WINDOW CONDENSATION The Learning Center One of the probable reasons for your replacing your old windows was because they were drafty, and when the wind wasn't blowing in, slight cracks in the windows allowed the excess humidity in your house to escape. Your new windows do not allow as much humidity to escape, therefore, it is showing itself on the glass. In other words, they are more airtight – less air is entering your home from the outside. The air leaking from older windows evaporated the moisture before it could collect. This is your first indication that you have too much humidity in your home. The condensation resistance factor (CRF) and "R" factor of your new windows will also play a part in the amount of condensation that appears.  The higher the CRF and "R” factor, the less condensation will appear relative to the humidity of your home.      4. Why is there condensation on my new windows? < back to list of questions about window condensation 3245 Miracle Drive Murrysville, PA 15668 724-387-2991 PA Contractor ID PA001856