Most window film will cut out over 98% of UV light which is partly to blame for fading (around 40%). other causes are visible light, another 25%, heat another 25% and miscellaneous causes around 10%. So the best thing for fabrics is to keep them dark and cool.
I have window tinting and I would never draw the curtains during the day, I love a sunny room. I try to keep my very meager stash in a wardrobe to keep in in the dark as much as possible
