Things do fade over time if exposed to UV rays. Take a piece of construction paper and place it in front of the window. Come back in a few weeks and take a look at it. Guaranteed the front won’t match the back.

UV not only fades colors, it damages/deteriorates fabrics and most plastics. UV protection not only make your items look better, it makes them last much longer. Also, it’s better for the items if you can minimize changes in temperature and humidity, too – you especially don’t want condensation forming on anything.