Number of glass pane layers

Single-pane windows are inefficient compared with newer double- and even triple-paned windows. Between the panes are inert gases that helps insulate the window. The more panes, the more protection from the cold, with the interior glass staying the warmest.

Insulation of window frame

The window frame conducts heat that contributes to a window's overall energy efficiency, particularly its u-factor. That measures the amount of heat loss a window permits. The lower the u-factor, the greater a window’s resistance to heat flow and the better its insulating properties.

Reflective glass coating material

Low-E coatings keep out the summer heat and act like sunscreen for your house. They reflect heat and protect your valuables from harmful, fading ultraviolet light without noticeably reducing visible light. The special coating can reduce fading by up to 75%.