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Exceed code requirements on window U-values

Tags: Add a floor above, Kitchen or bath addition, New construction, Gable or eave end add-on, Gut rehab, Home performance & weatherization, Gut rehab, Home performance and weatherization, windows, cold, dry, General Information, Windows and Doors, hot_humid, marine, mixed_humid, Windows

High performance windows are a good investment.
Energy codes set minimum U-values for windows by climate zone, but exceeding these standards means more energy savings. U-values are the inverse of R-values used to rate insulation, so lower U-values mean higher insulating values for windows.
Typically, windows with the lowest U-values have double glass with one low-eLow-emissivity coating. Very thin metallic coating on glass or plastic window glazing that permits most of the sun’s short-wave (light) radiation to enter, while blocking up to 90% of the long-wave (heat) radiation. Low-e coatings boost a window’s R-value and reduce its U-factor. surface, argonInert (chemically stable) gas, which, because of its low thermal conductivity, is often used as gas fill between the panes of energy-efficient windows. gas, low-conductivity glass spacers and frames. They may also be triple glazed. The National FenestrationTechnically, any transparent or translucent material plus any sash, frame, mullion, or divider attached to it, including windows, skylights, glass doors, and curtain walls. Rating Council maintains a list of certified windows at it web site (see Further Resources).

Minimum U-values by climate zone:

Zone 1: U-1.2
Zone 2: U-.75
Zone 3: U-.65
Zone 4 (except marine): U-.40
Zone 5-8 & Zone 4 marine: U-.35

Green points

LEED for HomesLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. : Up to 3 points for windows whose NFRC ratings substantially exceed Energy StarLabeling system sponsored by the Environmental Protection Agency and the US Department of Energy for labeling the most energy-efficient products on the market; applies to a wide range of products, from computers and office equipment to refrigerators and air conditioners. requirements (EA 4).
NGBSNational Green Building Standard Based on the NAHB Model Green Home Building Guidelines and passed through ANSI. This standard can be applied to both new homes, remodeling projects, and additions. /ICC-700: Meeting Energy Star requirements is mandatory; up to 12 points for windows with enhanced performance (703.3.1).