There are 4 main types of uPVC glass windows: Eco-friendly windows keep indoor spaces cool in summer and warm in winter while allowing natural light. Noise cancelling windows reduce outside noise by up to 75% through multi-chambered frames and sealed joints. Security friendly windows are constructed with laminated glass and multiple locking points to prevent break-ins. Safety glass windows are designed to shatter into small pieces instead of shards to eliminate risk of injury if broken.