Specific consumption of thermal energy for heating a building: general concepts.

Explanations to the calculator of the annual consumption of thermal energy for heating and ventilation.

Initial data for calculation:

• The main characteristics of the climate where the house is located:
  • Average outdoor temperature of the heating period t o.p;
  • Duration of the heating period: this is the period of the year with an average daily outdoor temperature of not more than +8°C - z o.p.
• The main characteristic of the climate inside the house: the estimated temperature of the indoor air t w.r, °С
• Main thermal characteristics at home: specific annual consumption of thermal energy for heating and ventilation, referred to degree-days of the heating period, Wh / (m2 °C day).

Climate characteristics.

Climate parameters for calculating heating in cold period for different cities of Russia can be found here: (Map of climatology) or in SP 131.13330.2012 “SNiP 23-01–99* “Construction climatology”. Updated Edition»
For example, the parameters for calculating heating for Moscow ( Parameters B) such:

• Average outdoor temperature during the heating period: -2.2 °C
• Duration of the heating period: 205 days. (for a period with an average daily outdoor temperature of not more than +8°C).

Indoor air temperature.

You can set your own design temperature of the indoor air, or you can take it from the standards (see the table in Figure 2 or in the Table 1 tab).

The value used in the calculations is D d - degree-day of the heating period (GSOP), ° С × day. In Russia, the GSOP value is numerically equal to the product of the difference in the average daily outdoor air temperature over heating season(OP) t o.p and design indoor air temperature in the building t v.r for the duration of the OP in days: D d = ( t o.p - t w.r) z o.p.

Specific annual heat energy consumption for heating and ventilation

Normalized values.

Specific consumption thermal energy for heating residential and public buildings during the heating period should not exceed the values ​​\u200b\u200bgiven in the table according to SNiP 23-02-2003. Data can be taken from the table in picture 3 or calculated on tab Table 2(reworked version from [L.1]). According to it, select the value of the specific annual consumption for your house (area / number of floors) and insert it into the calculator. This is a characteristic of the thermal qualities of the house. All residential buildings under construction permanent residence must meet this requirement. The basic and normalized by years of construction specific annual consumption of thermal energy for heating and ventilation are based on draft order of the Ministry of Regional Development of the Russian Federation "On approval of the requirements for the energy efficiency of buildings, structures, structures", which specifies the requirements for basic characteristics(draft dated 2009), to the characteristics normalized from the moment the order was approved (conditionally designated N.2015) and from 2016 (N.2016).

Estimated value.

This value of the specific heat energy consumption can be indicated in the project of the house, it can be calculated on the basis of the project of the house, it can be estimated based on real thermal measurements or the amount of energy consumed for heating per year. If this value is in Wh/m2 , then it must be divided by the GSOP in ° C days, the resulting value should be compared with the normalized value for a house with a similar number of storeys and area. If it is less than normalized, then the house meets the requirements for thermal protection, if not, then the house should be insulated.

Your numbers.

The values ​​of the initial data for the calculation are given as an example. You can paste your values ​​into the fields on the yellow background. Insert reference or calculated data into the fields on a pink background.

What can the calculation results say?

Specific annual heat energy consumption, kWh/m2 - can be used to estimate required amount of fuel per year for heating and ventilation. By the amount of fuel, you can choose the capacity of the tank (warehouse) for fuel, the frequency of its replenishment.

Annual consumption of thermal energy, kWh is the absolute value of energy consumed per year for heating and ventilation. By changing the values ​​of the internal temperature, you can see how this value changes, evaluate the savings or waste of energy from a change in the temperature maintained inside the house, see how the inaccuracy of the thermostat affects energy consumption. This will be especially evident in terms of rubles.

Degree-days of the heating period,°С day - characterize the climatic conditions external and internal. By dividing by this number the specific annual consumption of thermal energy in kWh / m2, you will get a normalized characteristic of the thermal properties of the house, decoupled from climatic conditions (this can help in choosing a house project, heat-insulating materials).

On the accuracy of calculations.

