Exterior condensation happens when the Dew Point Temp is higher than the surfaces that have condensation. At night, as outside temperatures drop, so do surface temperatures on items such as exterior window glass, siding, grass, and cars.
In the morning when the air temperature starts to rise and the humidity levels increase, the Dew Point temperature rises faster than the surfaces still cool from the night before. When this happens condensation will form on these cooler surfaces.
When the outside temperature warms these surfaces, the moisture will dissipate away. The window is working as designed and acting like an exterior wall, keeping the moisture outside and warm air inside.
Why didn't this happen with my old windows?
- Older less energy-efficient windows allowed warmth from inside the home to reach the outside glass pane, keeping it warmer than the Dew Point temperature, so moisture could not form.
- Newer, more energy-efficient windows will not allow as much warmth from the inside to reach the outside glass pane, therefore the outside pane remains cooler than the Dew Point temperature, allowing condensation to form.
