PVC DWV pipes do not degrade much at all "when installed in a protective chase which is also within the insulated thermal envelope of the home" *AS REQUIRED*.
Yes, PVC will deteriorate with UV, and, yes, latex paint (not oil base) may be used to "protect it" from UV, but, it is still required to be in a chase (protection from damage) and within the thermal envelope of the house (protection from freezing).