In the territory Russian Federation climate change is taking place. A study of the evolution of climate has shown that there is currently a period of global warming. According to the assessment report of Roshydromet, the climate of Russia has changed more (by 0.76 °C) than the climate of the Earth as a whole, with the most significant changes occurring on European territory our country. On fig. Figure 4 shows that the increase in air temperature in Moscow over the period 1950–2010 occurred in all seasons. It was most significant during the cold period (0.67 ° C for 10 years). [L.2]

The main characteristics of the heating period are the average temperature heating season, °С, and the duration of this period. Naturally, every year real value changes and, therefore, calculations of the annual consumption of thermal energy for heating and ventilation of houses are only an estimate of the actual annual consumption of thermal energy. The results of this calculation allow compare .

Appendix:

Literature:

• 1. Refinement of tables of basic and normalized by years of construction indicators of energy efficiency of residential and public buildings
  V. I. Livchak, Ph.D. tech. Sciences, independent expert
• 2. New SP 131.13330.2012 “SNiP 23-01–99* “Construction climatology”. Updated Edition»
  N. P. Umnyakova, Ph.D. tech. Sciences, Deputy Director for scientific work NIISF RAASN

As noted in the introduction, when choosing the requirements of the thermal protection indicator "c", the value of the specific consumption of thermal energy for heating is normalized. This is a complex value that takes into account energy savings from the use of architectural, construction, heat engineering and engineering solutions, aimed at saving energy resources, and therefore it is possible, if necessary, in each specific case to establish less than the normalized heat transfer resistance for certain types enclosing structures. The specific consumption of thermal energy depends on the heat-shielding properties of the enclosing structures, space-planning decisions of the building, heat emissions and the amount solar energy entering the premises of the building, efficiency engineering systems maintaining the required microclimate of premises and heat supply systems.

, kJ / (m 2 ° C day) or [kJ / (m 3 ° C day)], is determined by the formula

or

, (5.1)

where is the consumption of thermal energy for heating the building during the heating period, MJ;

Heated area of ​​apartments or useful area of ​​premises, m 2;

Heated volume of the building, m 3;

D - degree-day of the heating period, °С day (1.1).

Specific consumption of thermal energy for heating buildings must be less than or equal to the specified value

≤ .(5.2)

5.1. Determination of heated areas and building volumes

for residential and public buildings.

1. The heated area of ​​the building should be defined as the area of ​​floors (including the attic, heated basement and basement) of the building, measured within the inner surfaces of the outer walls, including the area occupied by partitions and interior walls. At the same time, the area staircases and elevator shafts is included in the floor area.

The heated area of ​​the building does not include areas warm attics and basements, unheated technical floors, basement (underground), cold unheated verandas, unheated staircases, as well as a cold attic or part of it not occupied by an attic.

2. When determining the area attic floor takes into account the area with a height of up to sloped ceiling 1.2 m at an inclination of 30 ° to the horizon; 0.8 m - at 45° - 60°; at 60 ° and more - the area is measured to the plinth.

3. The area of ​​residential premises of the building is calculated as the sum of the areas of all common rooms(living rooms) and bedrooms.

4. The heated volume of the building is defined as the product of the heated area of ​​the floor by the internal height, measured from the floor surface of the first floor to the ceiling surface last floor.

At complex forms of the internal volume of a building, the heated volume is defined as the volume of space bounded by the internal surfaces of external enclosures (walls, coverings or attic floor, basement).

5. The area of ​​external enclosing structures is determined by the internal dimensions of the building. The total area of ​​the outer walls (including window and doorways) is defined as the product of the perimeter of the outer walls by inner surface to the internal height of the building, measured from the surface of the floor of the first floor to the surface of the ceiling of the last floor, taking into account the area of ​​window and door slopes with a depth from the inner surface of the wall to the inner surface of the window or door block. The total area of ​​windows is determined by the size of the openings in the light. The area of ​​the outer walls (opaque part) is determined as the difference total area external walls and area of ​​windows and external doors.

6. The area of ​​horizontal external fences (covering, attic and basement floors) is defined as the floor area of ​​the building (within the inner surfaces of the outer walls).

