I went to a home on Saturday where they were suffering from too much heat. Upon inspection, the glass turned out to be double glazed units, around 15 years old, imported from Canada. This made me look a lot closer and one unit in particular showed signs of seal failure.
Seal failure is when air leaks into the space between the two panes of glass. This one unit did not have the silver spacers with the little air holes, but just black silicon seals. Normally, the holes hide a desiccant which absorbs moisture and the reason behind this is to absorb any moisture that is either present at the time of manufacture or leaks over time in a substandard unit. Once the desiccant is saturated, your glass starts to develop moisture and eventually condensation.
The glazing industry tends to invalidate any claim where window film has been installed. In the USA, window film manufacturers offer to  take over the Insulated Glass Unit (IGU) warranties to reassure the customers that tinting the glass will not become a risk to their units.
Normally, a well constructed IGU with a well chosen film will not fail within the warranty period. What the film can do, is accentuate an existing flaw and speed up the rate of failure. In effect, it will highlight a defect in the IGU. It's not the film causing t he problem.
Anyway, in this case, the failure was obvious, before any window film was installed. I advised the owners to have the glass changed, before any tinting was getting done.
With an increasing sophistication in glass, it is vital to deal with someone who is well versed in this topic to avoid nasty surprises down the track.

We use a lot frosted film and have done so for many years. In the early days, a key factor was the pricing. So we went with a product easy to use and cost effective.
After a couple of years, we started getting phone calls with complaints of the frosting shrinking from the edges. Not the sort of calls we wanted.
What went wrong?

There are 2 types of frosted vinyl on the market, Calendered and Cast, and here are the differences:
Calendered vinyl can be compared to a piece of pastry getting rolled out. It wants to shrink back to its original shape.
Cast vinyl is like chocolate, once melted, you spread it out and it sets. No memory and no shrinkage.
The picture above shows how much the film has shrunk away from the edges. If you like this look, great! For your enjoyment, the clear border is now nice and sticky and can act as a fly trap. Sometimes you even get some irregular wrinkles in the film and of course, it shrinks unevenly too!

Consequently, we have stopped using pastry and use chocolate instead. So, you can buy frosted film from hardware shops or the internet and find that you have bought pastry. Or you may pay a little more and enjoy the chocolate from us. And here is another bonus: Our chocolate does not make you fat!

If you are looking around for the best deal, ask them, if it's calendered or cast vinyl. And don't be surprised, if they don't know what you're talking about.......

Everybody in New Zealand is aware of the damage UV does, not just to people (Melanoma), but also to furniture and furnishings. Consequently, people ask for a UV film to prevent fading. There are a number of products on the market that block UV and not all of them are window film.
Here are some "facts" and "myths" about fading:
Myth: If you block UV, things will not fade any more.
Fact: No product will stop fading. UV blockers (present is window film and other applications) will reduce fading to some degree.
Myth: Only UV is responsible for fading.
Fact: UV is only one component of fading. Other major contributing factors are heat and light. Some fading is caused by other environmental factors, but generally only a small contribution.
Myth: Fade reduction can be given as a percentage.
Fact: Every material or colour is affected in different ways, so a fade reduction of 85% may be possible in one particular fabric, of a specific colour. A different material or colour will give a different result. For example, dark leather and fabrics discolour more than light colours. The question is: A given percentage of fade reduction is based on what?

We feel, a rating system of stars, or "good, better, best" is more appropriate than giving products a specific %. Having said this, any product on the market only blocking UV can be rated "good" only, no more. In order to get "better", or "best" results, the heat and light issues must be addressed. Even then, fading will still occur, but at a much slower rate.

Did a job today in a "Granny Flat" using SV30. (picture not of the flat, but SV30). The brief was to reduce the heat and reduce glare. This is a common request, because as we age, we become more sensitive to light in particular.
The customer was initially worried that the unit would become too dark, but once the first set of windows was complete, she was delighted with the result. The bonus with this film is the increase in privacy. Just about impossible to see in now.
SV30 is fairly reflective, but not a mirror.