What is window condensation?
It is a common misconception that windows cause condensation. However, nothing could be further from the truth! Windows do not cause condensation, they simply provide a visual indication that the relative humidity inside a structure is higher than it should be for the conditions. The conditions effecting condensation are exterior temperature, interior temperature, and relative humidity. A well insulated structure with very little vapor release (ventilation) does not allow moisture to escape to the outside, so the relative humidity continues to rise with normal use such as dishwashing, bathing and simply breathing. As the relative humidity climbs, the vapor pressure increases and moisture tries harder to migrate to the outside. Finally, the relative humidity reaches dewpoint and begins to condensate on the coldest surface that it can reach. in many cases, that surface is a window. Consider the typical 1950’s residential construction. Homes were, in general, poorly insulated and loosely
