In early times, windows were no more than holes cut in walls to let in air and light. The development of glass into frames was a significant improvement because light could still be transmitted, but weather effects (e.g. wind, rain & snow) could now be blocked. Lately, windows have become increasingly more sophisticated, using new materials with more energy-efficient properties.
Other Window Types
There are other glass window types each designed for a specific functional need. Fixed units usually contain a higher percentage of glass and have better (or lower) solar heat gain control, but they do not provide as much ventilation compared to operable windows.
Hinged Windows Examples include casings, awnings and hoppers. Air leakage is low when the hinge is clamped shut, creating an effective seal.
Sliding Windows Single-hung, double-hung or horizontal sliders generally allow more air to leak inside compared to hinged windows.Repeated openings and closings tend to
Sliding Glass Windows & French Door Windows Sliding glass windows are designed to act like a door, as well as a window. It’s difficult to weather strip the area around the sliding sill, thus creating more air leakage. In contrast, French door windows are more solid and provide better air blockage.
The type of material used to construct a frame is very important. It’s used to measure the size, weight and durability of a window, and it helps to determine a window’s overall thermal performance.
Aluminum Frames Aluminum frames are widely used in residential window units. It’s easy to work with because the material is light, durable and low maintenance. Aluminum is not subject to corrosion and is a perfect material for sliding glass doors because of its strength and lightness. The one drawback of aluminum is that it's highly conductive and, thus, increases the U-value of a window unit. In cold climates, condensation problems can occur as frost or moisture builds up on the inside of the frame. To combat the heat loss and condensation problems, aluminum frame manufacturers have developed better technologies utilizing “thermal breaks.”
Wood Frames Long ago, wood frames were used because the material was easily available. Now, with the emergence of new cost-effective frame technologies, wood frames are considered a high-end window frame purchase. Wood is very durable and lasts longer than other frame materials. Wood frames have a natural aesthetic appeal and they blend in well with traditional home designs. However, wood frames are high maintenance products. They need special treatments to reduce warping and prevent decay. As for thermal protection, wood frames perform well. The thicker the wood frame, the more heat insulation it provides.
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