You're about to switch to electric heating, but how many watts do you actually need per cubic meter? A miscalculation means either shivering on the sofa or paying unnecessarily high electricity bills. And believe me, nobody wants the latter.
With the transition to gas-free housing – a goal the Netherlands aims to achieve completely by 2050 – it is essential to know precisely what power your electric heating system needs to provide.
In this article, I explain it to you step by step:
- The exact formula for calculating the power required per m³
- The difference between electric radiators and infrared panels
- How to take into account high ceilings and insulation
- Practical examples for your specific situation
Understanding the problem
Many people choose their electric heating at random. Yet, every room is different.
- Basing calculations solely on square meters instead of cubic meters
- Disregard the insulation
- Not understanding the difference between convection and infrared
For a well-insulated house, approximately 30 to 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 pitched 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
- They heat the air
- Ideal for continuous heating
- Power = Volume × insulation factor
Infrared panels
- They heat people and objects
- 20–30% more efficient
- Power = (Volume × factor) × 0.7
Step 4: Final calculation
Formula:
Power = Volume × W/m³ × correction factors
- Many windows: +10%
- Corner house: +15%
- Detached house: +20%
Example :
50 × 35 × 1.15 = 2012 W
Step 5: Distribute the power
- Large rooms: 2 to 3 sources
- Place near exterior walls
Common mistakes
Mistake 1: Basing calculations solely on square meters
Mistake 2: Ignoring heat loss
Mistake 3: Undersizing to save money
Practical examples
Modern living room:
91 m³ × 35 W = 3185 W
Attic room:
39.2 × 45 × 1.15 = 2028 W
Checklist
- Measure length, width, height
- Determine the insulation
- Choosing the type of heating
- Calculate and round up
Conclusion
With careful planning, you can avoid high bills and discomfort. The right power output makes all the difference.