Window Film Heat Reduction

can solar protection films work together on double-glazed windows?
Is it a good idea to apply solar protection films onto double-glazed windows to further reduce the heat transmittance from the sun?
will it be a good idea? anybody knows about the possible reduction in heat transfer and probably the pros and cons?
a good website with information would be very helpful.. =D
Adding the Window Film will definitely reduce the heat transfer depending on what type of window film you select and how well it is installed. I have used it many times in my practise with great success. I suggest you google 3M window film dealers within you geographic area to get the information you need to make a informed choice.
www.http://spacelifts.ca