Which terms do I need to know before I start shopping for windows? Text

As you shop for new windows, you’ll hear and read a lot of jargon about glazing, spacers and cladding. Here is a glossary of terms that might help you understand what is being discussed.

Cladding. This is the vinyl or metal material that covers the outside of the wood frame.  They’re designed to be easy to maintain and never require painting, although some manufacturers make paintable versions. Rosie recommends that Arizona residents avoid vinyl because they can deteriorate faster than metal under the hot desert sun.

  • Clad windows have wood frames on the interior side and either vinyl or aluminum cladding over the wood on the exterior. You can paint the inside any color you like, but you never have to paint the outside. Rosie’s ideal window: aluminum-clad wood.

Glazing. This isn’t the glaze or paint that you put on the window; it’s the number of panes of glass the window has. You have three choices:

  • Single-glazed. This is one pane of glass, and it’s the most energy-inefficient choice. Especially in a severe hot or cold climate, a single pane of glass will do little to keep the weather outside and the air-conditioned or heated air inside.
  • Double-glazed. The smartest buy for Arizona homeowners, double-glazed windows have two panes of glass with a small air space in between. The air acts as an insulator to keep hot outdoor air from getting indoors and cool air-conditioned air from escaping to the outdoors. Some window manufacturers fill that air space with Argon gas, which serves as an even more efficient insulator.
  • Triple-glazed. These super-efficient windows have three panes of glass (or two glass panes and a plastic one inside) with two air spaces in between. They’re great at keeping the noise out, but they’re expensive. In fact, the payback in energy savings can take more than 10 years.  


Double-hung, single-hung. These windows have top and bottom sections or “sashes.”

  • Double-hung windows allow you to slide both the bottom sash and the top sash up and down.
  • Single-windows have only one movable sash, so just the bottom part slides up and down, and you can’t move the top sash.  


Casement window/awning window. These are window styles.

  • A casement window’s hinges are on the side, so the window swings outward instead of up and down. A casement window usually has a crank that the user rotates to open and close it.
  • An awning window is hinged at the top, so it swings out at the bottom to open. It’s typically operated by a crank as well.

Thickness of air space. The energy efficiency of double-glazed windows, two glass panes with an air space in between depends, in part, on how thick that air space is. A very thin air space doesn’t insulate as well as a thick one. Rosie recommends that you buy windows with an air space of at least 5/8 of an inch for maximum energy efficiency. But bigger isn’t necessarily better when it comes to air space. Beyond an inch, the air space does not make the window more efficient.

Argon gas. Most window manufacturers will be able to substitute inert Argon gas for the air in the space between the panes in double-glazed windows. The gas acts as another layer of insulation and can reduce heat loss through the window.

Low-e coatings. Low-emissivity coatings are thin, transparent coatings of silver or tin oxide that allow visible light to pass through a window as they reflect radiant heat. New “southern low-e” coatings are a good fit for Arizona homes because they reflect the heat away from the house.

Tinted glass. Tinted glass and tinted window films can help prevent heat from wafting through your windows when it’s hot outside. But unless you’d like to have colored windows, there’s no need to pay extra for tinting. Today’s low-e window coatings do a better job of preventing heat gain.

Edge spacers. The edge spacer holds the panes of window glass apart and adds an airtight seal to an insulated glass window. Aluminum is the traditional material for edge spacers, but cutting-edge spacers are made from thin-walled steel and have a thermal break. Others are made of silicone or butyl rubber.

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