What is a unit of measurement called a gigacalorie? What does it have to do with traditional kilowatt-hours, in which thermal energy is calculated? What information do you need to have in order to correctly calculate Gcal for heating? Finally, what formula should be used during the calculation? This, as well as many other things, will be discussed in today’s article.
Calculation of Gcal for heating
- 1 What is Gcal?
- 2 What is all this for? 2.1 Multi-apartment buildings
- 2.2 Private houses
- 3.1 Vane meters
- 5.1 Video - How to calculate heating in a private house
What is Gcal?
We should start with a related definition. A calorie refers to the specific amount of energy required to heat one gram of water to one degree Celsius (at atmospheric pressure, of course). And due to the fact that from the point of view of heating costs, say, at home, one calorie is a tiny amount, gigacalories (or Gcal for short), corresponding to one billion calories, are used for calculations in most cases. We've decided on this, let's move on.
The use of this value is regulated by the relevant document of the Ministry of Fuel and Energy, published back in 1995.
Note! On average, the consumption standard in Russia per square meter is 0.0342 Gcal per month. Of course, this figure may vary for different regions, since everything depends on climatic conditions.
So, what is a gigacalorie if we “transform” it into values that are more familiar to us? See for yourself.
1. One gigacalorie is equal to approximately 1,162.2 kilowatt-hours.
2. One gigacalorie of energy is enough to heat a thousand tons of water to +1°C.
Summary of all calculations
Correctly performed calculation of thermal energy consumption is the key to economical expenditure of funds spent on heating. Giving an example of the average value, it can be noted that when heating a residential building with an area of 200 m² in accordance with the calculation formulas described above, the volume of heat will be approximately 3 Gcal per month. Thus, taking into account the fact that the standard heating season lasts six months, then over six months the consumption volume will be 18 Gcal.
Of course, all measures for calculating heat are much more convenient and easier to carry out in private buildings than in apartment buildings with a centralized heating system, where simple equipment cannot be used.
What is all this for?
The problem should be considered from two points of view - from the point of view of apartment buildings and private ones. Let's start with the first ones.
Apartment buildings
There is nothing complicated here: gigacalories are used in thermal calculations. And if you know how much thermal energy remains in the house, then you can present the consumer with a specific bill. Let's give a small comparison: if centralized heating operates in the absence of a meter, then you have to pay according to the area of the heated room. If there is a heat meter, this in itself implies a horizontal wiring type (either collector or serial): two risers are brought into the apartment (for “return” and supply), and the intra-apartment system (more precisely, its configuration) is determined by the residents. This kind of scheme is used in new buildings, thanks to which people regulate the consumption of thermal energy, making a choice between savings and comfort.
Let's find out how this adjustment is carried out.
1. Installation of a general thermostat on the return line. In this case, the flow rate of the working fluid is determined by the temperature inside the apartment: if it decreases, the flow rate will accordingly increase, and if it increases, it will decrease.
2. Throttling of heating radiators. Thanks to the throttle, the passage of the heating device is limited, the temperature decreases, and therefore the consumption of thermal energy is reduced.
Private houses
We continue to talk about calculating Gcal for heating. Owners of country houses are interested, first of all, in the cost of a gigacalorie of thermal energy obtained from one or another type of fuel. The table below may help with this.
Table. Comparison of cost of 1 Gcal (including transport costs)
Name of energy resource | Approximate cost, in rubles* |
Gas (liquefied) | 520 |
Gas (natural) | 3 300 |
Coal | 550 |
Diesel fuel | 3 270 |
Pellets | 1 800 |
Electric Energy | 4 300 |
* - prices are approximate, since tariffs may differ depending on the region, moreover, they are constantly growing.
Option 2
Now we will calculate payments in conditions where the house is equipped with a common heating meter, and some of the apartments are also equipped with individual meters. As in the previous case, the calculation will be carried out according to two positions (thermal energy consumption for housing and ODN).
We will need formula No. 1 and No. 2 (accrual rules according to controller readings or taking into account heat consumption standards for residential premises in Gcal). Calculations will be carried out relative to the area of the residential building and apartment from the previous version.
Calculation 1
- 1.3 gigacalories – individual meter readings;
- RUR 1,1820 – approved tariff.
https://youtube.com/watch?v=dFLW96z0YVk
- Is 0.025 Gcal a standard indicator of heat consumption per 1 m2? area in the apartment;
- 70 m? – square footage of the apartment;
- 1,400 rub. – tariff for thermal energy.
