Taking Away The Pane…
While all the parts of a window system contribute to its U-factor, the window’s frame is a major factor in a window’s aesthetics; the look of the window frame can enhance or detract from the overall look of your home. A discussion of how the different components of a window contribute to its energy profile would be incomplete without a discussion of the different materials used in a window frame, and how that affects the window’s energy efficiency.
Aluminum or metal frames are light, durable, and typically require little or no maintenance. They also conduct heat very rapidly, increasing the window’s overall U-factor. This can be addressed via a thermal break, a strip of insulating plastic placed between the sash, the part of the window that frames the glass pane, and the rest of the frame itself.
Frames made of wood provide good insulation, i.e., a low U-factor, but can expand or contract due to extremes in weather. Wooden frames need to be regularly maintained, though the frequency of maintenance can be reduced by adding aluminum or vinyl cladding, i.e., sheeting formed to fit over the wood to provide a weather-proof layer that prevents water from penetrating into the wood.
Frames made of vinyl are constructed from polyvinyl chloride, or PVC, with stabilizers to prevent the material from deteriorating due to exposure to sunlight. Vinyl has good resistance to moisture and does not require painting. The frame’s U-factor can be decreased by filling hollow cavities in the vinyl frame with insulating material, giving it better energy efficiency than frames made of wood or uninsulated vinyl.
Similarly, frames constructed of fiberglass have cavities that can be filled with insulation, resulting in a frame that has better energy efficiency than wood or uninsulated vinyl.
Composite frames are made from wood products, such as particle board and laminated strand lumber, and have the same or better structural and energy properties as wood in addition to having better resistance to moisture and decay.
…And Ending It All
It can be difficult to juggle the numbers against the aesthetics of window design and material; the particular look and feel you want might not be the most energy-efficient option for you. Modern technology is improving all the time, however. Consulting with a contractor can lead to confusion as you are faced with the many options available to you. The information here is intended to reduce that confusion and help you make an informed decision.
