U-Factor

Definition: A measure of heat transfer through a material or assembly, typically used for windows and doors. Lower U-factors indicate better insulating properties.

Relevance to energy: U-factor directly impacts the energy efficiency of buildings by affecting heat loss through windows and doors, influencing heating and cooling requirements.

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Benefits:

• Helps compare thermal performance of windows and doors
• Lower U-factors lead to better energy efficiency
• Can contribute to lower heating and cooling costs

Drawbacks:

• Windows with lower U-factors are often more expensive
• Doesn't account for solar heat gain
• May vary depending on the specific part of the window or door

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Statistics: According to the U.S. Department of Energy, windows with low U-factors can reduce heating costs by up to 34% in cold climates compared to single-pane windows.