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Gas is still the cheapest type of fuel, but the cost of connection is sometimes very high, so many people want to first assess how economically justified such costs are. To do this, you need to know the gas consumption for heating, then it will be possible to estimate the total cost and compare it with other types of fuel.
Method of calculation for natural gas
The approximate gas consumption for heating is calculated based on half the capacity of the installed boiler. The thing is that when determining the power of a gas boiler, the lowest temperature is laid. This is understandable – even when it is very cold outside, the house should be warm.
But it is completely wrong to calculate the gas consumption for heating according to this maximum figure – after all, in general, the temperature is much higher, which means that much less fuel is burned. Therefore, it is customary to consider the average fuel consumption for heating – about 50% of the heat loss or boiler power.
We calculate the gas consumption by heat loss
If there is no boiler yet, and you estimate the cost of heating in different ways, you can calculate from the total heat loss of the building. They are most likely familiar to you. The methodology here is as follows: they take 50% of the total heat loss, add 10% to provide hot water supply and 10% to heat outflow during ventilation. As a result, we get the average consumption in kilowatts per hour.
Next, you can find out the fuel consumption per day (multiply by 24 hours), per month (by 30 days), if desired – for the entire heating season (multiply by the number of months during which the heating works). All these figures can be converted into cubic meters (knowing the specific heat of combustion of gas), and then multiply cubic meters by the price of gas and, thus, find out the cost of heating.
| The name of the crowd | Unit | Specific heat of combustion in kcal | Specific heating value in kW | Specific calorific value in MJ |
|---|---|---|---|---|
| Natural gas | 1 m 3 | 8000 kCal | 9,2 кВт | 33,5 MJ |
| Liquefied gas | 1 kg | 10800 kCal | 12,5 кВт | 45,2 MJ |
| Hard coal (W=10%) | 1 kg | 6450 kCal | 7,5 кВт | 27 MJ |
| wood pellet | 1 kg | 4100 kcal | 4,7 кВт | 17,17 MJ |
| Dried wood (W=20%) | 1 kg | 3400 kcal | 3,9 кВт | 14,24 MJ |
Heat loss calculation example
Let the heat loss of the house be 16 kW / h. Let’s start counting:
- average heat demand per hour – 8 kW / h + 1,6 kW / h + 1,6 kW / h = 11,2 kW / h;
- per day – 11,2 kW * 24 hours = 268,8 kW;
- per month – 268,8 kW * 30 days = 8064 kW.
The actual gas consumption for heating still depends on the type of burner – modulated are the most economical
Convert to cubic meters. If we use natural gas, we divide the gas consumption for heating per hour: 11,2 kW / h / 9,3 kW = 1,2 m3 / h. In calculations, the figure 9,3 kW is the specific heat capacity of natural gas combustion (available in the table).
By the way, you can also calculate the required amount of fuel of any type – you just need to take the heat capacity for the required fuel.
Since the boiler does not have 100% efficiency, but 88-92%, you will still have to make adjustments for this – add about 10% of the figure obtained. In total, we get the gas consumption for heating per hour – 1,32 cubic meters per hour. You can then calculate:
- consumption per day: 1,32 m3 * 24 hours = 28,8 m3/day
- demand per month: 28,8 m3 / day * 30 days = 864 m3 / month.
The average consumption for the heating season depends on its duration – we multiply it by the number of months that the heating season lasts.
This calculation is approximate. In some month, gas consumption will be much less, in the coldest – more, but on average the figure will be about the same.
Boiler power calculation
Calculations will be a little easier if there is a calculated boiler capacity – all the necessary reserves (for hot water supply and ventilation) are already taken into account. Therefore, we simply take 50% of the calculated capacity and then calculate the consumption per day, month, per season.
For example, the design capacity of the boiler is 24 kW. To calculate the gas consumption for heating, we take half: 12 k / W. This will be the average need for heat per hour. To determine the fuel consumption per hour, we divide by the calorific value, we get 12 kW / h / 9,3 k / W = 1,3 m3. Further, everything is considered as in the example above:
- per day: 12 kW / h * 24 hours = 288 kW in terms of the amount of gas – 1,3 m3 * 24 = 31,2 m3
- per month: 288 kW * 30 days = 8640 m3, consumption in cubic meters 31,2 m3 * 30 = 936 m3.
You can calculate gas consumption for heating a house according to the design capacity of the boiler
Next, we add 10% for the imperfection of the boiler, we get that for this case the flow rate will be slightly more than 1000 cubic meters per month (1029,3 cubic meters). As you can see, in this case everything is even simpler – fewer numbers, but the principle is the same.
Per square meter
Even more approximate calculations can be obtained by the quadrature of the house. There are two ways:
- It can be calculated according to SNiP standards – for heating one square meter in Central Russia, an average of 80 W / m2 is required. This figure can be applied if your house is built according to all requirements and has good insulation.
- You can estimate according to the average data:
- with good house insulation, 2,5-3 cubic meters / m2 are required;
- with average insulation, gas consumption is 4-5 cubic meters / m2.
The better the house is insulated, the less gas consumption for heating will be.
Each owner can evaluate the degree of insulation of his house, respectively, you can estimate what gas consumption will be in this case. For example, for a house of 100 sq. m. with average insulation, 400-500 cubic meters of gas will be required for heating, 150-600 cubic meters per month for a house of 750 square meters, 200-2 cubic meters of blue fuel for heating a house of 800 m100. All this is very approximate, but the figures are based on many factual data.
Calculation of the consumption of liquefied gas
Many boilers can run on LPG. How beneficial is it? What will be the consumption of liquefied gas for heating? All this can also be calculated. The technique is the same: you need to know either heat loss or boiler power. Next, we translate the required amount into liters (units of measurement of liquefied gas), and if desired, we consider the number of required cylinders.
Let’s look at the calculation with an example. Let the boiler power be 18 kW, respectively, the average heat demand is 9 kW / h. When burning 1 kg of liquefied gas, we get 12,5 kW of heat. So, to get 9 kW, you need 0,72 kg (9 kW / 12,5 kW = 0,72 kg).
Next, we consider:
- per day: 0,72 kg * 24 hours = 17,28 kg;
- per month 17,28 kg * 30 days = 518,4 kg.
Let’s add a correction for the efficiency of the boiler. It is necessary to look in each specific case, but let’s take 90%, that is, add another 10%, it turns out that the monthly consumption will be 570,24 kg.
To calculate the number of cylinders, we divide this figure by 21,2 kg (this is how much, on average, there is a kg of gas in a 50 liter cylinder).
In total, this boiler will require 27 cylinders of liquefied gas. And consider the cost yourself – prices vary by region. But don’t forget about shipping costs. By the way, they can be reduced if you make a gas tank – a sealed container for storing liquefied gas, which can be refueled once a month or less – depending on the storage volume and needs.
And again, do not forget that this is only an approximate figure. In cold months, gas consumption for heating will be more, in warm months – much less.
PS If it is more convenient for you to calculate the consumption in liters:
- 1 liter of liquefied gas weighs approximately 0,55 kg and, when burned, gives approximately 6500 kW of heat;
- There are about 50 liters of gas in a 42 liter bottle.