While the frame of your windows forms the basis for much of the window’s properties, for many it is the glass that really makes the difference. It is, after all, the part of the window that most affects what we can most readily see and feel from the window. While the frame and the glass work together to determine a window’s performance, the glass gets a lot of attention from the way it affects the light and air entering our homes.

Right glass for windows

Insulated glass is the term used for windows with multiple panes of glass; two is usual, but three is an option for colder climates. The insulating part comes from the way the air in between the panes helps to reduce the amount of heat transfer through the window glass – in this, old, single-pane window glass just can’t compare. Insulated glass also serves to reduce the amount of outside noise entering your home, a side effect of its ability to block the transfer of heat.

The ability of the glass to reduce heat transfer in general can be enhanced by adding an inert gas fill. This is done by replacing the “normal” air between the panes with an inert gas, either argon or krypton. The inert gas fill is clear and does not obstruct vision, but can dramatically increase the ability of the window to block the transfer of heat.

There are several tints and coatings that can be applied to the glass directly. Heat-absorbing tints change the color of the glass so it blocks more heat, and the darker glass serves to reduce glare. Reflective coatings reflect more light than heat, though they reduce the glare from within the home. Low-emissivity glass, with a microscopically-thin layer of metal oxide, is for many the best glass option, and provides a dramatic increase in energy efficiency, reducing heat loss by anywhere from 30% to 50%.

The only thing left to consider is the style of the window, which we’ll see more of in part III.