The U value is the measurement of the rate of heat loss through the glazing. The lower the U value, the less heat will be needlessly escaping.

By changing one of the glasses in the standard glazing, it is possible to make the glazing more sound-proof, safe and private. Laminated glass makes the window more sound-proof. When a toughened glass breaks, the created pieces are small and have round edges that do not injure people; therefore it is advised to use it in crowded places and in big window panes.

Privacy is added by using tinted, opaque or patterned glasses. It is a very common solution for sauna and bathroom windows.