I have completed about 1/2 of the window film treatment and have already noticed a difference. I measured the window temperature on the inside bottom (the coldest part of the window since cold air falls) of both a north window with the film and without the firm. Both windows do not have any forced air heat on them and the window with the film on it is at this moment 57 F the other window sill 54 F. So there seems to be a small 2 degree difference but 2 is better than 0!
This film is suppose to bounce back 55% of the heat from the house in the winter and reflect out 72% of the heat in the summer. I am putting this on the north and west ends of the house only as I want to collect as much winter sun as I can during the winter months. Also on the south side when I put the screens back on in the summer I will keep out over 80% of the sun from coming in the house. The trouble with putting this film on the south side is that in the winter months it will block way to much sun! And energy from the sun is FREE and delivered to your home free of charge so why stop it form coming into your home? We seem to build a window and then not let the natural daylight come in to help heat your home.
And you have to remember that the summer sun goes very high in the sky and with such a high angle not as much sun goes through the south windows. I may consider putting a small shading device alone the top of the south windows (PV modules?) to shade them and using that energy to perhaps operate a solar evaporative cooler if need be.
The only film I plan to install on the south side is UV film that will block out 99% of the harmful UV rays that fade your furniture. Other than that the south side does not get the Titanium film. Oh and by the way the other film I am putting on also blocks about 99% of the UV to boot!
Well off to get some more window film!