Window Replacment

I have single pane windows in my 05 Carriage 5er. I was thinking of replacing them with double pane. It looks pretty easy to do. I can't find out what make they are. I would appreciate it if anyone knows what brand Carriage used. If amyone has done this to there rig how hard was it and do you think the cost and time was worth it. We fulltime and are often in extreme hot and cold weather.

Thanks