operating costs. No less important from an economic point of view for the future heating system will be the availability of additional equipment and options for the boiler. Installing a thermostat, as well as a number of other devices and sensors, will help save fuel.

Pumping equipment is mainly used to circulate coolant in autonomous heat supply systems. Undoubtedly, it must be of high quality and reliable. However, it should be remembered that the operation of equipment for forced circulation of coolant in the system will account for about 30-40% of the total energy costs. When choosing pumping equipment, preference should be given to models with energy efficiency class “A”.

The effectiveness of using thermostats deserves special attention. The principle of operation of the device is as follows: using a special sensor, it determines the internal temperature of the room and, depending on the obtained indicator, turns off or turns on the pump. The temperature regime and response threshold are set by the residents of the house independently. The main advantage of using a thermostat is that it turns off the circulation equipment and the heater. Thus, residents receive significant savings and a comfortable microclimate.

The installation of modern plastic windows with energy-saving double-glazed windows, thermal insulation of walls, protection of premises from drafts, etc. will also help to increase the actual specific thermal characteristics of a house. It should be noted that these measures will help increase not just the numbers, but also increase the comfort in the home, as well as reduce operating costs.

For thermal engineering assessment of structural and planning solutions and for approximate calculation of heat loss of buildings, the indicator used is the specific thermal characteristic of the building q.

The value q, W/(m 3 *K) [kcal/(h*m 3 *°C)], determines the average heat loss of 1 m 3 of the building, related to the calculated temperature difference equal to 1°:

q=Q building /(V(t p -t n)).

where Q building is the estimated heat loss from all rooms of the building;

V is the volume of the heated part of the building to the external measurement;

t p -t n - calculated temperature difference for the main rooms of the building.

The value q is determined as a product:

where q 0 is the specific thermal characteristic corresponding to the temperature difference Δt 0 =18-(-30)=48°;

β t is a temperature coefficient that takes into account the deviation of the actual calculated temperature difference from Δt 0.

The specific thermal characteristic q 0 can be determined by the formula:

q0=(1/(R 0 *V))*.

This formula can be transformed into a simpler expression using the data given in SNiP and taking, for example, the characteristics for residential buildings as a basis:

q 0 =((1+2d)*Fс+F p)/V.

where R 0 is the heat transfer resistance of the outer wall;

η ok - coefficient that takes into account the increase in heat loss through windows compared to external walls;

d is the proportion of the area of ​​the external walls occupied by windows;

ηpt, ηpl - coefficients that take into account the reduction in heat loss through the ceiling and floor compared to external walls;

F c - area of ​​external walls;

F p - area of ​​the building in plan;

V is the volume of the building.

Dependence of the specific thermal characteristic q 0 on changes in the structural and planning solution of the building, the volume of the building V and the heat transfer resistance of the external walls β relative to R 0, the height of the building h, the degree of glazing of the external walls d, the heat transfer coefficient of windows k it and the width of the building b.

Temperature coefficient β t is equal to:

βt=0.54+22/(t p -t n).

The formula corresponds to the values ​​of the coefficient β t, which are usually given in reference literature.

Characteristic q is convenient to use for thermal engineering assessment of possible structural and planning solutions for a building.

If we substitute the value of Q in the formula, it can be reduced to the form:

q=(∑k*F*(t p -t n))/(V(t p -t n))≈(∑k*F)/V.

The magnitude of the thermal characteristic depends on the volume of the building and, in addition, on the purpose, number of storeys and shape of the building, the area and thermal protection of external fences, the degree of glazing of the building and the construction area. The influence of individual factors on the value of q is obvious from consideration of the formula. The figure shows the dependence of qo on various characteristics of the building. The reference point in the drawing through which all curves pass corresponds to the following values: q o =O.415 (0.356) for a building V=20*103 m 3, width b=11 m, d=0.25 R o =0.86 (1.0), k ok =3.48 (3.0); length l=30 m. Each curve corresponds to a change in one of the characteristics (additional scales along the abscissa axis), all other things being equal. The second scale on the y-axis shows this dependence as a percentage. The graph shows that the degree of glazing d and the width of the building b have a noticeable effect on qo.

The graph shows the effect of thermal protection of external enclosures on the total heat loss of the building. Based on the dependence of qo on β (R o =β*R o.t.), we can conclude that with an increase in the thermal insulation of walls, the thermal performance decreases slightly, whereas when it decreases, qo begins to increase rapidly. With additional thermal protection of window openings (scale k ok), qo noticeably decreases, which confirms the feasibility of increasing the heat transfer resistance of windows.

