|Replacement Sash Windows, Moving Pane Windows|
|Window built with moveable panels, called "sashes" which form a frame that holds a glass pane|
A sash window is a window frame which holds panes of glass. These panes move within the frame, vertically, horizontally, inwards or outwards. Replacement sash windows generally refer to casement windows (including awning and hopper windows), horizontal sliding windows or vertical sliding windows. Replacement sash windows may be installed as single units, be placed side-by-side next to other sash window units or be installed as part of a group of windows that includes different types of windows. Sash windows provide a maximum face opening which allows for ventilation of anywhere from one-half of the total window area to the entire window area. Depending on the window's operation, sash windows may include springs, counterweights and weather-stripping to hold them in place.
Homeowners turn to replacement sash windows when they are considering their options for new windows during a remodeling project for a number of reasons. Sash windows provide efficient venting of a room. In the case of double hung vertical sash windows they can draw in cool air from the bottom opening while allowing warm air at the top of the room to escape. There are also a variety of possibilities to move the sashes within the frame which give the homeowner the opportunity to clean both the inside and outside panes of each side of the window.
There are a number of options for a replacement sash window. Three of the most popular are casement swing-in and swing-out windows, vertical sliding windows (double hung and single hung) and horizontal sliding windows.
 Casement Windows
Casement windows are single pane windows which are hinged on one side of the sash and open as either swing-in or swing-out operation by means of a crank or push mechanism. They are available in many sizes and provide maximum ventilation. Casements may require extra care because of the mechanical crank and weight which press on the lower hinge. Screens install either on the inside or the outside of the window, depending on which direction the window opens. Casement windows are available in vinyl, aluminum, fiberglass, wood, wood clad and composite frames. Homeowners may order casement windows with multi-panes for optimal insulation and a Low-E (low-emissivity) coating on the window to block a portion of the sun's radiative rays. Casement windows come in a wide range of sizes and shapes.
Casement windows may be used as emergency exit windows if their size meets the local code.
 Awning Windows
Awning windows are a type of casement windows which are hinged on the top of the sash, instead of the side. They may open inward or outward and are often installed in bathrooms, basement bedrooms and on top of other windows to increase ventilation.
 Hopper Windows
Hopper windows are a type of casement windows which are hinged on the bottom of the sash. They open both inward and outward and are frequently installed under a larger window as a compliment to the window design.
 Vertical Sliding Windows
Vertical sliding windows consist of two panes which can be raised or lowered to provide a ventilation opening. The internal mechanism of the vertical sliding window permits easy manipulation of the panes. Vertical sliding windows are often installed in bedrooms, kitchens, living rooms, dining rooms, home offices and in lofts and attics. They are manufactured from a variety of framing materials including wood, wood clad, vinyl, composite, aluminum and fiberglass. Glazing options for vertical sliding windows include multi-pane windows and Low-E (low emissivity) coating which reduced solar gain. Screens clip into the outside of vertical sliding window frame and can be easily removed for cleaning. Vertical sliding windows are elongated windows which are installed in long window openings.
There are two main types of replacement vertical sliding windows, single hung windows and double hung windows.
 Single Hung Windows
Single hung windows have two sashes but only the lower sash may be raised or lowered. The top pane is fixed. Single hung windows are sometimes chosen as a less expensive vertical replacement sliding window alternative.
 Double Hung Windows
Replacement double hung windows feature two sashes, both of which can be raised or lowered. These windows are easier to clean than the single hung windows.
 Horizontal Sliding Windows
Horizontal sliding windows often simply referred to as 'Sliding Windows', have two sashes. In some horizontal sliding windows, one of the sashes is fixed while the second moves within the frame. In other horizontal replacement windows, both sashes can move horizontally within the frame. Horizontal sliding windows are one of the least expensive operable window options available on the market today. They are produced with fiberglass, composite, wood, wood clad, aluminum and vinyl frames and may include single, double or triple glazing. It is possible to order horizontal sliding windows with a Low-E coating to lower energy loss.