I own a window tinting shop and have been tinting for 30 years. There are a few things you need to consider here. Firstly, just because they sell a cling film or traditional adhesive-type film at a big box store or on Amazon or ebay or whatever, there are certain types of films that are need for certain applications. I have been working in client's houses before where they had gone to an auto parts store and bought limousine (5% visible light transmission) cling film and had that slapped up on some windows that faced south in their master bedroom. Double pane windows. Doing this is very likely to cause the seals to fail or the glass to crack, as this type of film absorbs too much heat. This product was designed to be used in cars, on tempered glass that doesn't care about heat. So, what you need is a reflective film, no darker than about 20% visible light transmission if you are going to be applying it to a doble pane window. I have never seen a cling film like this, but that doesn't mean they don't exist. I work with professional materials.
As far as applying a cling film, I have done this for a few of my clients and have never had it peel off (the film was clear and had decorative details that made it look like beveled glass, so no issues with heat buildup), and it's still in place 8 or more years later. The trick is to thoroughly clean the glass surface you will be applying it to, then use soapy water sprayed on the window to get the film in place. Squeegee most of the window, then trim the film to fit and squeegee the rest of the water out of the film.
Generally speaking, with a reflective film, the darker the film the more reflective it is from outside the house, therefore it is blocking more heat. Look for a film that blocks UV. A good film will block 98-100%. Don't go cheap, either - there are plenty of sketchy films out there I wouldn't touch with a ten foot pole.
Also, consider the fact that while you can get some benefit from a very light film, the darker you go (within the limits of the windows) the more benefit you get, because heat inside the house is not just coming through the glass from the outside, it also comes from inside the house from whatever is getting blasted by the sun that gets hot and starts radiating heat as well.
As far as applying a cling film, I have done this for a few of my clients and have never had it peel off (the film was clear and had decorative details that made it look like beveled glass, so no issues with heat buildup), and it's still in place 8 or more years later. The trick is to thoroughly clean the glass surface you will be applying it to, then use soapy water sprayed on the window to get the film in place. Squeegee most of the window, then trim the film to fit and squeegee the rest of the water out of the film.
Generally speaking, with a reflective film, the darker the film the more reflective it is from outside the house, therefore it is blocking more heat. Look for a film that blocks UV. A good film will block 98-100%. Don't go cheap, either - there are plenty of sketchy films out there I wouldn't touch with a ten foot pole.
Also, consider the fact that while you can get some benefit from a very light film, the darker you go (within the limits of the windows) the more benefit you get, because heat inside the house is not just coming through the glass from the outside, it also comes from inside the house from whatever is getting blasted by the sun that gets hot and starts radiating heat as well.
Be careful if you have double pane windows. I had to replace mine after the heat built up and they cracked.
It didn't for me, I still hear the voices.Tinfoil works best, just saying
We bought GILA cling film to mainly keep out glare . It has helped a lot been 8 yrs.
I just took this picture at 7pm, and the house is still getting a lot of sun.
Thanks for the very well written information that I will pass on to some of my neighbors and friends. We in our area of Idaho have some hot sun with some temps at 105-106 during the Summer and I have seen some in our area use the automotive type film you speak of. We have double pane glass windows that are rated Low E UV and they do a good job of keeping the house cool/warm all year.
If the issue is the west side of the house have solar made screens made for those windows and swap them back out for the other 7 months.
Glad to help! As a rule of thumb, you can use non-reflective ("black") types of tinting on single-pane tempered glass window around the home, such as storm doors and windows in a newer garage door, etc. Any tempered piece of glass will be marked as such with an etching in one of the corners of the window. For everything else, to be safe, it needs to be reflective. Also, reflective films give you amazing privacy during the day because they look mirrored from the outside, but at night when you have lights on in the home people will still be able to see in (like a limo at night with the lights on inside - you can see them but they probably can't see you) so additional window treatments are still needed for privacy unless you don't have neighbors to worry about.
