U-Wert-Berechnung von Fenstern

Außenmaß Rahmen

m   x   m


U-Wert: W/m²K Eingabehilfe

g-Wert: Eingabehilfe

ψ-Wert: W/mK    Eingabehilfe


Breite: mm     U-Wert: W/m²K

Breite: mm     U-Wert: W/m²K

Breite: mm     U-Wert: W/m²K


Achtung Beta-Version. Probleme und Fehler bitte umgehend melden.


1000 1000


Fenster:   1,00 m²
Rahmen:   0,419 m²
Verglasung:   0,581 m²
Länge Randverbund:   3,05 m
Rahmenanteil:   41,9 %
U-value:Uw = 1,46 W/(m²K)


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Quick Start Guide

This U-value calculator analyzes your component (for example, wall, roof, ceiling, etc.) with regard to insulation, moisture protection and heat protection:

  1. Choose a material from the left panel and place it on the drawing surface.
  2. Lay all layers together
  3. Lastly insert wooden beams into the insulation layer.
Examples: Wall   Roof   Ceiling

The main results are displayed at the bottom of the screen. More detailed information can be found on the left-hand side of the screen using the buttons U-value, humidity, heat, etc.

For commercial usage, calculations are made according to DIN EN ISO 6946 (U value), DIN 4108-3 (moisture protection) and DIN 68800-2 (drying reserve).

Notes on Planning

Moist and moldy walls are the nightmare of many builders. Therefore, the U-value calculator examines your insulation for potential moisture problems. The article Wasserdampfdiffusion und feuchte Wände (in German) explains how moisture and mold can occur. At this point, the following simplification is sufficient:

In winter the warm room air contains more moisture than the cold outside air. This is why water vapor diffuses through the component from the inside to the outside. Because the outer, colder layers can only contain very little water vapor, it must be ensured that the water vapor escapes as easily as possible from the outside. If the water vapor accumulates on a cold layer, condensation is likely to occur.

Moisture protection in wood structures is particularly important. For this reason, in addition to moisture protection according to DIN 4108-3 (in German), a drying reserve in accordance with DIN 68800-2 (in German) is required, which should also allow harmless drying of unintentionally penetrated moisture.

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