Old Age: Windows age. Its seals may eventually degrade after exposure to wild weather for several years, coupled with consistent usage. They break down or fail and permanently fog in between the panes of windows.
High Humidity: Fogging windows are also common during summer because of high moisture content levels in the air. Cooking, bathing, and drying clothes indoor expose the air to be warm and wet. Warm wet air can condense on the cooler glass surfaces.
Ventilation: The weak airflow can also trap water as well as air inside your home. Though enhancing the seals between doors and windows enhances energy efficiency, diminished natural air flow can make them vulnerable to condensation issues.