Insulation values Whirlpool Cover
A hot tub cover with 15 cm insulation offers significantly better heat retention than one with 10 cm. That's because the so-called U-value – the heat transfer value – is lower for thicker covers. So less heat escapes from your hot tub.
- A 10 cm thick cover is ideal for warmer climates and for hot tubs placed indoors.
- A 12 cm thick cover is suitable for year-round use, already offers good heat retention and contributes to energy efficiency.
- The 15 cm version is ideal for cold winters and especially high energy efficiency – recommended if your hot tub is located in very cold regions or you want to keep energy losses as low as possible.
Cover thickness |
Typical U-value (W/m²K) |
Area of use |
Insulation value / energy efficiency |
10 cm |
0,34–0,38 |
Standard, mild winters |
Good (basic insulation) |
12 cm |
0,28–0,32 |
Colder regions, efficiency |
Very good (less heat loss) |
15 cm |
0,24–0,27 |
Extremely cold, economy mode |
Excellent (maximum) |
What exactly is the U-value?
The U-value (heat transfer coefficient) describes how much heat passes through one square metre of a component at a temperature difference of 1 Kelvin between the warm and cold sides. The lower the U-value, the better the insulation.
In short:
- It measures heat loss in watts per square metre and Kelvin, i.e. W/(m²K).
- It always refers to the entire component (e.g. the hot tub cover), not just the insulation material.
- Low U-value = little heat loss = good insulation and lower heating costs.
- High U-value = lots of heat loss = poor insulation.
