Gas Consumption Calculator

Gas consumption calculator 2026 online. Convert kWh and m3 for house and apartment

This documentation describes the Livewire add-on, which calculates the annual energy demand and the corresponding gas volume based on the heated area, building quality, DHW share, system efficiency and gas calorific value. Here you will find full calculation logic, step-by-step instructions, examples, a quality mapping table, FAQs, implementation notes, a JSON pattern for feeding live parameters, as well as a checklist for the user and developer.

What the calculator does and who will use it

The calculator converts the building's energy into gas consumption in a clear way. The user enters the heated area in square meters and selects the building quality profile, which we map to the annual energy factor in kWh per m2. We add the percentage of domestic hot water, correct the total for the installation efficiency and convert the fuel energy into cubic meters through the HHV calorific value. The tool works quickly, does not require expert knowledge and is useful in budget planning, analyzing the impact of insulation, comparing modernization options and in conversations with the contractor. The solution will benefit home owners, community managers, technical advisors and anyone who wants to avoid costly surprises during the heating season.

Input fields and default ranges

All fields are numbers and can be updated dynamically. Selecting custom activates a custom factor that replaces the poor, avg, good, or vgood profile. This allows the calculator to scale from a quick estimate to a scenario with audit data.

Algorithm - full calculation course

// 1) Selection of the building quality factor
coef = quality == 'custom' ? max(1, custom_coef) : mapQualityToCoef(quality)

// 2) Energy for heating central heating
space_kwh_year = area * coef

// 3) Total energy after adding DHW
dhw = dhw_share / 100
total_kwh_year = space_kwh_year * (1 + dhw)

// 4) Fuel energy after correction for efficiency
eta = eff / 100
fuel_kwh_year = total_kwh_year / eta

// 5) Gas in m3 at the given HHV
m3_year = fuel_kwh_year / hhv
m3_month = m3_year / 12

// 6) Series for the monthly chart
series_m3 = [m3_month, ..., m3_month] // 12 items

The calculator does not break down the months seasonally. The series is equal to the average of annual consumption. In practice, consumption will be higher in winter. To add seasonality, extend the series with monthly weights based on degree days or historical invoices.

Mapping quality - kWh factor per m2 year

The factor only covers space heating. We add DHW separately. This division improves readability and facilitates recalculation after changes in household habits.

Step-by-step instructions for use

1. Enter the heated area in square meters. Do not include a garage without heaters or an unheated basement.
2. Select the building quality profile closest to reality. If you have an audit, use custom mode and enter the value from the report.
3. Determine the share of DHW in the total energy. For a family of four, start with 20 percent.
4. Provide the efficiency of the heating system. It is worth adopting a conservative value so as not to underestimate the result.
5. Check the HHV calorific value on the latest invoice. If you don't have data, use 10.5 as a starting point.
6. Click Recalculate. Read kWh per year, m3 per year and m3 per month. The chart will show an equal yearly division into months.

Examples of full calculations

House 120 m2 - AVG quality, DHW 15 percent, efficiency 90, HHV 10.5

Energy for central heating: 120 × 120 is 14,400 kWh. After adding 15 percent hot water, the total energy is 16,560 kWh. After taking into account the efficiency of 90 percent, the fuel energy is 18,400 kWh. Division by HHV 10.5 gives approximately 1,752 m3 of gas per year, or 146 m3 per month averaged. This result is used for budget planning and for comparison of scenarios after thermal modernization.

Apartment 65 m2 - good quality, domestic hot water 22 percent, efficiency 92, HHV 11.0

CO: 65 × 80 gives 5200 kWh. The total energy after adding hot water is 6344 kWh. An efficiency of 92 percent increases the fuel output to 6,896 kWh. With HHV 11.0, the annual consumption is 627 m3. Monthly approximately 52 m3. Comparing the avg to good profile, you can see the real impact of better insulation on the result.

Energy-efficient house 150 m2 - vgood quality, DHW 25 percent, efficiency 96, HHV 10.0

CO is 7500 kWh. With DHW 25 percent: 9375 kWh. An efficiency of 96 percent produces 9,766 kWh of fuel. HHV 10.0 translates into 977 m3 per year and approximately 81 m3 per month. The result shows how low thermal transmittance translates into gas bills.

Assumptions and limitations of the model

• The model is static. It does not take into account the outside temperature in a given year or heat gains from the sun or devices.
• We treat DHW as a percentage of total energy. In practice, you can take consumption per person and convert it to energy - this calculator takes the route of simplicity.
• Efficiency includes heat source, transmission and regulation. Better regulation will reduce fuel energy without changing the usable energy.
• HHV may vary seasonally and regionally. It is worth updating the value along with the invoice.

JSON to feed live parameters

{
  "custom_coef": 110,
  "dhw_share": 18,
  "eff": 91,
  "hhv": 10.8
}

In the response, simply return the selected keys. Each of them, if any, will be overwritten in the component. A download error does not block local calculation.

Scenario comparisons - how to interpret

Reducing the quality factor from 120 to 80 kWh per m2 per year in a 120 m2 house gives 4,800 kWh less usable energy per year. After correcting for 90 percent efficiency, you reduce fuel consumption by approximately 5,333 kWh. At HHV 10.5 this is almost 508 m3 less gas per year. Even with constant distribution fee rates, the difference in fuel has a noticeable effect on the budget. Therefore, the calculator is well suited to justifying investments in insulation, replacing windows and modernizing the node.

Frequently asked questions

Can I enter the total area

No. We count actually heated meters. Garages, attics and unheated basements should not enter the field area.

Where to get HHV

From the last invoice or operator's website. If you don't have the data, enter 10.5 and update after verification.

Why are my bills different than the result

The model does not take into account seasonality, heat gains, mechanical ventilation and weather changes. It is used for scenario comparisons, not for accounting settlements.

Can I add seasonality

Yes. Just replace the equal series with a vector of monthly weights. You can calculate weights from historical accounts or public degree-day data.

Implementation and UX

• The view uses a grid and tabs with clear field labels. The Download button completes the parameters from JSON.
• A bar chart has a Y-axis of zero and equal labels M1 through M12. This emphasizes the average nature of the series.
• It is worth adding an aria label with units - m2, kWh per m3, percentage - for easier accessibility.
• In case of a download error, show short information and leave current field values ​​without reset.

Testing and validation

User errors and how to avoid them

• Entering total meters instead of heated meters. Measure the real heating zone.
• Confusing HHV with the price of gas. Here, HHV is kWh per m3, not dollars.
• Assumption of unrealistically high efficiency. Leave a margin of safety.
• DHW not taken into account for a large family. Set the dhw_share field higher and recalculate.

Summary

Gas consumption calculator 2025 allows you to quickly estimate useful energy, fuel and m3 volume. You can easily compare the impact of building quality, hot water, efficiency and HHV. The tool supports user education and facilitates communication about costs. By adding live data and seasonality, you can expand it with further functions, but already in the basic version you get a reliable starting point for technical and budget decisions.

Calculate your consumption forecast