Windows come in a variety of different frame and glazing types. By choosing an energy efficient frame and a glazing type tailored to your climate, you can save significantly on your heating and cooling costs.
Types of Window Frames:
Aluminum or metal frames are very strong and light, however they conduct heat very rapidly. This makes the metal a very poor insulating material resulting in low energy efficiency for you home.
Composite frames consist of composite wood products, such as particleboard and laminated strand lumber. These composites have the same or better structural and thermal properties as wood, but resist moisture and decay better.
Vinyl frames are made of polyvinyl chloride (PVC) with UV stabilizers to keep sunlight from breaking down the material. Vinyl window frames do not require painting and have good moisture resistance. Vinyl frames have hollow cavities that can be filled with insulation making them thermally superior to wood frames.
Wood frames insulate fairly well, but they also expand and contract due to weather conditions. Wood frames also require regular maintenance.
Types of Window Glazing or Glass:
Gas fills improve the thermal performance of windows with insulated glazing. The space between the panes is filled with inert gas, usually argon or krypton, that has a higher resistance to heat flow than air.
Heat-absorbing tints is a window glazing that changes the color of the glass. These tints absorb a large amount of the incoming solar radiation through the window reducing the solar heat gain coefficient, visible transmittance, and glare. Tint, however, does not lower the U-factor because heat still passes through the windows because of conduction and re-radiation.
Insulated window glazing refers to windows with two or more panes of glass. The glass panes are spaced apart and sealed leaving an insulating air space. Insulated window glazing lowers the U-factor and the solar heat gain coefficient.
Low emissivity coatings (low-e) on glass control heat transfer through windows with insulated glazing. There is additional cost for low-e coatings, but can typically reduce energy loss by 30%-50%. The low-e coating is a very thin, virtually invisible metallic oxide layer deposited directly on the surface of one or more of the panes of glass. This coating lowers the U-factor, and different low-e coatings have been designed to allow for high, moderate, or low solar gain. Low-e coatings can also reduce a windows VT.