One of the biggest signs your window insulation isn’t working anymore is when certain rooms feel colder even though the heating is on. In Everett, WA, the damp weather makes it more noticeable if seals have failed or frames are letting air in. I was reading about DIY vs professional window replacement Everett and it explains why improper installation can also affect insulation over time. Sometimes it’s not just the glass, but how everything was fitted in the first place.