What about windows on the south side of buildings? Does direct sunlight damage the product?

Almost all of our films have a UV coating built into the layers, so they will be protected from the sun damage somewhat (prolonged life over non-UV films at least) also, just so you know, this particular product is designed for "walls/paint" not glass. We do have dry erase products for glass as well. https://www.decorativefilm.com/product-search?Search=dry+erase