Gas consumption for heating a house 100 m²: calculation features for liquefied and natural gas + examples with formulas

Amir Gumarov
Checked by a specialist: Amir Gumarov
Author: Angela Kravets
Last update: November 2019

Surely you have already heard repeatedly that gas boilers have no competitors in terms of efficiency. But, you see, healthy skepticism will never hurt - as they say, trust, but verify. Therefore, before deciding on the installation and operation of gas equipment, it is necessary to thoroughly calculate and think through everything.

We suggest that you familiarize yourself with the calculation steps and formulas that determine the gas consumption for heating a house 100 m2 taking into account all significant factors. Having familiarized yourself with the calculations, you can make your own conclusion on how profitable it is to use blue fuel as a source of thermal energy.

Thermal load and gas flow formulas

Gas consumption is conventionally indicated by the Latin letter V and is determined by the formula:

V = Q / (n / 100 x q)where

Q is the heat load on heating (kW / h), q is the calorific value of gas (kW / m³), ​​n is the efficiency of the gas boiler, expressed as a percentage.

The consumption of main gas is measured in cubic meters per hour (m³ / h), of liquefied gas in liters or kilograms per hour (l / h, kg / h).

Gas meters
The gas flow rate is calculated before designing the heating system, choosing a boiler, energy source, and then is easily controlled using meters

Let us consider in detail what the variables in this formula mean and how to define them.

The concept of "heat load" is given in the federal law "On Heat Supply". Changing the slightly official wording, we simply say that this is the amount of thermal energy transferred per unit time to maintain a comfortable temperature in the room.

In the future, we will also use the concept of “thermal power”, therefore, at the same time, we will also give its definition in relation to our calculations. Thermal power is the amount of thermal energy that a gas boiler can produce per unit of time.

Thermal load is determined in accordance with MDK 4-05.2004 by heat engineering calculations.

Simplified formula:

Q = V x ΔT x K / 860.

Here V is the volume of the room, which is obtained by multiplying the height of the ceiling, the width and length of the floor.

ΔT is the difference between the temperature of the air outside the building and the required temperature in the heated room. For calculations, the climatic parameters given in SP 131.13330.2012 are used.

Window to the south
To obtain the most accurate indicators of gas flow, formulas are used that even take into account the location of the windows - the sun's rays warm the room, reducing heat loss

K is the heat loss coefficient, which is most difficult to accurately determine due to the influence of many factors, including the number and position of the external walls relative to the cardinal points and the wind regime in winter; number, type and sizes of windows, entrance and balcony doors; type of construction and heat-insulating materials used and so on.

Bridges of cold
On the building envelope there are areas with increased heat transfer - cold bridges, because of which fuel consumption can increase significantly

If necessary, perform the calculation with an error within 5%, it is better to conduct a thermal audit of the house.

If the calculation requirements are not so stringent, you can use the average values ​​of the heat loss coefficient:

  • increased degree of thermal insulation - 0.6-0.9;
  • thermal insulation of an average degree - 1-1.9;
  • low thermal insulation - 2-2.9;
  • lack of thermal insulation - 3-4.

Double brickwork, small windows with three-chamber double-glazed windows, an insulated roofing system, a powerful foundation, thermal insulation using materials with low thermal conductivity - all this indicates the minimum coefficient of heat loss in your home.

With double brickwork, but the usual roof and windows with double frames, the coefficient increases to average values. The same parameters, but a single brickwork and a simple roof are a sign of low thermal insulation. Lack of thermal insulation is typical for country houses.

Home insulation
It is worth taking care of saving thermal energy already at the stage of building a house by performing the insulation of walls, roofs and foundations and installing multi-chamber windows

Choosing the coefficient value that is most appropriate for the thermal insulation of your home, we substitute it in the formula for calculating the heat load. Next, according to the formula, we calculate gas consumption to maintain a comfortable microclimate in a country house.

Gas consumption for specific examples

To determine what the natural gas consumption will be when heating a one-story house of 100m2, first you need to determine the heat load.

Heat load calculation

To obtain the most accurate data on the heated volume of the house, the volume of each room and auxiliary rooms where it is necessary to maintain heat is separately calculated. Length and width measurements are carried out along the skirting boards using conventional or laser tape measure.

We will do it easier: take the ceiling height for 2.5 meters, multiply it by the indicated area and get the house volume V = 250 m3.

Area measurement
If the room has a complex architectural form, a breakdown into rectangles, triangles, circles is performed, the area of ​​each of them is calculated and summed

To determine ΔT, column 6 is used in table 3.1 of SP 131.13330.2012. Indicated here is the air temperature of the coldest period, calculated on the basis of monthly average temperatures.

We find the name of the settlement where the heated object is located. Suppose this is Bryansk, therefore, the desired value is -12 ° C. The temperature in the living rooms according to GOST R 51617-2000 should be in the range of 18-24 ° C. We take the average value of 22 ° C, we obtain ΔT = 34 ° C.

We determine the degree of thermal insulation of the house and apply the corresponding coefficient. In the context of rising prices for coolants, most homeowners seek to improve the energy efficiency of heating by improving the thermal insulation of their homes, so it’s quite reasonable to use the first indicator of the average degree of thermal insulation, which is 1.

We bring all the values ​​according to the formula:

250 m3 × 34 ° C × 1/860 = 9.88 kW / h.

