Choose windows with low air infiltration rates

Leaky windows waste energy.
Windows with significant air leaks compromise the building envelopeExterior components of a house that provide protection from colder (and warmer) outdoor temperatures and precipitation; includes the house foundation, framed exterior walls, roof or ceiling, and insulation, and air sealing materials., lowering indoor comfort and increasing heating and cooling costs. Look for windows with a leakage rate no greater than 0.03 cubic feet per minute per square foot. Properly sealed windows also reduce outside noises. Generally, double-hung and horizontal sliding windows have more air leaks than casement windows where the sash closes tightly against a gasket. Air leakage around the window frame can be greater than the sash leakage if the window is not installed properly.

Green points

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).

Learn more in the Green Building Encyclopedia

Windows, Glass, Ratings and Installation

Further resources

Efficient Windows Collaborative
National Fenestration Rating Council