Next, we calculate the second component of our payment (ODN) using two formulas - No. 13 (volume of service) and No. 10 (heating cost).
Calculation 2
- 300 gcal – readings of the common house meter;
- 12 Gcal – the amount of thermal energy used to heat non-residential premises;
- 6,000 m? – the sum of the area of all residential premises;
- 0.025 – standard (heat energy consumption for apartments);
- 9 Gcal – the sum of indicators from the meters of all apartments that are equipped with metering devices;
- 35 Gcal – the amount of heat spent on supplying hot water in the absence of a centralized supply;
- 70 m? – area of the apartment;
- 8,000 m? – total area (all residential and non-residential premises in the house).
https://youtube.com/watch?v=tGvIg-I1QCU
Please note that this option includes only the actual volumes of energy consumed and if your house is equipped with a centralized hot water supply, then the amount of heat spent on hot water supply needs is not taken into account. The same applies to non-residential premises: if they are not in the house, then they will not be included in the calculation
- 1.425 gcal – amount of heat (AT);
- 1,400 rub. – approved tariff.
As a result of the calculations, we found out that the full payment for heating will be:
- 1820 + 1995 = 3,815 rubles. - with an individual counter.
- 2,450 + 1995 = 4,445 rubles. - without an individual device.
Heat meters
Now let’s find out what information is needed in order to calculate the heating. It's easy to guess what this information is.
1. Temperature of the working fluid at the outlet/inlet of a specific section of the pipeline.
2. The flow rate of the working fluid that passes through the heating devices.
Consumption is determined through the use of heat metering devices, that is, meters. These can be of two types, let’s get acquainted with them.
Vane meters
Such devices are intended not only for heating systems, but also for hot water supply. Their only difference from those meters that are used for cold water is the material from which the impeller is made - in this case it is more resistant to elevated temperatures.
As for the mechanism of operation, it is almost the same:
- due to the circulation of the working fluid, the impeller begins to rotate;
- the rotation of the impeller is transmitted to the accounting mechanism;
- transmission is carried out without direct interaction, but with the help of a permanent magnet.
Despite the fact that the design of such meters is extremely simple, their response threshold is quite low, moreover, there is reliable protection against distortion of readings: the slightest attempts to slow down the impeller through an external magnetic field are stopped thanks to an antimagnetic screen.
Devices with a difference recorder
Such devices operate on the basis of Bernoulli's law, which states that the speed of a gas or liquid flow is inversely proportional to its static movement. But how does this hydrodynamic property apply to calculations of working fluid flow? It’s very simple - you just need to block its path with a retaining washer. In this case, the rate of pressure drop on this washer will be inversely proportional to the speed of the moving flow. And if the pressure is recorded by two sensors at once, then the flow can be easily determined, and in real time.
Note! The design of the meter implies the presence of electronics. The vast majority of such modern models provide not only dry information (temperature of the working fluid, its consumption), but also determines the actual use of thermal energy. The control module here is equipped with a port for connecting to a PC and can be configured manually.
Many readers will probably have a logical question: what to do if we are not talking about a closed heating system, but about an open one, in which selection for hot water supply is possible? How to calculate Gcal for heating in this case? The answer is quite obvious: here pressure sensors (as well as retaining washers) are installed simultaneously on both the supply and the “return”. And the difference in the flow rate of the working fluid will indicate the amount of heated water that was used for domestic needs.
How to calculate the consumed thermal energy?
If for one reason or another there is no heat meter, then to calculate thermal energy you must use the following formula:
Vx(T1-T2)/1000=Q
Let's look at what these symbols mean.
1. V denotes the amount of hot water consumed, which can be calculated either in cubic meters or in tons.
2. T1 is the temperature indicator of the hottest water (traditionally measured in the usual degrees Celsius). In this case, it is preferable to use exactly the temperature that is observed at a certain operating pressure. By the way, the indicator even has a special name - enthalpy. But if the required sensor is missing, then as a basis you can take the temperature regime that is extremely close to this enthalpy. In most cases, the average is approximately 60-65 degrees.
