Single hung windows open and close by moving the lower panel or sash of the window. Thus, only half of the windows area can be opened for ventilation. This is the most traditional-looking style of window.
Double hung windows are virtually the same as single hung windows except that both the upper and lower sashes can be moved. The advantage is that you can adjust the sashes so that warmer air escapes at the top of the window opening while cooler air enters from the bottom.
Horizontal roller windows are like a single or double hung window turned on its side. One or both of the sashes move sideways on rollers to open the window. Horizontal roller windows can be an economical choice for larger openings.
Casement windows open and close using a crank or lever. The casement style opens up the entire window are to the breeze, and seals very tightly against drafts and moisture. Casement windows also provide easy egress in case of emergency.
Fixed lite windows do not open at all, but are designed to provide light and architectural interest where ventilation is not needed. They range from the familiar picture window style to squares, circles, octagons and a variety of other shapes, in virtually any size.
Sliding glass doors come in two, three or four panel versions. They provide a contemporary look and are popular for providing access to pools, patios and decks. Pay particular attention to the rollers and how easily the doors slide.
French doors offer a more traditional, elegant look. Fixed panels can be used in combination with operable doors.