Values ​​of q for buildings of various purposes and volumes are given in reference books. For civil buildings these values ​​vary within the following limits:

The heat demand for heating a building can differ markedly from the amount of heat loss, so instead of q, you can use the specific thermal characteristic of heating the building qot, when calculating the upper formula, the numerator is substituted not for heat loss, but for the installed thermal power of the heating system Q from set.

Q from.set =1,150*Q from.

where Q from - is determined by the formula:

Q from =ΔQ=Q orp +Q vent +Q tech.

where Q orp is heat loss through external fences;

Q fan - heat consumption to heat the air entering the room;

Q techn - technological and household heat emissions.

The qot values ​​can be used to calculate the heat demand for heating a building using aggregated meters using the following formula:

Q= q from *V*(tп-tн).

Calculation of heat loads on heating systems using enlarged meters is used for approximate calculations when determining the heat demand of a region, city, when designing a central heating supply, etc.

The specific heating characteristic of a building is a very important technical parameter. Its calculation is necessary to carry out design and construction work; in addition, knowledge of this parameter will not hurt the consumer, since it affects the amount of payment for thermal energy. Below we will look at what the specific heating characteristic is and how it is calculated.

The concept of specific thermal characteristics

Before getting acquainted with the calculations, let's define the basic terms. So, the specific thermal characteristic of a building for heating is the value of the largest heat flow that is necessary to heat the house. When calculating this parameter, the temperature delta, i.e. The difference between room and street temperatures is usually taken as one degree.

In essence, this indicator determines the energy efficiency of the building.

Average parameters are determined by regulatory documentation, such as:

• Construction rules and recommendations;
• SNiPs, etc.

Any deviation from the designated standards in any direction allows you to get an idea of ​​the energy efficiency of the heating system. The calculation of the parameter is carried out according to SNiP and other current methods.

Calculation method

The thermal specific characteristics of buildings are:

• Actual– to obtain accurate indicators, thermal imaging inspection of the structure is used.
• Calculation and normative– determined using tables and formulas.

Below we will consider in more detail the features of the calculation of each type.

Advice! To obtain the thermal characteristics of your home, you can contact specialists. True, the cost of such calculations can be significant, so it is more advisable to perform them yourself.

In the photo - a thermal imager for inspecting buildings

Calculation and standard indicators

Estimated indicators can be obtained using the following formula:

q building = + +n 1 * + n 2), where:

It must be said that this formula is not the only one. The specific heating characteristics of buildings can be determined according to local building codes, as well as certain methods of self-regulatory organizations, etc.

The calculation of the actual thermal characteristics is carried out using the following formula

This formula is based on actual parameters:

It should be noted that this equation is simple, as a result of which it is often used in calculations. However, it has a serious drawback that affects the accuracy of the resulting calculations. Namely, it takes into account the temperature difference in the premises of the building.

To get more accurate data with your own hands, you can use calculations to determine heat consumption by:

• Indicators of heat loss through various building structures;
• Project documentation.
• Aggregated indicators.

Self-regulatory organizations usually use their own methods.

They take into account the following parameters:

• Architectural and planning data;
• Year the house was built;
• Correction factors for outdoor air temperature during the heating season.

In addition, the actual specific heating characteristics of residential buildings should be determined taking into account heat losses in pipelines passing through “cold” rooms, as well as the cost of air conditioning and ventilation. These coefficients can be found in special SNiP tables.

This is, perhaps, all the basic instructions for determining the specific thermal parameter.

Energy efficiency class

Specific heat characteristics serve as the basis for obtaining such an indicator as the energy efficiency class of a house. In recent years, the energy efficiency class must be determined mandatory for residential multi-apartment buildings.

This parameter is determined based on the following data:

• Deviation of actual indicators and calculated and normative data. Moreover, the former can be obtained both by calculation and by practical means, i.e. using thermal imaging examination.
• Climatic features of the area.
• Regulatory data, which should include information on heating costs, as well as.
• Building type.
• Technical characteristics of the building materials used.

Each class has certain energy consumption values ​​throughout the year. The energy efficiency class must be noted in the energy passport of the house.

Conclusion

The specific heating characteristics of buildings is an important parameter that depends on a number of factors. As we found out, you can determine it yourself, which will allow you in the future.

You can get some additional information on this topic from the video in this article.