Proper window sealing minimizes energy losses

Accord­ing to the Fed­er­al Envir­on­ment Agency, heat­ing accounts for more than two thirds of final energy con­sump­tion in private house­holds. New thermal insu­la­tion can sig­ni­fic­antly reduce energy losses. Three quar­ters of the exist­ing build­ing stock are more than 30 years old, no longer energy-effi­­cient and in need of refur­bish­ment. Heat is lost above all through leaky win­dows and roofs as well as unin­su­lated front doors. This not only boosts heat­ing costs, but also sig­ni­fic­antly increases the risk of mold.

Tip 1: Find leaky windows with candle and paper

The inside must be tight­er than the out­side. Oth­er­wise, the warm and humid room air will con­dense on the colder sur­faces. The res­ult­ing mois­ture will cause mold growth. Espe­cially the insu­la­tion of older win­dows should be replaced after some time. The sea­son­al fluc­tu­ations in tem­per­at­ure can cause cracks in the insu­la­tion mater­i­als. If mois­ture pen­et­rates, they become por­ous. There are two easy leak tests. With a candle, you can determ­ine wheth­er drafts enter the room. And: If you can pull out a piece of paper jammed between win­dow frame and win­dow without any res­ist­ance, the con­tact pres­sure is too low.

Tip 2: Prevent damage by proper sealing

In order to pre­vent dam­age, it is cru­cial that seal­ing tapes and oth­er insu­la­tion mater­i­als are expertly and securely fastened to ensure their func­tion­al­ity. The inner, room-facing insu­la­tion lay­er must be vapor dif­fu­sion tight, the middle lay­er between frame and house wall must be filled with heat-insu­lat­ing mater­i­als. The out­er insu­la­tion lay­er should be open to vapor dif­fu­sion and able to res­ist all kinds of weath­er such as driv­ing rain. With floor-to-ceil­ing win­dows it is neces­sary to also seal the win­dow bot­tom on the room-facing side.