The features below can change a window or door’s performance in a big way. These product features have an even bigger impact in the Northern climate zone where more stringent U-Factor requirements are making it more challenging to meet ENERGY STAR criteria with dual-pane glass. Here’s what you should keep in mind:
Window type: Casement, awning, and picture windows are typically more energy efficient than double-hung and single-hung windows. Casement and awning windows seal tighter when the wind blows against them, and picture windows are fixed (inoperable) so they’re the most efficient of all window types.
Glass construction: Dual-pane glass has two panes of glass with an argon-gas blend in between for added insulation. Triple-pane glass features one additional pane of glass and one additional argon-gas blend filled air space. The latter also offers three opportunities to include a Low-E coating, versus only two on dual-pane glass.
Glass coatings: The right combination of glass coatings can help a product reflect energy in a way that makes the window more efficient. The right coating or combination of coatings will depend on climate zone, but keep in mind the benefits of PassiveSun glass with HeatLock technology in the Northern zone (insulation plus higher solar gain) and SmartSun glass with HeatLock technology (insulation while reducing solar gain) in the other climate zones.
Grilles: The presence of grilles and even the size of the grilles matters. This is because they can help conduct energy between the panes of glass and take away from the air space, thereby decreasing energy efficiency. Energy spacers are available with A-Series windows and doors and don’t touch the glass, so they can help achieve an authentic look while reducing energy transfer. The most energy-efficient choice is to skip grilles.
Breather tubes: These tubes help keep windows and doors from becoming pressurized at high elevations. They allow air to escape from the air pocket in between window panes and are required above 4,000 feet of elevation. They also decrease the energy performance (i.e., increase the U-Factor) of a window or door.
As you can see, there are many factors that affect a window or door’s energy performance. Being aware of these factors can help you decide when to pull different levers to improve performance.
