Which type of window cannot be opened?

The type of window that cannot be opened is the fixed window. Fixed windows are designed to remain in a stationary position and serve primarily as a source of natural light and a view, rather than ventilation. They are typically sealed into the frame and do not include any moving parts that would allow for opening. This makes them ideal for locations where airflow is not a concern or where the aesthetic view is more important than functionality.

In contrast, sliding, casement, and awning windows include mechanisms that allow them to be opened and closed. Sliding windows feature panels that glide to one side, while casement windows have hinges that allow them to swing open outward. Awning windows are hinged at the top and open outward, allowing for ventilation while keeping rain out. Each of these designs incorporates functionality to facilitate airflow, making them operational compared to the fixed window's permanent closure.