U-value (thermal insulation)
Measures heat loss through the door in W/m²K. The lower the number, the better the insulation.
Definition
The U-value quantifies the amount of heat passing through 1 m² of wall for a 1 K (1 °C) temperature difference between inside and outside. It is expressed in W/m²K. An uninsulated steel up-and-over door is around 6.5 W/m²K, an LPU 42 sectional door (42 mm) 1.3 W/m²K as installed, and the LPU 67 Thermo 1.0 W/m²K (0.91 W/m²K with the optional ThermoFrame).
Typical values in Luxembourg
- Uninsulated steel up-and-over door (Berry): 6.5 W/m²K installed.
- LPU 42 sectional door (42 mm): 1.3 W/m²K installed (1.2 W/m²K with ThermoFrame).
- LPU 67 Thermo: 1.0 W/m²K installed, 0.91 W/m²K with the optional ThermoFrame.
- For a heated garage integrated into the home, choose a door with the lowest possible U-value; your energy adviser will check the requirements that apply to your project.
Energy-bill impact
- Switching from a U = 3 door to a U = 1 door significantly reduces heat loss through the opening.
- Savings are more significant when the garage adjoins a living space than a detached garage.
- ThermoFrame improves the overall opening U-value by eliminating the frame thermal bridge.
Frequently asked questions
Why is the LPU 67 U-value better than a 42 mm door?
Panel thickness (67 mm vs 42 mm) and the density of the injected polyurethane foam directly affect insulation. Thicker panels and lower-conductivity foam give a lower U-value.
Do I need the best U-value for an unheated garage?
No, a U-value of 1.30 W/m²K (standard LPU 42) is plenty for an unheated garage. The LPU 67 Thermo premium only pays off for a garage integrated into the heated envelope.