Windows leak air on windy days from day one, so we have to add a space heater in the living room. The former 50 year old single pane windows worked better. Today (Christmas morning) two years after installation, it's windy and rainy and there's water running in all the windows on the windward side of the house. Drywall and hardwood floors are going to be ruined. Previous calls asking for help were a joke. They added a piece of open cell foam about 1" x 2" to the joint between upper and lower sash. No help, plus they fell out within one week. What a joke these windows are, they lead between the sash and frame and between upper and lower sashes. The sashes by themselves are great, but the true measure is the whole window system including frame and interaction between the two. I plan to measure air leakage and sue the company.