It is always good to see that other blogs, especially one as highly regarded as Treehugger, agree with your assessments. In a previous article titled, New AC Unit vs Window Tint, we determined that window tint is much more affordable an better ROI (return on investment) than both a replacement AC or replacement windows.
At more than $5k for a new central AC unit or over $250 per replacement window, window film easily becomes the most economical choice at $2.25 per square feet for professional DIY window film.
… a complete myth that replacement windows will save you money. In fact, they go so far as to say that the payback period for replacement windows is probably twice as long as the life of the window.
The preservation society offers more tips: