Window Types

Window Operating Types

When selecting windows for your home, it's also important to consider how they're operated.

Some operating types have lower air leakage rates than others, which will improve your home's energy efficiency.

Air leakage is the rate of air infiltration around a window, door, or skylight in the presence of a specific pressure difference across it.

It's expressed in units of cubic feet per minute per square foot of frame area (cfm/ft2). A product with a low air leakage rating is tighter than one with a high air leakage rating.

There are numerous window operating types to consider. Traditional types include the following: 

·  Awning

Hinged at the top and open outward. Because the sash closes by pressing against the frame, they generally have lower air leakage rates than sliding windows.

·  Casement

Hinged at the sides. Like awning windows, they generally have lower air leakage rates than sliding windows because the sash closes by pressing against the frame.

·  Fixed

Fixed panes that don't open. They're airtight but not suitable in places where window ventilation is desired.

 ·  Hopper

Hinged at the bottom and open inward. Like both awning and casement, they generally have lower air leakage rates because the sash closes by pressing against the frame.

·  Single- and double-hung

Both sashes slide vertically in a double-hung window. Only the bottom sash slides upward in a single-hung window. These sliding windows generally have higher air leakage rates than projecting or hinged windows.

·  Single- and double-sliding

Both sashes slide horizontally in a double-sliding window. Only one sash slides in a single-sliding window. Like single- and double-hung windows, they generally have higher air leakage rates than projecting or hinged windows.

Be sure to read my page on Which Window is Best.

Carl

Source: U.S. Department of Energy - Energy Efficiency and Renewable Energy
A Consumer's Guide to Energy Efficiency and Renewable Energy