Adding new windows without removing the old
I have a new construction home with Silverline windows with a U value of 0.49 (no loE, no Argon).
I noticed that I have 3 to 5 inches of sill space around the entire inside perimeter of the windows.
My thought is why not leave the new Silverline windows in place and simply add new replacement windows in the sill space.
This set up should give me a better U-value than any top of the line window used alone.
I would basically have 2 windows back to back with 1 to 2 inches of space between them.
I see no downside since I would only be tossing the existing windows anyway...why not keep them in?
I am considering American craftsman 9500-impact windows (the 9500 series was recomended by consumer reports.)
I appreciate any feedback.