Benefits of uPVC Double Glazed Windows and Doors. Our uPVC Windows and doors are specifically engineered to withstand Australia’s harsh, unpredictable climate. Compared with standard residential Aluminium frames, our windows and doors are up to 5 times more energy efficient and are designed to reduce your power bills by up to 90%! You’ll keep your house at the perfect temperature all year round, no matter which season it is outside. Unlike Timber and Aluminium, our products won’t crack, fade, peel, , rot, corrode or warp over time. All of our products are extremely durable and built to last for a lifetime.