Consultation and assistance Calculate energy costs quickly

According to the Institute for Economic Oil heating (IWO), old windows are the weakest link in the house. Depending on their structural condition, they can account for loss of between 10 and 40 litres of heating oil per square metre of window area every year. For an average window area of 30 m2 in a single-family home this amounts to between 300 and 1,200 litres of heating oil. Save yourself this waste. By installing new windows, you can minimise the energy loss through your windows. Replace your windows now and save twice as much!

Energy costs CALCULATE

, € / Ltr. Heizöl
, ct / kwh
Key figures

K-value and/or U-value listed according to construction types, modification of K-value requirements for windows according to WSVO and EnEV

1976      Energy Conservation Act

1977      Thermal Insulation Ordinance I K 3.5 W/m²k for windows

1984     Thermal Insulation Ordinance II K 3.1 W/m²k for windows

1995     Thermal Insulation Ordinance III K 1.8 W/m²k for windows (equ. K-value 0.5, offset of solar heat gains)

2002     Energy Conservation Ordinance K 1.3 W/m² for windows (no threshold, usual calculated value instead)

Sources: K-Werte, Sanco das Glasbuch, Wärmeschutzverordnungen 1977 / 1984 / 1995 and EnEV 2002.

We are not responsible for ensuring that the old windows exhibit the specified heat transmittance coefficients (K- or U-values). Furthermore, we cannot guarantee that the stated savings possibilities will actually be achieved.