One of the most popular styles of uPVC Windows, casement windows, with their unobstructed opening, offer an attractive view to the outside world. uPVC Casement Windows are suitable for any style or height of the building. The windows come with a sash that is connected to the outer frame by means of friction hinges or butt hinges, perfect for maximum air circulation. Casement windows are very energy efficient and come in varied designs like side hung, and top hung.