We apply the rounding rule to the nearest integer and get Q = 10 kW / h.

Boiler setting
Do not neglect automatic control - set different heating modes for night and day time to provide a comfortable microclimate regardless of the temperature outside the window and at the same time save up to 30% of gas

Recall that we only did heat engineering calculation at home, and now in line is the calculation of gas consumption. But for now it will be appropriate to make a small digression and clarify that the heating load can be calculated in a simplified way.

notice, that gas boiler power can be calculated for a particular object, taking into account all the technical nuances. According to the averaged data, 100 W / h of thermal energy falls on each meter of standard living space. Consequently, for a house of 100 m2 this indicator will be 100 W / h × 100 m2 = 10,000 W / h or 10 kW / h.

In this case, calculations by the formula and a simplified method gave the same result, but this is not always the case, and the difference often reaches 20% or more. Moreover, heat engineers recommend buying turbocharged and atmospheric boilers always with a margin of 20-25% with the expectation of the possibility of covering heat losses in days with critically low temperatures.

Trunk gas consumption

For the calculation, you need to know the efficiency of the gas boiler. You can see it in the technical specifications indicated in the accompanying documentation. We will choose a model that is suitable for the house of the specified area.

The main selection criterion will be the thermal power of the unit. Its value is very close to the value of the heat load and can be calculated by the same formula, but the temperature of the coldest five-day period is taken into account or an increasing coefficient of 1.3 is applied, because the boiler must have enough power to maintain heat in the house even in the most severe frosts.

Therefore, for heating 100 m2 You will need a boiler with a capacity of about 13 kW. Efficiency (n) of many models wall mounted gas boilers, for example, NEVA brand aggregates, is 92.5%. We will use this value in our calculations.

Convection boiler
Due to the design features of the combustion chamber, increasing the efficiency of heat exchangers, using the latent heat of water vapor, the efficiency of modern gas boilers exceeds 90%

The calorific value, or, alternatively, the specific heat of combustion (q) depends on the brand of gas used. What kind of gas is supplied to your home is best to check with the gas supply company.

By default, we substitute in the formula a rounded value corresponding to G20 gas with the lowest calorific value Hi, namely 9.5 kWh / m³. Pay attention to the units of measure - kilowatts are used, not megajoules.

All necessary values ​​are defined and it remains to reduce them to the formula:

V = 10 / (92.5 / 100 × 9.5). V = 1.1 m³ / h.

Thus, the consumption of main gas when heating a house of 100 m2 with a ceiling height of 2.5 meters is a little more than 1.1 cubic meters per hour. 24.2 cubic meters per day, respectively.

Now it’s easy to find out how much gas is needed for the entire heating season. According to state regulations, the average daily outdoor temperature does not exceed 8 ° C during the heating season. In the middle lane, this period lasts from October 15 to April 15 (183 days).

Since significant temperature fluctuations occur at this time, the daily gas flow rate is divided by 2 and then multiplied by 183. That is, about 2214.3 cubic meters of main gas will be required for the heating season.

How much propane-butane is needed for the heating season

Modern gas boilers are designed to use not only main, but also liquefied gas. To stock up with the necessary amount of fuel, not ordinary gas cylinders are used, but more capacious tanks - gas holders.

Use of gas holders
The use of gas tanks solves the problem of storing liquefied petroleum fuels sufficient to heat a house of 100 square meters.m, throughout the heating season in the temperate climate zone

When calculating the flow of liquefied gas required for heating a house of 100 m2, the same methodology is used, but the values ​​of some variables in the formula change.

For household needs, a liquefied propane-butane mixture is supplied.

Its calorific value is 12.8 kW / kg. Substitute this parameter in the formula and get:

V = 10 / (92.5 / 100 × 12.8). V = 0.8 kg / h.

When working on liquefied fuel, the efficiency of the equipment decreases, so the gas consumption increases by about 10% and amounts to 0.88 kg / h per day. The correction may be different for your boiler model. The specific value is indicated in the attached documentation.

Now we calculate the required amount of gas for the heating season: 0.88 × 24 × 183 = 3865 kg. This value also needs to be divided by 2, due to temperature fluctuations. Final result: for the heating season 1932.5 kg of propane-butane are required.

It will be useful to convert kilograms to liters. Based on reference data, 540 grams of liquefied propane-butane mixture corresponds to 1 liter. That is, for the entire period of the heating season, 3578 liters of liquefied gas will be required.

Conclusions and useful video on the topic

You are careful about thermal energy, but does your neighbor have less consumption anyway? The author of the video decided to share his own experience in using LPG for heating a house. Perhaps this information will be useful to you.

Can a temperature controller and a temperature sensor help to significantly reduce gas costs during the heating season? The video demonstrates how this happens in practice.

To determine the upcoming gas consumption for heating, higher education is not required. Knowing how the simplest mathematical operations are performed, you will calculate the necessary parameters with an acceptable error.

Along the way, you can identify weaknesses in your home, minimize heat loss, eliminate heat leakage to the outside and, as a result, take full advantage of blue fuel.

Please comment on the information we have provided with calculation balls and formulas for determining gas flow. You can share useful information on the topic of the article, ask a question or post a photo in the block below. It is possible that your recommendations will be useful to site visitors.

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