Well, whether it was UV or IR, it still made most of the film turn clear.
The space blanket material is also really thin, so it tears super-easy.
Here's a photo of the skylight - you can see how part is still silver, and part is clear (where you can see through to the sky and the tree).
The shreds hanging down are from me trying to gentry remove it.
Here's the photo of when I first put it up, just so you can compare the two.
I also put a small piece of the same material on a regular window downstairs. It doesn't seem to be showing any of the same degrading effects. That's a south-facing window, but I don't think it gets as much direct sunlight as the skylight does. I also wonder if the vertical window vs the 10/12 pitch of the skylight makes a difference?