You are about to switch to electric heating, but how many watts do you actually need per m³? A miscalculation means either shivering on the sofa or paying unnecessarily too much for electricity. And believe me, nobody wants the latter scenario.
With the transition towards a gas-free home – a goal the Netherlands wants to achieve completely by 2050 – it is essential to know precisely what output your electric heating system needs to deliver.
In this article we explain step by step:
- The exact formula for calculating the required output per m³
- The difference between electric radiators and infrared panels
- How to account for high ceilings and insulation
- Practical examples for your specific situation
Understanding the problem
Many people choose their electric heating randomly. Yet every room is different.
- Relying solely on m² instead of m³
- Not taking insulation into account
- Not understanding the difference between convection and infrared
For a well-insulated home, approximately 30–40 W/m³ is required.
Step-by-step instructions
Step 1: calculate the volume
Formula:
Length × Width × Height = Volume (m³)
Example:
5 × 4 × 2.5 = 50 m³
For a sloped roof, use the average height.
Step 2: insulation quality
- Well insulated: 30–40 W/m³
- Average insulation: 40–50 W/m³
- Poorly insulated: 50–70 W/m³
Step 3: type of heating
Electric radiators
- Heat the air
- Ideal for continuous heating
- Output = Volume × insulation factor
Infrared panels
- Heat people and objects
- 20–30% more efficient
- Output = (Volume × factor) × 0.7
Step 4: final calculation
Formula:
Output = Volume × W/m³ × correction factors
- Many windows: +10%
- Corner house: +15%
- Detached house: +20%
Example:
50 × 35 × 1.15 = 2,012 W
Step 5: distribute the output
- Large rooms: 2–3 sources
- Position near exterior walls
Common mistakes
Mistake 1: relying solely on m²
Mistake 2: ignoring heat loss
Mistake 3: undersizing to save money
Practical examples
Modern living room:
91 m³ × 35 W = 3,185 W
Attic bedroom:
39.2 × 45 × 1.15 = 2,028 W
Checklist
- Measure length, width, height
- Determine insulation level
- Choose the type of heating
- Calculate and round up
Conclusion
With a proper calculation, you avoid high bills and lack of comfort. The right output makes all the difference.