With inclined surfaces of the ceilings of the last floor, the area of ​​coverage, attic floor is defined as the area of ​​the inner surface of the ceiling.

The calculation of the areas and volumes of the space-planning decision of the building is carried out according to the working drawings of the architectural and construction part of the project. As a result, the following main volumes and areas are obtained:

Heated volume V h , m 3;

Heated area (for residential buildings - total area of ​​apartments) A h , m 2;

The total area of ​​the external building envelope, m 2.

5.2. Determination of the normalized value of the specific consumption of thermal energy for heating the building

Normalized value of the specific consumption of thermal energy for heating a residential or public building determined according to the table. 5.1 and 5.2.

Normalized specific consumption of thermal energy for heating residential houses single-family separately

standing and blocked, kJ / (m 2 ° C day)

Table 5.1

Normalized specific consumption of thermal energy per

heating of buildings, kJ / (m 2 ° C day) or

[kJ / (m 3 ° C day)]

Table 5.2

5.3. Determination of the estimated specific consumption of thermal energy for heating the building

This item is not implemented in term paper, and in the section of the graduation project is carried out in agreement with the supervisor and consultant.

The calculation of the specific consumption of thermal energy for heating residential and public buildings is carried out using Appendix D of SNiP 23-02 and the methodology of Appendix I.2 ​​of SP 23-101-2004.

5.4. Determination of the calculated indicator of the compactness of the building

This item is carried out in the section of the graduation project for residential buildings and is not included in coursework.

Estimated indicator the compactness of the building is determined by the formula:

, (5.3)

where and V h are found in clause 5.1.

The calculated indicator of the compactness of residential buildings should not exceed the following normalized values:

0.25 - for 16-storey buildings and above;

0.29 - for buildings from 10 to 15 floors inclusive;

0.32 - for buildings from 6 to 9 floors inclusive;

0.36 - for 5-storey buildings;

0.43 - for 4-storey buildings;

0.54 - for 3-storey buildings;

0.61; 0.54; 0.46 - for two-, three- and four-storey blocked and sectional houses, respectively;

0.9 - for two- and one-story houses with an attic;

1.1 - for one-story houses.

If the calculated value is greater than the normalized value, then it is recommended to change the space-planning solution in order to achieve the normalized value.

LITERATURE

1. SNiP 23-01-99 Building climatology. – M.: Gosstroy of Russia, 2004.

2. SNiP 23-02-2003 Thermal protection buildings. – M.: Gosstroy of Russia, 2004.

3. SP 23-01-2004 Design of thermal protection of buildings. – M.: Gosstroy of Russia, 2004.

4. Karaseva L.V., Chebanova E.V., Geppel S.A. Thermal physics of enclosing structures of architectural objects: Tutorial. - Rostov-on-Don, 2008.

5. Fokin K.F. Structural heat engineering of enclosing parts of buildings / Ed. Yu.A. Tabunshchikova, V.G. Gagarin. – 5th ed., revision. – M.: AVOK-PRESS, 2006.

APPENDIX A

What is it - the specific consumption of thermal energy for heating a building? Is it possible to calculate the hourly heat consumption for heating in a cottage with your own hands? This article will be devoted to terminology and general principles calculation of the need for thermal energy.

The basis of new building projects is energy efficiency.

Terminology

What is specific heat consumption for heating?

We are talking about the amount of heat energy that must be brought inside the building in terms of each square or cubic meter to maintain normalized parameters in it, comfortable for work and living.

Usually, a preliminary calculation of heat losses is carried out according to enlarged meters, that is, based on the average thermal resistance of the walls, the approximate temperature in the building and its total volume.

Factors

What affects the annual heat consumption for heating?

• Duration of the heating season (). It, in turn, is determined by the dates when average daily temperature on the street for the last five days will drop below (and rise above) 8 degrees Celsius.

Useful: in practice, when planning the start and stop of heating, the weather forecast is taken into account. Long thaws occur in winter, and frosts can strike as early as September.

• Average temperatures of the winter months. Usually when designing heating system the average monthly temperature of the coldest month, January, is taken as a guideline. It is clear that the colder it is outside, the more heat the building loses through the building envelope.