3. T2 in the above formula also denotes the temperature, but of cold water. Due to the fact that it is quite difficult to penetrate the main line with cold water, constant values are used as this value, which can change depending on the climatic conditions outside. So, in winter, when the heating season is in full swing, this figure is 5 degrees, and in the summer, when the heating is turned off, 15 degrees.
4. As for 1000, this is the standard coefficient used in the formula in order to obtain the result in gigacalories. It will be more accurate than if you used calories.
5. Finally, Q is the total amount of thermal energy.
As you can see, there is nothing complicated here, so we move on. If the heating circuit is of a closed type (and this is more convenient from an operational point of view), then the calculations must be made slightly differently. The formula that should be used for a building with a closed heating system should look like this:
((V1x(T1-T)-(V2x(T2-T))=Q
Now, accordingly, to the decoding.
1. V1 indicates the flow rate of the working fluid in the supply pipeline (typically, not only water, but also steam can act as a source of thermal energy).
2. V2 is the flow rate of the working fluid in the return pipeline.
3. T is an indicator of the temperature of a cold liquid.
4. T1 – water temperature in the supply pipeline.
5. T2 – temperature indicator that is observed at the outlet.
6. And finally, Q is the same amount of thermal energy.
It is also worth noting that the calculation of Gcal for heating in this case depends on several notations:
- thermal energy that entered the system (measured in calories);
- temperature indicator during the removal of working fluid through the return pipeline.
All cases of using formulas for calculating heating fees in apartment buildings were analyzed by Elena Shereshovets
In the spring of 2022, the Constitutional Court of the Russian Federation is twice obliged to make changes to the calculation of heating fees in apartment buildings. As a result, new formulas appeared in RF PP No. 354. The head of the Expert Council of the P1 Association, Elena Shereshovets, in the new issue of the online magazine “Housing and Public Utilities: Dreams Come True” examined the changes that have occurred in the payment system for heat supply:
Watch the video on the YouTube channel of the P1 Association ➡️
How does the MA take into account expenses and their reimbursement by the debtor when limiting the CG
99912
Other ways to determine the amount of heat
Let us add that there are also other methods by which you can calculate the amount of heat that enters the heating system. In this case, the formula is not only slightly different from those given below, but also has several variations.
((V1x(T1-T2)+(V1-V2)x(T2-T1))/1000=Q
((V2x(T1-T2)+(V1-V2)x(T1-T)/1000=Q
As for the values of the variables, they are the same as in the previous paragraph of this article. Based on all this, we can confidently conclude that it is quite possible to calculate the heat for heating on your own. However, one should not forget about consulting with specialized organizations that are responsible for providing housing with heat, since their methods and principles of calculations may differ, significantly, and the procedure may consist of a different set of measures.
If you intend to equip a “warm floor” system, then prepare for the fact that the calculation process will be more complex, since it takes into account not only the characteristics of the heating circuit, but also the characteristics of the electrical network, which, in fact, will heat the floor. Moreover, the organizations that install this kind of equipment will also be different.
Note! People often encounter the problem of converting calories into kilowatts, which is explained by the use of a unit of measurement in many specialized manuals, which is called “C” in the international system.
In such cases, it is necessary to remember that the coefficient due to which kilocalories will be converted into kilowatts is equal to 850. In simpler terms, one kilowatt is 850 kilocalories. This calculation option is simpler than those given above, since the value in gigacalories can be determined in a few seconds, since a Gcal, as noted earlier, is a million calories.
In order to avoid possible mistakes, we should not forget that almost all modern heat meters operate with some error, albeit within acceptable limits. This error can also be calculated by hand, for which you need to use the following formula:
(V1- V2)/(V1+ V2)x100=E
Traditionally, now we find out what each of these variable values means.
1. V1 is the flow rate of the working fluid in the supply pipeline.
2. V2 – a similar indicator, but in the return pipeline.
3. 100 is the number by which the value is converted to a percentage.
4. Finally, E is the error of the accounting device.
According to operational requirements and standards, the maximum permissible error should not exceed 2 percent, although in most meters it is somewhere around 1 percent.
As a result, we note that a correctly calculated Gcal for heating can significantly save money spent on heating the room. At first glance, this procedure is quite complicated, but - and you have seen this personally - if you have good instructions, there is nothing difficult about it.
That's all. We also recommend watching the thematic video below. Good luck in your work and, as usual, have a warm winter!