According to calculations performed by the Institute for Warmth and Mobility, older windows are the weakest point in a house. Depending on their structural condition, these can lose between 10 and 40 liters of heating oil per square meter of window surface annually.
In a single family house with an average window surface of 30 m2, this would be between 300 and 1200 liters of heating oil. Don’t let this go to waste. Installing new windows will reduce energy losses through your windows to a minimum. Replace your windows now and save twice!