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Casement, Awning and Hopper Windows

Casement, hopper and awning windows represent three variations of the same frame design – a design based on hinges.

Casement windows have a hinge at the side; awning windows have their hinges located at the top, while hopper windows are an inverted version of awning windows: they have their hinges located at the bottom.

These models are also based on compression seals (crank outs) and provide higher airtight and energy-efficiency than that provided by gliding and double-hung windows.

Casement windows advantages

Casement window Casement windows have a hinge at the side and crank out to open. They are one of the most common and time-tested designs, and admit several customizations. They are particularly energy-efficient - perhaps the most efficient window after fixed-pane windows.

Due to the window sash pressing against the frame on closing, they are particularly high-performing in terms of air-leakage.

Disadvantages of casement windows

If you intend to use storm windows, or screens, casement windows aren’t a good option. They are also relatively obstructive (comparatively to fixed pane or gliding windows) in some locations, and can be more difficulty to clean on the outside.

Due to its design, there are also some limitations in terms of the size of individual casement windows. They can't be too large.

Ventilation

Casement windows open outward fully (or inward, in some models), providing great natural ventilation.

Awning windows

Awning windows are hinged at the top and swing outward instead of being hinged at the side as the casement windows.

They share the advantages and disadvantages of casement windows: they are energy-efficient and a good option for controlled natural ventilation; they can be located in a many places, and arranged next to other windows: they are commonly used above large patio doors for natural lighting and ventilation.

Limitations

Awning windows do not combine well wind exterior storm windows and their opening and closing can be slightly more difficult then gliding windows, for instance.

Eventual window screens should be placed on the inside.

Ventilation and lighting

Awning windows allow full and controlled ventilation (the window can be entirely opened, or just partially).

Hopper windows

A hopper window is an inverted awning window, opening inwards… with the sash hinged at the bottom.

Hopper windows are very used in basements, but not only. They are popular, and comparatively to awning and casement windows have the same advantages (high energy efficiency, good ventilation) and disadvantages (they are less easy to open and close, and to clean, and can be obstructive in some low places).