FRP (Fiber-Reinforced Plastic) windows are made by using glass fibers and resin-based materials that are formed through pultrusion; no steel reinforcement is required. They can be designed as sliding windows, windows that open inward, push-open windows, and lift-and-slide doors. These represent a high-performance new type of window and door system suitable for buildings with ultra-low energy consumption, passive houses, areas with extreme cold conditions, and high-rise buildings.