DIY Window Film: When It's OK and When to Hire a Pro

https://smart-wiki.win/index.php/Daylight_and_Privacy:_A_Guide_to_Daylight_Redirecting_Films

Glass is a patient material. It holds heat, refracts light, and carries the fingerprints of daily life. Window film is a simple, sometimes transformative way to tune how a window behaves without replacing glass or altering the structure of a room