Awning windows are single sash models that tilt outwards and up when they open. Awning windows were first designed by Emilie Poisson and are primarily distinguished by the method in which the windows open. Because the windows have a hinge at the top, they pivot and open outwards at an angle. The windows resemble an awning over a roof, hence their name. Awning windows are hung horizontally like most common residential windows. They can be used by themselves or in conjunction with other models. Because they open outwards, awning windows are regularly installed in areas where air circulation is essential and are often found over kitchen sinks and countertops. Awning windows were once commonly used in schools and factories before the advent of air conditioning because they improved air circulation. Today, awning windows are made of a variety of materials and are usually opened with a crank or pull chains.