I have had an issue with my Pella window fogging up in my house for over 15 years especially when the temperature turn cold. I have had Pella out to inspect at $75 a visit to just tell me it's humidity. I don't understand why my Andersen windows that are 20 yrs old in the house don't have the same issue. Pella also tries to tell me it's the side of the house the windows are located, well it happens on the left side and the back of my house. It's frustrating since the windows were expensive and they don't stand behind their product, the only solution they offer is sending me cleaning instructions. I ask why bow Pella window is exempt from the fog issue since the humidity in my house is the issue.