• The degree of thermal insulation of the building greatly affects what will be the rate of thermal power for him. An insulated facade can reduce the need for heat by half relative to a wall made of concrete slabs or brick.
• building glazing factor. Even when using multi-chamber double-glazed windows and energy-saving spraying, noticeably more heat is lost through windows than through walls. How most of the facade is glazed - the greater the need for heat.
• The degree of illumination of the building. On a sunny day, a surface oriented perpendicular to the sun's rays can absorb up to a kilowatt of heat per square meter.

Clarification: in practice, the exact calculation of the amount of solar heat absorbed will be extremely difficult. Those same glass facades, which lose heat in cloudy weather, will serve as heating in sunny weather. The orientation of the building, the slope of the roof, and even the color of the walls will all affect the ability to absorb solar heat.

Calculations

Theory is theory, but how heating costs are calculated in practice country house? Is it possible to estimate the estimated costs without plunging into the abyss of complex heat engineering formulas?

Consumption of the required amount of thermal energy

Instructions for calculating the estimated amount required heat relatively simple. The key phrase is an approximate amount: for the sake of simplifying calculations, we sacrifice accuracy, ignoring a number of factors.

• The base value of the amount of thermal energy is 40 watts per cubic meter of cottage volume.
• To the base value is added 100 watts for each window and 200 watts for each door in the exterior walls.

• Further, the obtained value is multiplied by a coefficient, which is determined by the average amount of heat loss through the outer contour of the building. For apartments in the center apartment building take the coefficient equal to one: only losses through the facade are noticeable. Three of the four walls of the contour of the apartment border on warm rooms.

For corner and end apartments, a coefficient of 1.2 - 1.3 is taken, depending on the material of the walls. The reasons are obvious: two or even three walls become external.

Finally, in a private house, the street is not only along the perimeter, but also from below and above. In this case, a coefficient of 1.5 is applied.

Please note: for apartments on the extreme floors, if the basement and attic are not insulated, it is also quite logical to use a coefficient of 1.3 in the middle of the house and 1.4 at the end.

• Finally received thermal power multiplied by the regional coefficient: 0.7 for Anapa or Krasnodar, 1.3 for St. Petersburg, 1.5 for Khabarovsk and 2.0 for Yakutia.

In the cold climate zone- special heating requirements.

Let's calculate how much heat is needed for a cottage measuring 10x10x3 meters in the city of Komsomolsk-on-Amur, Khabarovsk Territory.

The volume of the building is 10*10*3=300 m3.

Multiplying the volume by 40 watts/cube will give 300*40=12000 watts.

Six windows and one door is another 6*100+200=800 watts. 1200+800=12800.

Private house. Coefficient 1.5. 12800*1.5=19200.

Khabarovsk region. We multiply the need for heat by another one and a half times: 19200 * 1.5 = 28800. In total - at the peak of frost, we need about a 30-kilowatt boiler.

Calculation of heating costs

The easiest way to calculate the consumption of electricity for heating: when using an electric boiler, it is exactly equal to the cost of thermal power. With continuous consumption of 30 kilowatts per hour, we will spend 30 * 4 rubles (approximate current price of a kilowatt-hour of electricity) = 120 rubles.

Fortunately, the reality is not so nightmarish: as practice shows, the average heat demand is about half the calculated one.

• Firewood - 0.4 kg / kW / h. Thus, the approximate norms for the consumption of firewood for heating in our case will be equal to 30/2 (the rated power, as we remember, can be divided in half) * 0.4 \u003d 6 kilograms per hour.
• The consumption of brown coal in terms of a kilowatt of heat is 0.2 kg. The consumption rates of coal for heating are calculated in our case as 30/2*0.2=3 kg/h.

Brown coal is a relatively inexpensive heat source.

• For firewood - 3 rubles (the cost of a kilogram) * 720 (hours in a month) * 6 (hourly consumption) \u003d 12960 rubles.
• For coal - 2 rubles * 720 * 3 = 4320 rubles (read others).

Conclusion

You can, as usual, find additional information on cost calculation methods in the video attached to the article. Warm winters!