Consumption-Based Heat Load Calculator
Calculate the heat load of your building quickly and easily from your actual energy consumption (gas, oil, pellets, etc.).
Calculating Heat Load from Consumption
What is this calculation for?
The consumption-based heat load calculation provides a quick initial estimate of the required heating capacity. It is particularly useful for:
- Heat pump sizing: Initial guidance on what capacity class is needed
- Renovation planning: Assessment of the current energy condition
- Heating system replacement: Reference value for the new heating system
Pitfalls to consider
The calculation is based on past consumption and has some limitations:
- User behavior: Those who heat sparingly or leave rooms unheated get values that are too low
- Hot water share: The proportion for hot water preparation must be estimated
- Heating period: Incomplete years or unusual winters distort the result
- Building changes: After renovations, old consumption data is no longer meaningful
Rough estimate vs. detailed calculation
| Consumption-based (this calculator) | Standard calculation per DIN EN 12831 | |
|---|---|---|
| Accuracy | ± 20-30% | ± 5-10% |
| Effort | 2 minutes | Several hours |
| Data required | Only consumption + location | Building geometry, U-values, ventilation |
| Suitable for | Initial orientation | Binding planning, funding applications |
Recommendation: Use this calculator for an initial estimate. For final heating system sizing, we recommend the detailed heat load calculation.
How the Calculation Works
The consumption-based heat load calculator determines the heat load from your actual energy consumption. It uses:
Energy Consumption
Your annual consumption is converted to kWh and adjusted for hot water share:
- Gas: Consumption in m³ × calorific value (10.0 kWh/m³ for natural gas H)
- Oil: Consumption in liters × calorific value (9.8 kWh/L)
- Pellets: Consumption in kg × calorific value (4.9 kWh/kg)
Climate Data (PVGIS TMY)
Based on your location, hourly climate data from the PVGIS Typical Meteorological Year (TMY) is used:
- 8,760 hourly values per year
- Calculation of degree hours (sum of temperature differences)
- Determination of full load hours
Calculation Formula
Heat Load [kW] = Heating Energy Demand [kWh] / Full Load Hours [h]The full load hours are derived from the degree hours divided by the temperature difference to the design outdoor temperature.
Typical Results
| Building Type | Specific Heat Load |
|---|---|
| Passive house/New building | below 50 W/m² |
| Renovated old building | 50-100 W/m² |
| Unrenovated old building | 100-150 W/m² |
| Needs renovation | above 150 W/m² |
Example: A house with 150 m² and 2,000 m³ gas consumption typically has a heat load of 12-15 kW (80-100 W/m²).
Further Information
Embed This Calculator on Your Website
Would you like to embed this consumption heat load calculator on your own website? Simply add the following code to your HTML:
<!-- Consumption Heat Load Calculator by PV-Calor -->
<ge-mini-verbrauchsheizlast lang="en"></ge-mini-verbrauchsheizlast>
<script src="https://www.pv-calor.com/user/plugins/gecomponents/assets/ge-mini-verbrauchsheizlast.embed.js"></script>Available languages: Change lang="en" to one of: de, en, fr, it, es, pt, nl, da, sv, pl, ru
Embedding is free. Contact us if you have any questions.