Under certain conditions, condensation occurs both inside and outside your home, but windows do not cause condensation. The source of condensation, or “sweating,” on windows and mirrors inside a home is humidity, or invisible water vapor, present in virtually all air. When this water vapor comes in contact with a surface, at a temperature below what is called the “dew point,” the vapor turns to visible droplets of liquid, or condenses, on the cooler surface. This often happens to bathroom mirrors and walls after someone has taken a hot shower. Condensation can also occur on windows during the winter if the inside humidity
level is high enough.
When it comes to condensation outside your home, it is simply a fact of nature. Exposed to certain conditions, like a clear night sky, still air or high relative humidity, the exterior surface of the glass can radiate heat away from your home and into the night air, allowing the glass temperature to fall below the dew point of the ambient air—creating condensation. Only when the glass temperature rises above the dew point will the condensation evaporate back into the air. Common examples of this are when dew forms on grass, car hoods and roofs and in common summertime conditions, with hot, humid air on the outside and colder,
conditioned air on the inside.
Condensation can form differently from window to window. Even windows that are located on the same wall of a home can experience different levels of condensation. This can happen due to varying humidity levels, elevation, landscaping near windows or different rates of exposure to the gradual warming effect of the sun.
Fore even more information on window condensation and ways to help reduce it, please download the below condensation brochure.