Though this old and anecdotal comparison is true, it is entirely a result of where those uPVC materials from: Europe. Europe has much less UV than NZ and therefore doesn’t need to have the same levels of protection against UV that NZ does. The main reason for the differing levels of UV is because of how far each region is away from the equator. Regions that are closer to the equator have more direct sunlight and UV light than areas that are further from the equator. England starts at 50° away from the equator. NZ goes from 35-45° from the equator.