Unplasticised polyvinyl chloride is made with a number of stabilising chemicals that protect the surface of your door from harm and prevent the colour from bleaching out. You'll still need to occasionally clean it, much like you would clean your uPVC windows, since grime may damage uPVC over time. This goes for your windows as well. We suggest using a special uPVC cleaning solution which also creates a dirt-repellent protective film.